CA1039068A - Column stabilized semisubmersible pipelaying barge - Google Patents

Abstract

Abstract of the Disclosure The pipelaying barge comprises a pair of laterally spaced, elongated hulls having a plurality of upstanding columns spaced therealong supporting a working platform in spaced relation above the hulls and on which platform is carried a pipe section assembly line and one or more cranes movable longitudinally along the platform and capable of servicing the pipe section assembly line and performing lifting operations off at least one barge beam and both barge ends, depending upon the longitudinal location of the crane.
The hulls buoyantly support the vessel, including its platform, in low draft floating condition with the hulls having freeboard for efficient transit and other purposes. The hulls have ballast compartments to submerge the hulls and portions of the stabilizing columns to a high draft condition with the mean waterline at a necessary and desirable locus intermediate the height of the stabilizing columns, whereby the pipelayer is maintained in a semisubmerged high draft floating condition with the platform elevated above the waterline accordingly.
A transition segment is connected to the stern of the barge for support of the "air length" segment of the pipeline between the stern of the barge and the point of entry of the pipeline into the water and preferably also supporting a short segment of pipeline in the water as the pipeline is payed out from the barge. To lay pipe, the pipelayer barge is disposed in the high draft condition and ballasted to provide a preset angle of trim. Pipe sections are transferred to the pipe assembly line by the crane and/or longitudinal and transverse conveyors and the barge is advanced in a manner such that the assembled pipeline is payed out from the barge over the transition element for final disposition on the sea bottom. The stability and motion minimizing characteristics of the barge are such that the attitude of the barge in trim about the pitch axis when in high draft pipelaying condition is maintained within an angle not in excess of plus or minus one-half degree of the preset trim to avoid introducing undesir-able pipe stresses due to change in the attitude of the barge in trim about the pitch axis caused by longitudinal movement of one or more cranes; further, change in trim angle exceeding plus or minus one-half degree is offset by ballast correction correlated to longitudinal location and movement of the crane to maintain the barge trim within plus or minus one-half degree of the preset trim angle whereby pipelaying and crane operations can be performed simultaneously without interrup-tion.

Description

This invention relates to a pipelaying barge, and more particularly to a twin hull column stabilized semisub-mersible pipe laying barge carrying a pipe assemhly line and means for laying pipeline onto the sea bottom and to methods of operating such barge.
Increased offshore activities, such as attempts to drill and exploit gas and oil wells at sea, have created a demand for underwater pipelines for transporting gas and oil from offshore wells or production sites to near-shore or on-shore terminals for storage and/or ultimate delivery of

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the gas and/or oil to refineries and to the consumer. To date t large numbers of pipelines have been laid offshore along the sea bottom by conventional pipelaying barges to connect the production sites with the near-shore or on-shore facili-ties, Such conventional barges are usually characterized by ~-a single standard barge hull which is generally rectangular in shape (with a bow at the front) and operates in surface floating condition (not semi-submerged~ with a pipe section assembly line normally disposed along the hulls topside and along which pipe sections are welded one to the other; the pipeline is payed out from the stern of the barge which is not much above the water line and generally over a stinger which extends from the barge stern and supports the portion of the pipeline which initially enters the water, Pipelaying ~;
operations have heretofore generally been conducted in rela-tively calm or sheltered waters; where conducted in regions having medium to h~gh seas (waves in excess of 4 to 5 feet) ;, such operations are usually suspended until such sea3 subside and calm conditions arise. That is, conventional pipelaying operations are highly restricted by sea state condition sinc~
excessive motion in pitch~ heave and roll~ especially pitch, can excessively stress the pipe to cause rupture of the pipe and/or its concrete coating, Also, on-deck equipment of~en is damaged or lost due to wave action, Conventional pipelaying barges which are single hull surface floating vessels have stability characteristics which provide excessive motion in even moderate sea conditions

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whe~eby pipelaying operations are highly restricted by sea state conditions since excessive vessel motîon in heave, pitch and roll even in relatively moderate sea conditions can alter the curvature of the pipeline being laid to the extent of exceeding allowable stresses with resultant rupture of pipe or coating For example, surface floating pipelaying barges of this type can operate only in sea states having wave heights up to about 4 or 5 feet or in special cases six feet Wave aetion against such barges, when in sea states having wave heights in excess of these limits, normally causes excessive vessel motion which precludes pipelaying operations.
Such conventional single hull vessels have inherently low natural periods in roll, pitch and heave and inherently high GM. The low natural periods are apt to be close to the ~
period of the waves, thus causing motion amplification while a high GM results in high stability and consequent abrupt and large correcting motions when the barge is subjected to roll and pitch excitations. The above-discussed stability and motion characteristics of the described conventional pipelay-ing barges do not permit pipelaying operations to proceed in medium and high sea states.
Due particularly to the discovery and exploitation of oil and gas in the North Sea and other offshore areas which are consistently and continuously subject to relatively high wind and sea states, there has been and is a need for a vessel which can operate to continuously lay pipe in such waters notwithstanding such high sea states Pipelines have

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been and are continuing to be success~ully laid in one such ~-region, i.e, the North Sea, by two semisubm4rsible twin hull column stabilized derrick barges o~ the type disclosed in U.S.
Patents No, 3,835,800 and No. 3,685,305 and No. 3,704,596 (owned by the assignee of this application) such derrick barges having been modifiPd to carry pipe assembly lines and ancillary equipment for pipelaying operations and including deck-to-water pipe section transition stingers such as dis-closed in said U.S. Patents Nos. 3,685,305 and 3,704,596.
The present invention provides a novel improved semi-submersi~le twin hulled column stabilized pipelaying barge construction and system which not only provides advan-~ages over above-discussed conventional pipelaying barges (which are fundamentally different from the pipelaying vessel o this application), but also provides novel features and advantages for pipelaying which are not incorporated as such in the vessels disclosed in the three pat0nts identified in the immediately preceding paragraph.
Accordingly, it is a primary object of the present invention to provide novel and improved apparatus and methods of operation relating to a semisubmersible column stabilized pipelaying barge which would generally preclude pipelaying operations by conventional single hull barges and which also provides new advantageous features as compared to the afore-mentioned semisubmersible derrick barges of assignee's afore-mentioned patents when used as pipe layers.

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~39~6~3 It is another object of the present invention to provide a novel and improved column stabilîzed semisubmersible twin hull pipelaying barge having one or more cranes movable longitudinally along the barge platform for general lifting purposes including resupply of pipe sections to the barge and to the pipe assembly line from supply boats; and novel and improved methods for operating such barge in semi-submerged high draft condition.
It is still another object of the present invention to provide a novel and improved twin hull semisubmersible column stabilized pipelaying barge and method of operating such barge wherein the barge in high draft condition is bal- :
lasted in correlation to the location and/or movemen~ of the crane or cranes along the platform to maintain the attitude of the barge in trim within a predetermined angle of change from the operational trim angle set prior to change in location .~ . .
and/or movement of the crane or cranes along the barge and to maintain such angle within narrow limits to prevent ~xcess resultant stresses on the pipeline exceeding allowable stresses which would damage the pipeline and/or any coating applied to the pipeline, :~ It is a further object of the present invention to ...~
provide a novel and improved twin hull semisubmersible column stabilized pipelaying barge and method of operating such barge wherein the barge in high draft condition is ballasted in conjunction with and correlation to the location and/or .

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movement of the crane or cranes along the plat~orm to maintain the attitude of the barge in trim within plus or miDus one-half :
degree of a preset operational trim angle.
It is a still further object of the present invention ~ ~
to provide a novel and improved twin hull semisubmersible column stabilized pipelayer barge with means for establishing proper distance between the top of the hulls and the mean waterline at "load line draft" in the high draft condition of the barge for such pipelaying barges having a particular column height between the hulls and platform.
It i~ an even further object of the present invention to provide a novel and improved pipelaying combination including a twin hull semisubmersible column stabilized pipelayer barge and a pipeline transition segment wherein the pipeline transition segment is adjustable about a transversely extending axis in relation to the attitude of the barge about its trim axis and to the horizontal to control the curvature of the pipeline extending from the barge and over the pipeline traDsition segment so as not to exceed allowable stresses on the pipeline and its coating and also with such adjustment being made in conjunction with and correlation to operation of the ballast means for maintaining the draft of the barge in the desired high draft condition and also maintaining the barg~ trim angle less than plus or minus one-half degree variation from the preset angle of trim whereby the relative angular relation between the barge and pipeline transition - . . . . . . .
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segment is substantially maintained throughout pipelaying operations so as not to exceed allowable stresses on the pipeline and/or its coating.
In accordance with one broad aspect, the invention .
relates ~o a column stabilized semisubmersible pipelaying barge and pipeline transition combination comprising: a pair of elongated hulls disposed in spaced side-by-side relation; :
a working platform spaced above said hulls a predetermined .
height; means for supporting said platform in spaced relation ~:
above said hulls including columns connected to said hulls and said platform; the distance between the extremities of said :
barge along the longitudinal centerline of said barge being :
substantially greater than the distance between the extremities of said barge along the transverse centerline thereof; said hulls having ballast compartments for ballasting said barge ~to alter its draft between a low draft hull supported :
floating condition and a high draft semisubmerged column stabilized and pipelaying operating condition; said columns having predetermined cross-sectional areas and being located ~
on the hulls to provide righting moments about the pitch and :
roll axes of said barge when in said high draft semisubmerged :
condition; the area of said columns, the number thereof, and the distance of the columns from the longitudinal and transverse centerlines of the barge being such as to provide a greater righting moment about the transverse pitch axis than the righting moment about the longitudinal roll axis when the barge is in high draft semisubmerged pipelaying operating condition; means for supporting and paying out pipeline from one end of said barge including pipeline transition means for !~
supporting the pipeline extending from said barge end into the water; means including said pipeline transition means for . . ~
controlling the curvature of a segment of the pipeline extendinq .... , , ~ , .

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from said barge end and over said pipeline transition means;
crane means carried by said barge with means mounting said crane means for movement substantially longitudinally of the barge along said platform; said crane means including means .
for lifting, transferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said crane means along the barge platform a predetermined distance . ~.
when said barge is in said high draft semisubmerged pipelaying condition will cause change in the angle of trim of the barge exceeding about plus or ~inus one-half degree as compared to the barge angle of trim prior to such longitudinal movement of the crane means absent sufficient connter-correction of such change in barge trim angle caused by such movement of said crane means; ballast means for counteracting the change in angle of trim of the barge caused by movement of said crane -means longitudinally along said platform to maintain the angle of trim of said barge within an angle of change about the trim axis so that the curvature of the pipeline extending from said barge end and over said pipeline transition section does not exceed allowable stress for the pipeline and any coating on the pipeline.
In accordance with another aspect, the invention relates to a column-stabilized semi-submersible barge comprising: a pair of elongated hulls disposed in spaced side-by-side relation; a working platform spaced above said hulls a predetermined height; means for supporting said platform in spaced relation above said hulls including columns connected to said hulls and said platform; the distance between the extremities of said barge along the longitudinal ~enterline of said barge being at least 2.5 times greater than the distance between the extremities of said barge along the trans~erse centerline thereof; said hulls having ballast ~ -8A-. , . , : :

~03~ 8 compartments for ballasting said barge to alter its draft between a low-draft hull supported floating condition and a :~
high-draft semi~submerged column-stabilized operating condition; said columns having predetermined cross-sectional areas and being locatea on the hulls to provide righting :~
moments about the pitch and roll axes of said barge when in said high-draft semi-submerged condition; the area of said columns, the number thereof, and the distance of the columns from the longitudinal and transverse centerlines of the barge being such as to provide a greater righting moment about the :~
transverse pitch axis than the righting moment about the longitudinal roll axis when the barge is in high-draft semi-submerged operating condition; crane means carried by said :
barge with means mounting said crane means for movement substantially longitudinally of the barge along said platform;
said crane means including means for lifting, transferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said crane means along the barge platform a predetermined distance when said barge is in said high~draft semi-submerged operating condition will cause change in the angle of trim of the barge exceeding about plus or minus one-half degree as compared to the barge angie of trim prior to such longitudinal movement of the crane means absent sufficient counter-correction of such change in barge trim angle caused by such movement of said crane means; ballast means for counteracting the change in angle of trim of the barge caused by movement of said crane means longitudinally along said platform to maintain the angle of trim of said barge within an angle of change about the trLm axis of plus o, minus oné-half degree from such angle of trim existing prior to longitudinal movement of said crane means.
These and other related objects and advantages of the ~ -8B-,:`.. ,' : , -, ~ , 1(~3~;8 present invention will become more ~pparent upon reference to the following specification, appended claims and drawings wherein:
FIGURE 1 is a side elevational view of a pipelaying barge constr~cted in accordance with the present invention with a transition segment illustrated i~ semi-submerged floating condition for pipelaying operations;
FIGURE 2 is a plan view of the pipelaying barge and transition segment shown in FIGURE l;
FIGURE 3 is an enlarged horizontal cross-sectional view of the barge taken generally about on line 3-3 in FIGURE l;
FIGURES 4 and 5 are enlarged sross-sectional views taken generally about on lines 4~4 and 5-5 respectively in FIGURE 3;
FIGURE 6 is a schematic view of one of the hulls of the vessel illustrating the ballast system therefor;
FIGURE 7 is a side elevational view of a pipelaying barge constructed in accordance with another embodiment of the present invention and illustrated in high draft pipelaying condition;
FIGURE 8 is a plan view of the pipelaying barge illustrated in FIGURE 7;

i r~.~ ,- ~8C-~V3 ~ 8 FIGURE 9 is an enlarged cross-sectional view o~ -the barge of FIGURE 7 taken generally about on line 9-9 in FIGURE 7;
FIGURE 1~ is a fragmentary horizontal cross-sectional view of the aft end of the barge and plan view of the forward end of the transi~ion segment;
FIGURES llA, llB, 11~ and llD are schematic illustrations of the pipelaying barge illustrating the change in the trim attitude of the vessel in response to longitudinal movement of the crane between stern and pitch axis and the ballast correc~ion to counteract the change in the angle of trim induced by crane movement;
FIGURES 12A, 12B, aT~d 12C are similar schematlc illustrations of the barge illustrating changes in the atti-tude of the barge in response to longitudinal movement of the crane between locations aft and forward of the pitch axis and ballast correction to maintain the attitude of ~he barge within the preset operational trim attitude;
FIGURE 13 is a graph which plots along the ordinate the distance from the hull top to load line draft called "LLD"
versus various barge column height "BCH" along the absicca;
and FIGURES 14A-14D are schematic illustrations of the pipelaying barge and transition segment (similar to FIGURES llA-llD and 12A-12C) and FICURE 14E is a schematic illustration in horizontal cross section through the columns;

i~39(~f~8 the loads, loci, distances, moments, axes, etc. designated in drawing FIGURES 14A-E, for example "CL","BMC", '~TA", etc are defined later in the specification for use in the appended claims with reference to drawing FIGURES 14A-E
(and other drawing Figures such as FIGURES 13 and 1 as discussed below).
Referring to the drawings, particularly to FIGURES 1 and 2~ there is illustrated a column stabilized, semi-submersible pipe laying barge or vessel constructed in accordance with one embodiment of the present invention and generally indicated 10. Barge 10 includes a pair of transversely spaced, elongated hulls 12 extending in spaced ~;
parallel relation and providing sufficient displacement to support barge 10 in a low-dr$ft floating condition with the hulls 12 having freeboard indicated '~" in FIGURE 1. Each hull has a bow suitably shaped to reduce resistance to movement of barge 10 through the water when it is moved in the low-draft floating condition. Each hull 12 is also substantially rectan-gular in cross section with parallel planar top and bottom surfaces extending substantially the entire length of the hull for reasons discussed hereinafter; it will be appreciated, however, that each hull cross section may have rounded corner edges and that the sides of the hulls may be arcuate, i.e.
laterally outwardly conve~ in shape between the top and bottom hull surfaces.

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1039~8 A platform generally designated P and comprising a main deck 16 and a lower deck 18, is supported a predeter-mined height above the hulls 12 by support structure including a plurality of longitudinally spaced transversely extending truss formations generally indicated 20 and 30 and a plurality of longi~udinally spaced pairs of transversely spaced stabilizing columns 22. As illustrated in FIGURE 1, a plurality of the truss formations 20 are longitudinally .
spaced between each longitudinally spaced pair of columns 22 and each such truss formation includes as illustrated in FIGURE 5, two outermost support members 24 upstanding from the outer side of each hull 12 to the outer edges oflower deck 18; a plurality of diagonal or inclined beams 26 secured between each hull 12 and lower deck 18 providing support for platform P; and a transversely ex~ending horizontal cross beam 28 joining the upper inner sides of hulls 12 one to the other. A truss formation 30 connects between hulls 12 in the area between each pair of transversely .
adjacent columns 22 with two such truss formations 30 being ; ;
located between the fore and aft pairs of columns 22, As illustrated in FIGURE 4, each truss formation 30 includes beams 32 inclined from the interior edges of the hulls toward one another for connection to the lower deck 18 of platform P
and a transverse horizontal cross beam 34 joining the upper inner sides of hulls 12 one to the other. Additional vertic- -ally extending support members 35 also structurally inter-connect hulls 12 and platform P. ~:

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The truss formations 20 and 30 rein~orce the structural relationship of the hulls, platform and columns and restrain, particularly by means of the cross beams 28 and 32, the hulls 12 against lateral displacement re~ative to one anotherO ~ -As discussed more fully herelnafter, the support structure also includes stabilizing columns 22 which extend upwardly from the upper surfaces of hulls 12 to platform P ~
a predetermined height, preferably greater than the maximum - `
anticipated wave height (i.e. the vertical distance between wave crest and trough). In the preferred embodiment, four pairs of columns 22 are equally longitudinally spaced one from the other along hulls 12 with the column arrangement on each hull being symmetrical with respect to the column arrangement on the other hull, As shown in FIGURE 3, each column 22 is generally oblong in shape and is arranged such that the long axis of its cross section lies parallel to the longitudinal centerline of the barge. Each column 22, as illustrated in FIGURE 3, has longitudinally transver~ely spaced inner and outer vertical sides and semi-cylindrical ore and aft vertical end sections 36, The columns, however, may have circular, square, octagonal, elliptical or other horizontal cross-sectional configurations and need not have e~ual cross-sectional areas as illustrated herein, Symmetry of the cross-sectional areas of the columns about the pitch and roll axis of the barge is preferred.

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1(13~68 However, it is important that each column 22 have a constant cross-sectional area at least for the intermediate portion of the column which extends vertically from a point located 0 25 of the total column height above the hulls 12 to a point located 0 75 of the total column height above the hulls (the latter point being 0 25 of the total column height below the platform P) That is, the middle half of each column 22 is constant in cross-sectional area; preferably, the columns 22 are constant in cross-sectional area throughout their entire length, but either or both the upper and lower ends of the columns may have different cross sections, for example, to facilitate structural connection between the columns 22 and the hulls 12 ~nd platform P providing such different cross sections are of a configuration which do not adversely affect the operating characteristics of the barge when in high draft semi-submerged condition for pipelaying as amplified hereinafter. Preferably~ the columns are located along the outboard sides of hulls 12 such that the outboard vertical sides of the columns 22 form vertical extensions of the outboard sides of the hulls, as illustrated in FIGURES 3 and 4. The centroids of the cross section of the columns are also preferably located outboard of the center-line of each hull 12 and thus in the high draft semi-submerged condition of the barge provide increased moment of inertia of the water plane areas about the roll axis affording improved stability characteristics about the roll axis, -13- :

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particularly for a barge o~ the present type which has a high length to width ratio as set forth her~inafter. While four pairs of columns are illustrated, it is possible ~o use at least three pairs of columns or more than four pairs of columns, depending upon the desired stability and motion characteristics and other design parameters; three pairs of columns are minimum for such a pipelaying barge.
Referring now particularly to FIGURE 2, a pipeline assembly ramp 40 is disposed along one side of platform P and extends generally horizontally along the forward portion of the barge while declining along the aft portion of the barge !~ as indicated at 41 (see FIGURE 1) such that the ramp termin-ates substantially at the stern of the barge at an elevation 3 corresponding substantially to the elevation of the second deck 18 of platform P At the forward end of ramp 40 there is provided a pipe section line-up station 42 for receiving pipe sections from a transverse conveyor 44 which, in turn, receives pipe section from a longitudinal conveyor 45 which extends longitudinally parallel to ramp 40 along the inboard side thereof. Sections of pipe are stored in discrete longitudinally aligned pipe storage areas 48, a plurality of :ri such pipe storage areas 48 being spaced longitudinally along the opposite side of barge 10 from ramp 40 and also spaced ~l along the longitudinal centerline of the barge. A plurality `: of pipe support means 50 including pipe rollers are longitud-inally spaced one from the other along ramp 40 for support and . .
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movement of the pipe sections and pipeline to be laid. Between such pipe suppor~ stations are a plurality of welding stations 51 for successively welding by any suitable known means the joints between longitudinally aligned pipe section as the pipeline is payed out from the barge. Further along ramp 40, there is provided a plurality of longitudinally spaced tensioners 52 each comprising upper and lower caterpillar-type treads, rolls or equivalent means which engage and grip the pipe to maintain a predetermined tension on the pipeline as it is payed out from the barge (in a manner known in this ;
industry). Additional welding stations are located between each longitudinally adjacent tensioner 52 and a final welding station is loca~ed just aft of the furthest aft tensioner 52.
A plurality of additional pipeline supports 54 are longitud-inally spaced along declining ramp 41 aft of the tensioners 52, The pipeline supports 50 on the forward part of ~he barge are preferably arranged vertically so that the pipeline section carried by these supports lies along a substantially straight line slightly upwardly inclined (in direction toward the bow of the barge), at a suitable angle, e.g., on the order of ~wo -degrees. A plurality of aft pipeline supports 55 are arranged to support the pipeline section therealong a curve forming an ,~
initial portion of the pipeline overbend where the pipeline curves downwardly for entry into the water. Additional pipe-line work stations are spaced between tensioners 52 and supports 54 and include x-ray and dope stations.

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1~3 ~ 8 A helideck 56 is located at the forward end of the barge and overlies the transverse conveyor 44, the forward end of the longitudinal conveyor 46, and the pipe line-up station 42. Also illustrated in FIGURE 2 is a pair of anchor winches ;
57, which form part of an anchoring system, including additional anchor winches, not shown, located adjacent the stern portions of the barge. In a preferred form, the anchoring system includes lO anchors and associated anchor lines, winches and other ancillary equipment; and, as discussed more fully below, such anchoring system enables three anchors to be set off each bow quarter and two anchors off each stern quarter.
Along the side of the vessel opposite pipe laying ramp 40, there is provided a gantry crane, generally designated 60. Transversely spaced tracks 62 are provided along platform P, and these tracks extend longitudinally substanti-ally the entire length of the vessel platform P, and thus substantially the entire length of barge lO, as illustrated particularly in FIGU~E 2. Gantry crane 60 includes a pair of transversely spaced support trusses or legs 64, each being mounted on a pair of longitudinally aligned trucks 66 at each ;~-of its forward and aft extremities. Trucks 66 are engageable with the rails 62 and gantry crane 60 îs thus movable longi-tudinally along tracks 62 over substantially the entire length of the platform P and barge and at least between longitudinal positions adjacent each of the end columns 22. Gantry crane 60 also includes a rotatable cab 68, supported by trusses 64 :.~, . . . . .............................. .

, ~;: - : , 1~3 ~(~6 and trucks 66, at the upper end of trusses 66, and cab 6 carries a crane boom 70 for rotating movement with the cab about a substantially vertical axis by operation af power means not shown, Gantry crane 60 is movable by suitable motors, not shown, along tracks 62 to selected longitudinal positions along barge 10 to perform lifting operations at such longitudinal positions including the transfer of pipe sections from supply boats to either the pipe storage areas 48 along platform P or directly to the pipe transfer and line-up equipment 44 and 46 for loading pipe sections directly into the plpe assembly line.
Gantry crane ~0 is also useful for lifting operations in connection with the stinger or other pipe transition element generally designated T in FI~URE 1 and described below and for general purpose lifting, transferring and setting of loads about the barge, More particularly, the cab of gantry crane 60 is rotatable such that boom 70 overlies the barge or the one side of the barge along which the gantry crane is mounted for lifting operations off such one vessel slde and off either end of the barge, depending upon the longitudinal location of the gantry crane along the barge. Gantry crane trusses 64 straddle the pipe storage areas 48 along the one side of the barge.
Thus longitudinal movement substantially the entire length of the barge is not inhibited by the pipe sections stor~ in pipe storage areas 48 and increased deck load and storage capacity for the pipe sections are thereby achieved without impairing operation and use of the crane at any longitudinal position along the barge.

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The gantry crane 60 can be located adjacent the stern end of the platform P with the gantry trucks 66 locked to fix the gantry crane 60 at such position and gantry crane 60 is a heavy ~ -duty crane of such size ~nd capacity with cab rotatable about a substantially vertical axis with boom 70 which is of such length and capacity whereby gantry crane 60 is capable of performing lifting operations for heavy loads off the end of the barge adjacent which the gantry crane 60 is thus mounted and also off at least the beam of the barge along which the gantry crane 60 is thus mounted. This would be done for example to service the transition segment T extending from the stern of the barge 10.
As seen in FIGURE 6, hulls 12 are each di~ided into longitudinally and transversely spaced compartment~ 76 forming a plurality of ballast chambers for submerging and refloating the barge; any suitable number of compartments 76 may be ~ ,.
provided as desired to perform the intended ballasting function, While only the starboard hull and ballast system for same is illustrated in FIGURE 6, it will be understood that the port hull is similarly arranged and ballasted but on the opposite hand. Ballast chambers 76 are selectively and independently ballasted and deballasted whereby the hulls andlower portions of the columns may be submerged with platform P remaining substantially level throughout the submergence thereof and any at~itude deviation of the barge in both heel and trim may be corrected during change of draft between low and high draft conditions and retention of the vessel in the high draft condition. -18-1 03~1~6 8 Ballast chambers 76 may also be selectively and independently ~ -or dependently ballasted and deballasted when the barge is in high draft semi-submerged pipe laying condition as described below to provide a change in attitude of the barge about its trim axis and thereby satisfactorily proceed with pipelaying operations, particularly in conjunction and correlation with gantry crane operations as below described. To these ends, a plurality of conduits 77 extend from a pump room PR in each of the hulls 12 in opposite longitudinal directions to the several ballast compartments 76, there being multiple compart-ments in the forward and aft portions, respectively, of each hull. Pump room PR is provided with a sea suction inlet indicated at 78 and an overboard disch~rge indicated at 79 controlled by suitable power o~erated gate valves 80 and 81 respectively, the hull side being indicated by the dashed lines in FIG7~RE 6 A pair of pumps 82 and 83 are connected in parallel via lines 84 and 85, respectively, across conduits 86 - and 87, conduit 86 connecting with inlet 78 and conduit 87 ~ :
connecting with discharge 79. Conduits 86 and 87 connect with a conduit 88 and it will be seen that, with valves 89 and 90 closed, pumps 82 and 83 suction sea water through inlet 78 past suitable valves 9l located in the parallel pump lines 84 and 85, and into conduit 87 which, with valve 81 closed, communicates with the main ballast conduit 92 which are connected in parallel with ballast compar~ments 76 through a pair of power operated valves 93 located on opposite sides of . . . " . . .- , , -: ~ . -, . .
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feed conduît 87, ballast conduits 77 each having a suitable power operated valve 94, Thus, with valves 80 3 91 ~ 93 and 94 open and valves 81, 8g and 90 closed, the ballast compartments may be simultaneously ballasted with sea water at an equal rate to maintain the plat~orm substantially level when the hulls and column portions are being submerged or the valves 94 may be selectively operated to control the ballasting of the individ-ual compartments 76 whereby the trim and/or heel of the vessel may be corrected or altered during submergence or raising of the vessel and especially in the semi-submerged high draft condition during pipelaying operations, and particularly in correlation to and adjustment of longitudinal movement, locat-ion and/or load o~ the crsne 60 as hereinafter descri~ed, ~ine ~
88 is used to transfer ballast between one hull and the other.
Opposite ends of conduit 86 connect conduits 92 through suitable power operated valves 90 which the pumps 82 and 83 suctions, The pumps 82 and 83 discharges are connected through valves 81 to the overboard discharge at 79.
To alter the draft of the barge from its high draft condition to the low draft condition with the hulls 12 having freeboard "f", valves 80 and 93 are closed a~d valves 81, 90 and 91 are open. Pumps 82 and 83 operate to pump water in the same direction as before, and accordingly, suction from conduits 92 via conduit 86 thereby suctioning ballast conduits 77 through valves 94 withdrawing ballast water from compart-ments 76 ViR conduits 77, 92 and 86, the pump lines 84 and 85, , ~ open valve 81 and outlet 79.
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~039(~

With appropriate valves 94 open, compartments 76 may be deball-asted as required to return the barge to its low draft condition whereby the mean waterline with respect to hulls 12 is located along a line shown at llfll in FIGURES 1 and 7 so that hulls 12 have freeboard above "f" in this low draft floating condition Selected operation of valves 94 with valves 81 and 90 open and valve 80 closed deballasts selected compartments 76 as desired to alter the attitude of the vessel about the heel and/or trim axis as necessary or desirable and particularly ~o enable successful pipelaying operations as hereinafter described. It is thus readily seen that compart-ments 76 may be simultaneously ballasted and deballasted or selectively ballasted and deballasted or have ballast trans-ferred between the port and starboard hulls by selected operation of the various valves and that this can be accompl-ished when the barge is in any operating draft, for example, in low draft floating condition with the hulls having freeboard (i e. mean waterline at about "f" in FIGURES 1 and 7), semi-submerged high draft floating condition, or any other inter-mediate draft condition during barge operations, whereby the ~-attitude of the barge about heel and trim axis can be altered in such different draft conditions Note also ~hat the various valves, conduits, etc. of the foregoing ballast system are provided for each hull 12 whereby one or both hulls may be : ballasted or deballasted alone or together or ballast trans-ferred from one hull to the other -~
., ~ 03 ~6 8 In the disclosed and described embodiment of the present invention, the barge has an overall length of 400 feet at hulls 12, with each hull having a beam of 34 feet, a height of 20 feet and an inside spacing of 38 feet one from the other, thus providing an overall hull beam of lQ6 feet between outer sides of the two hulls 12, Thus, this embodiment has a length to width ratio of about 4 to 1 and should have a length to width ratio of at least 2,5 to 1, The height of the columns 22 is 23 feet. The centroids of the columns are equally spaced 39 feet from the vessel's longitudinal centerline. The pairs of columns are longitudinally spaced one from the other 63.25 ~eet with the bow pair of columns being spaced 19.75 feet from the orward extremities of the hulls 12. The length of each column is 46 feet and its width is 28 feet with the ends thereof being formed cylindrical in shape providing an overall column area of approximately 1119.5 square feet per column.
The light ship displacement of the vessel in low draft condition is approximat~ 10,000 tons while the loaded displace-ment in high draft condition is approxi-~ately 21,800 tons.
The weight of the gantry crane 60 may approximate 400 tons unloaded and has a capacity for lifting heavy loads on the order of 80 tons.
The pipeline transition segment T is releasably secured to the stern of barge lG by a pivotal connection 74 and serves to support the "air length" portion of pipeline "payed out" from the barge and extending between the stern of ;

1~35~Q68 the barge and the waterllne plus a portion of the pipeline extending below the waterline, The pipel~ne transition segment T may comprise one or the other of the "stingers" shown and described in aforementioned U, S, Patent Nos, 3,704,596 and 3,685,305 the disclosures of which paten~s are incorporated herein by reference as though fully set forth herein, .
Briefly, the disclosed pipeline transition segment T is a column stabilized variable draft type stinger which ~ncludes a generally triangularly or rectangular shaped base or hull structure generally designated 100 including a pair of transversely spaced pontoons 101 and a depending keel 102, : :
pontoons 101 and keel 102 being arranged in triangular or rectangular cross section and connected by suitable webs 103, The forward end of hull 100 includes laterally spaced hinges 104 which cooperate with hinge structure carried at the stern of the barge hull underlying the pipeline ramp whereby pipe-line transition segment T is pivotally secured to barge 10, Pipeline transition segment T also includes a plurality of upstanding st~bilizing columns 105 secured to each of the upper pontoons 101, the columns 105 being arranged in longitudinally spaced pairs, A plurality of pipeline supporting carriages, not shown, are mounted between the pairs of columns 105 and include rollers disposed in a fore and aft direction along the arc of the curve the pipeline will take in the overbend region and enable translatlonal movement of the pipeline relative to the transition segment T~

.... . . ,. .. . ~
.:. . . ~ ; :-~, ~. ,, .~ , , , ;~ . . ~ . . ~ -~03~06~ `
Referring to FIGURES 1, and 11 A-D and 12 A-C, the pipeline transition segment T thus supports the pipeline schematically shown at PL as it is payed out from the barge in a manner such that the radius of curvature of the pipeline portion indicated at PLC in said Figures is always greater than the radius of curvature which would cause bending stresses ex-ceeding maximum allowable bending stresses for the pipeline and/or the protective coating generally applied to such pipe-line. The pontoons lOl are compartmented to form a plurality of ballast cham~ers which can be independently and dependently ballasted and deballasted from the barge lO. The pipeline transition segment T thus has the ballast capability to alter its draft between a low draft pontoon supported condition and a high draft semi-submerged floating condition wherein the waterline lies intermediate or above the height of columns 105 and also to change ~he attitude of the pipeline transition segment T about trim and heel axes by ballasting and/or de-ballasting selected compartments in the pontosns 101.
Turning now to the embodiment of the pipelaying barge illustrated in FIGURES 7-lO, the basic construction and config-uration is like that of the previously described pipelaying barge of FIGURES 1-6, but with several changes including: an increase in vessel beam to provide increased deck-load capacity, on the order of three times more deck-load capacity; an ~ncrease in the depth of the hulls and columns to provide the necessary hydrostatic characteristics for such deck-load;

,. . ~ ;
.
.. ~ , ~39~68 and modification to assemble and weld the pipeline along the centerline of the barge rather tnan along a side, thus enabling use of a symmetrical transition element T' (shown in FIGURE 10 for this embodiment) and minimizing effects of vessel roll on the pipeline PL, Furthermore, this pipelayer barge embodiment with centerline pipelaying feature also includes an inclined :
ramp so that the angle of entry of the pipeline into the water is improved and the "air gap" segment of pipeline between the barge stern and water line is much smaller thus enabling use of a smaller and sometimes a simpler pipeline transition seg-ment T' than would otherwise be necessary. Other differences as between this and the previously described pipelaying barge embodiment will become apparent from the following description of this second embodiment.
Referring now to FIGURE 7, barge 110 includes a pair of transversely spaced elongated hulls 112 extending in spaced parallel relation and providing sufficient displacement to support barge 110 in the low draft floating condition with the hulls having freeboard whereby the mean water line is along line "f" indicated in FIGURE 7. As in the previous embodiment of FIGURES 1-6, the bow of each hull 112 is stream lined to reduce resistance to towing when barge 110 is en~irely supported in low draft condition on hulls 112, Each hull 112 is substantially rectangular in cross section, as :
particularly illustrated in FIGURE 9, although the edges of the hulls can be rounded and the sides arcuate and the hulls . . . ~
.
~, . . . . -.. . . .
. . , .. .. ~ .
.; . . . .

1(339~ 8 otherwise specifically shaped as previously ~lescribed with respect to the prior embodiment of FIGURES 1-6. The hulls 112 each have top and bottom substantially parallel and substanti-ally planar surfaces extending su~stantially the entire length of the hulls for reasons noted hereinafter.
A platform P' comprising a main deck 114 and a lower deck 116 is supported a predetermined height above hulls 112 by support structure including a plurality of longitudinally spaced, transversely extending truss formations generally indicated 118 and a plurality of longitudinally spaced pairs of transversely spaced stabilizing columns 120. A truss formation 118 is longitudinally spaced between each longitudin-ally spaced pair of columns 120 and the truss formation between the longitud;nally spaced pairs of columns is similar to the truss formation previously described in the prior embodiment with respect to FIGURE 5. As illustrated in FIGURE 9, addit-ional transverse truss formations 122 are locatod in the areas between the hulls in transverse alignment with the longitudin-ally spaced pairs of columns 120. This latter trussf~rmation is similar to the truss arrangement illustrated in FIGURE 4, Both truss formations in this embodiment (as in that of FIGURES 1-6) also include horizontally transversely extending cross braces joining the upper inner sides of hulls 112, one to the other, to reinforce the structural relationship of the hulls, platform and columns~ and to restrain the hulls against lateral displacement.

,~ . . .
- ~ , .

1035~(~68 As in the previous embodiment, the support structure also includes stabilizing columns 120 extending upwardly from the upper surfaces of hulls lL2 to platform P' an effective height which may be equal to and preferably greater than the maximum anticipated wave height, i.e., the ver~ical distance between wave crest and trough In this embodiment, four pairs of columns 120 are equally longitudinally spaced one from the other along hulls 112 with the column arrangement on each hull being symmetrical with respect to the other hull However, at least three pairs of such columns or more than four pairs of such columns, longitudinally spaced one from the other, may be utilized, with three such pairs of columns being considered the minimum, as discussed above with reference to the embodiment of FIGURES 1-6. As shown by the dashed lines in FIGURE 8, columns 120 are preferably generally oblong shaped with longitudinally elongated vertical sides and semicylindrical fore and aft vertical end sections.
However, as discussed with reference to the embodiment of FIGURES 1-6, such columns 120 may have circular, square, octagonal or other cross-sectional configurations Columns 120 should be constant in cross-sectional area for that portion of their height which extends from a point located 0 25 of the column height above the top of each hull 112 to a point located 0.75 of the column height above said hulls (or 0.25 of the column height from the bottom of the platform P') Also, as discussed for the embodiment of FIGURES 1-6, columns 120 10390f~8 preferably have constant cross-sectional area throughout their height, but the section of the columns at the connect~ons between the lower and upper ends of the columns with the hulls and platform respectively may be varied to provide for mechanical and structural interconnection providing such different cross section does not have an adverse effect on the hydrostatic and other operating characteristics of the barge.
This embodiment of pipelaying barge 110 is provided with a pipelaying ramp 136 substantially along the longitudinal centerline of the barge, along which a pipe assembly line generally designated 138 is provided, Pipe storage areas 142 are disposed at various longitudinally spaced locations along each of ~he opposite sides of the barge 110 on opposite sides of pipe assembly line 138 and pipe sections may be transferred from the pipe storage areas 142 onto longitudinally extending conveyors 144 which flank the pipe assembly line 138 and which conveyors 144 are adapted to transport the pipe sections forwardly to pipe transfer and line-up equipment 146 located at the forward end of pipe assembly line 138. The pipe trans-fer equipment 146 includes transverse conveyors for transferr-ing pipe sections from the long~tudinal conveyors 144 transversely of the barge into alignment with the pipe assembly line 138 and the pipeline extending longitudinally therealong and generally along the longitudinal centerline of the barge.
The pipe transfer conveyor 146 and the forward end of the pipe assembly line 138 is carried on a cantilevered extension of . . --1~39~1~6~3 ~

platform P' which projects forwardly from the bow of the barge (see FIGIJRES 7 and 8). Thîs cantilever extension also includes a helideck 160 spaced above the pipe transfer and alignment equipment 146. A plurality of longitudinally spaced welding :
statîons 147 are located along pipe assembly line 138 and additionally between longi~udinally adjacent pairs of pipe tensioners 148; any known suitable welding system may be used at such station. Additionally, dope and x-ray stations are located aft of the aftmost pipe tensioner 148. As will be appreciated from a review of FIGI~RES 7 and 8, the ramp 136 includes a forward portion 150 of the main deck 114 and an elongated central well 152. The lower surface 154 of well 152 inclines downwardly and ln an aft direction and provides a support surface for mounting the tensioners 148 The well 152 communicates at the aft end of the barge with a tunnel 156 which exits from the barge between the aft pair of columns 120 and enables the pipeline PL to be discharged from the barge at an elevation much closer to the waterline than possible with prior embodiments such as that for FIGURES 1-6. Dope, x-ray, and final coating stations are carried by a deck 158 which, in part, defines part of tunnel 156. As in the e~bodi-ment of FIGURES 1-6, various pipe support means with rollers (not shown) are spaced longitudinally along the ramp, with the pipe support means located on the ~arge forwardly of the tensioners supporting the pipe along a generally straight line while the pipe support means located on the barge aft of the tensioners 148 support the pipe along a genPrally downwardly ... ,.. .. . , . . . . . ~
,',' : , , ;: . . . . . ;

1~3 ~ 8 curved line. Also, as in the prior embodiment, the slope of the straight portion of the pipeline is adjustable by adjust-ment of the eleva~ion of the rollers, not shown, at each of the pipe support means and preferably the straight portion of ~he pipeline is inclined upwardly towards the bow of the barge at a desired angle, namely, about 3.5 degrees from horizontal (see Angle B in F~GURE 7) to provide a good angle of entry of the pipeline PL into the water including a good pipeline curvature at pipeline segment PLC.
In this embodiment, a pair of gantry cranes 162 and 164 are mo~ted for longitudinal movement along opposite sides of barge 110 on pairs of transversely spaced rails or tracks 166 which extend substantial;y the entire length of the plat-form P' and barge 110. Gantry cranes 162 and 164 of this embodiment are each similar to gantry crane 60 of the prev-iously described embodiment of FIGURES 1-6; each such crane includes lower transversely spaced longitudinally extending trusses 168 which support a crane base or pedestal 170, the lower ends of the side trusses 168 being supported on gan~ry crane trucks 172 which engage tracks 166. Each gantry crane 162 and 164 includes a cab 174 rotatable on base 170 about a generally vertical axis and carrying a boom 176. Referring especially to FIGURE 9~ as in the gantry crane 60 of the embodiment of FIGURES 1-6, each pair of crane side trusses 168 are transversely spaced one from the other such that the side trusses straddle the pipe storage areas 142 . -~(~3 9(~6 8 longitudinally spaced along each of the opposite sides of the barge enabling longitudinal movement of crane 162 and 164 along tracks 166 for location at substantlally any longitud~
inal position along barge 110. It will be appreciated that each gantry crane 162 and 164 has sufficient capacity and a boom of sufficient outreach to perform lifting operations out-board of the side of the barge on which the gantry crane is mounted, as well as off either end of the barge depending upon the longitudinal location of the crane along the barge. As in the prior embodiment, the cranes are utilized for lifting operations off one side and either end of the barge including the transfer of pipe sections from supply boats onto the ;
storage areas 142 or directly onto the longitudinal conveyors 144 and for general purpose lifting operations aboard the barge Each gantry crane 160 can be located adjacent the stern end of the platform P' with the gantry trucks 156 locked to fix either gantry crane 160 at such position, and each gantry crane 160 is a heavy duty crane of such size and ~ .
capacity with cab rotatable about a substantially vertical axis and with boom 176 which is of sufficient length and capacity whereby such gantry crane 160 is capable of perform- ;
ing lifting operations for heavy loads off the end of the ~ :
barge adjacent which such gantry crane 160 is thus mounted and also off at least the beam of the barge along which such gantry crane 160 is thus mounted. This would be done for example to service the transition segment or stinger T' extending from the stern of the barge 110.

, , , - ... - , - , .. . .
.. . .

ia~3906s The hulls 112 of this embodiment of FIGURES 7-10 are compartmented and ballasted and deballasted similarly as described above with respect to e~bodiment of FIGURES 1-6. It is believed sufficient to summarize here that such ballast system has the capability to ballast the barge 110 between low draft floating condition with hulls having freeboard and semi-submerged high draft operating condition and can selectively ballast and/or deballast any part of such ballast system to alter the attitude of the barge about trim and heel axes as desired and for the purposes set forth herein.
In a suitable pipelaying barge embodiment per FIGURES
7-10, the barge can have an overall length of 460 feet at hulls 112, with each hull having a beam of 40 feet, a height of 23 feet and an inside spacing of 50 feet one from the other providing an overall hull beam of 130 feet between the outer sides of hulls 112. The height of the columns 122 is 25 feet so that tne height from keel to the underside of the platform is 48 feet. In this embodiment, the barge has a len~h to width ratio of ae least 2.5 to 1. The centroids of the columns 122 are equally spaced 50 feet from the vessel's longitudinal centerline. The pairs of columns are longitudinally spaced one from the oeher 128 feet with the bow pair of columns being spaced 38 feet from the fon~ard extremities of the hulls 112.
The length of each column is 50 feet and its width is 30 eet with the ends thereof being formed cylindrical in shape pro-~iding an overall column area of approxima~ely 1706.5 square feet per column.

~(39~:~6~

The light ship displacement of ~he vessel in low draft condi-tion is approximately 12,000 tons while tne loaded displacement in high draft condition is approximately 30,000 tons. The weight of each gantry crane 162 and 164 may be approximately 400 tons and has a capacity for lifting loads up to about 80 tons The GM of this barge is about 4 feet The pipeline transition segment T' may be a column-stabilized stinger of such type as disclosed in U. S. Patent No. 3,685,305 and particularly with respect to FIGURES 11-13 thereof, with the transition segment or stinger T' being pivotally hinged to the stern of both hulls 112 as illustrated in FIGURE 10 hereof Further description of the particular transition segment or stinger T' is not believed necessary; it i8 sufficient to note that such transition segment or stinger T' includes a hull having a plurality of longitudinally and transversely spaced ballast compartments which can be selectively ballasted and deballasted to alter the draft of the pipeline transition segment between high and 10W draft conditions, and also to alter the attitude of the pipeline ~
transition segment T' about heel and trim axes as desirable `
and especially in trim to control the curvature of pipeline segment PLC within desired limits.
For lifting, transferring and setting loads, in both embodiments of the pipelay barge hereof, crawler-type cranes without rails fixed to the platform may be utilized in lieu ; of gantry type cranes.

1: .. .
. . .

103 ~(?6 ~
Each crawler crane would include a ro~atable cab and boom operable similarly as described above with respect to the gantry crane in conjunction with the below described construc-tional and operational features of the semi-submerged pipe-laying vessels including correlation of ballast with crane movement, location and/or load which is applicable to both types of cranes when used in analogous manner.
In use, the pipelaying barge hereof is moved (by means not shown) in a low draft floating condition with the hulls having mean water line at "f" so the hulls have freeboard and can be efficiently moved at speeds on the order of ~ to 10 knots providing the present vessel with high mobility for transit between work sites located in different dis~ant locations of the world The barge can be efficiently towed by available tugs; or it can be provided with propulsion machinery whereby it can move from site to site under its own power, if desired. At the work site, the pipeline transition segment is coupled to the pipelaying barge by the described hinge connection, the transition segment being generally towed or transported to the work site by a separate vessel.
In this connection, the crane or cranes on the pipelaying barge are located adjacent the stern end of the barge to connect the barge and pipeline transi~ion segment and/or otherwise service the latter.
At the work site, the ballast compartments of the -~
barge 10 (or 110) and in the pipeline transition segment T

. . . .

~ O~ 9 O ~ 8 (or T') are simultaneously ~allasted to submerge their respective hulls and pon~oons The barge 10 (or 110) is ballasted so that the columns of the barge are submerged at ~ -least 0.25 the height of the columns above the hull ~ops, and pre~erably about 0.5 the height of the columns.
Referring to FIGURE 13, that is a graph showing ~he permissible range of distance between the top of the twin ;
hulls 12 (or 112) of the pipelaying vessel 10 (or 110) and the mean water line at "load line draftt' of the pipelaying vessel in semi-submerged fLoating condition dependent on varying column height, for construction and use of pipelaying barges utilizing the present invention. "Load line draft" ls the maximum permissible high draft position for such a pipe-laying vessel, and FIGURE 13 shows along the ordinate the distance from the top surface of the hulls 12 (or 112) to the ;~
mean waterline constituting permissible "load line draft" for pipe laying vessels 10 (or 110) having different heights of columns 20 (or 120) shown along the abscissa. An envelope bounded by maximum and minimum curves designated A and B
constitutes the range in load line draft condition with respect to given different column heights varying between a minimum column height of about 20 feet and a maximtlm column height of up to about 80 feet. The optimum operating draf~
for a given height colt~mn is also illustrated by the curve designated at C within the maximum and minimum envelope curves A and B.

-.. .. - .- .. ~ ~ ; , 103~106f~
The location of ~he mean wat~r line above the vessel hulls 12 (or 112) and in relation to the height of the columns 20 (or 120) is determined according to the foregoing ~or the pipe-laying barge 10 (or 110) when it is in semi-submerged high draft floating condition for pipe laying operations. As further amplified below, the columns of .he pipeline transition segment or stinger T (or T') are thus submerged according to extent of submergence of columns of the barge 10 (or 110).
Additionally, the pipeline transition segment T (or T') is ballasted to establish its own trim angle to a desired angle suitable for laying pipe of given size in the specified depth of water with a predetermined configuration of curved pipeline section PLC.
For most pipelaying operations, the trim of the barge 10 (or 110) is set a predetermined trim angle to improve the angle of entry of the pipeline into the water; and usually the barge 10 (or 110) will be ballasted to provide a preset operational barge trim angle within a range from 0 to 2 5 degrees from horizontal, and preferably about 1.5 degrees, with the bow end of the barge tilted upward. When the barge 10 (or 110) is in semisubmerged column stabilized condition, with the mean waterline above the hulls as herein described, such columns provide righting moments about pitch and roll axes ~o provide requisite barge s~ability consistent with requisite motion-minimizing characteristics also ~039(~68 Particularly, the barge 10 (or 110) has a construction such that the configuration and area of the columns and the number of columns, and distances of the columns from the longitudinal and transverse centerlines of the barge are such to provide greater righting moment about the barge's transverse pitch axis than the righting moment about the barge's longitudinal roll axis when the barge is ln high draft semisubmerged pipelaying condition, The substantially parallel planar top ~`
and bottom surfaces of the hulls as above described provide mass damping when the barge is in high draft column stabilized ~ ~
condition; this inhibits vertical motion of the barge in heave, ;. :
and also inhibits net vertical displacement of the ends of the barge due to angular motion ln pitch, Still further, when the barge 10 (or 110) is in the high draft condition, the wave action is only against the columns and the trusses and the barge thus achieves substantial transparency to wind and wave action. Further, minimized motion, with requisite stability for the barge and pipeline transition segment combin-ation according to the foregoing embodiments, also is achieved by providing a low metacentric height ("GM"), for example about 4 feet, With the barge 10 (or 110) disposed in semi-submerged high draft floating condition with mean waterline above twin hulls 12 (or 112~ as above-discussed, the pipeline transition segment or stinger T tor T') hinged to the stern will be ballasted and submerged also as above-no~ed.

, ~:

103906~3 The column-stabilized stinger T (or T') is ballasted to establish a suitable trim angle of the stinger T (or T') at about 8-10 rom horizontal and tilted upwardly towards the barge as diagrammatically illustrated in FIGURES llA to llD
and 12A to 12C Most o~ the columns of the disclosed stinger T (or T') will be submerged below water line, generally except-ing only the first and possibly also the second pairs of stinger column(s) nearest the stern of the pipelaying barge The geometrical construction of the stinger and location of its pipe supporting rollers or equivalent means plus the angle of trim of the stinger in relation to size, draft and trim of the barge will determine the curvature of the pipeline extending from the barge stern over the pipe supporting stinger into the water and also to the sea bed at a given water depth.
When in high draft column stabilized condition for pipe laying as above discussed, the natural period of the . :
pipelay barge and stinger combination in roll is between about 25-30 seconds, in pitch about 20 seconds or more, and in heave about 16 seconds The motion responses of the pipelaying barge 10 (or 110) to wind and wave action are greatly minimized, especially with respect to change in attitude of the barge about its pitch axis as well as minimizing heave; this is important in pipe laying operations and specifically because ;
the curvature of the pipeline segment PLC extending from the vessel is highly affected by and sensitive to even small ~:

.. . . . . . .. . .

1(~3 9 O ~ 8 changes in the pipelaying vessel's angular disposition about pitch and trim axes. Once the attitude of the pipelaying barge about the trim axis is preset as above discussed, static trims of such barge should be limited to less than plus or minus one-half degree for the disclosed pipe laying arrangement.
Thus, the configuration, size and weight of the barge 10 (or 110) and its load distribution and especially the size, configuration, area, location and resultant righting moment of the columns about the pitch axis are designed in light of this severe limit of angular change of the pipelaying barge's attitude about the pitch axis To lay pipe when the barge is in the high draft column stabilized condition with preset operational trim, the pipe sections carried by the barge in the pipe storage areas are dlsposed onto the longitudinal and transverse conveyors for assembly and connection one with the other along the pipe assembly line. Particularly, the pipe sections are welded one to the other and the pipeline is payed out from the barge over the transition segment for entry into the water and final disposition on the sea bottom The tensioners maintain a predetermined tension on the pipeline as it is payed out and ~his, in conjunction with the transition segment, maintains the pipeline curvature within allowable stress limits and at or greater than the minimum radius of curvature. To pay out the pipeline, the barge and transition segment are advanced along the track of the pipeline along the sea bottom by 1039 0 ~ 8 hauling in the forward anchor lines and paying out the aft anchor lines. In relatively shallow wate-îs and using consid-erable lengths of anchor lines, the barge can be advanced in this manner 3000 and 4000 feet before the anchors are retrieved by anchor boats and reset It will be appreciated that with the foregoing described column stabilized barge and transition segment arrangement, the pipeline is payed out from the aft end of the barge at an elevation substantially above the mean waterline, for example, on the order of 15-50 feet. The transition segment thus supports the pipeline as it is payed out from the barge for the air length of the pipeline between the barge and the mean waterline and also a section of the pipeline extending some distance in the water while maintaining the curvature of the pipeline extending from the tensioners on the barge within the permissible stress limits and radius of curvature As noted previously, the angle of trim of the barge in semi-submerged high draft condition is a significant factor in pipelaying operations as it affects the pipe ^~
curvature in the pipeline segment PLC extending from the aft end of the barge. The pipeline extending from the barge stern over the pipeline transition element into the water and to and on the sea bed is somewhat "s-shaped" whereby the pipeline first assumes a concave downward curve or "overbend" -~
as it is payed out from the barge end and over the transition -40- ;

~ 039068 segment and then passes through a point of inflection at a location beyond the stinger and has an intermediate section which then extends to sea bottom and assumes a concave -;~
upward curve or "sagbend" as it is layed along the sea bottom `~
The pipeline is maintained as it is being ~aid within a ~-suitable percentage of the stress yield point of the pipeline for a given pipe as the pipeline is stressed in passing through the "overbend","inflection point" and "sagbend". For a given pipe, changes in the angular atti~ude of the barge about the trim axis beyond certain narrow limits will cause higher than allowable stresses which will break the concrete coating usually applied about the pipe which is unacceptable or will adversely overstress the pipe.
With respect to control of the attitude of the vessel in trim about the pitch axis, it is desirable to set a predetermined operational trim to improve the entry angle of the pipeline into the water and the attitude and curvature of the pipeline as it is payed out from the barge over the transition element and disposed along the sea bottom As previously noted, a bow-up operational trim is preferably set by proper ballasting ofthe vessel prior to commencing pipelaying operations; and, depending upon the pipe size and water depth, a preset barge trim of 0 to 2.5 degrees, and ; preferably about 1.5 degrees, is set by ballasting the barge as afore-described to alter its attitude to such a bow-up trim angle. With such a preset trim angle of the barge, ~ -41-. ., . : . .. - .

~ 3~ 8 a preset initial inclination of the pipeline of up to 10 from horizontal, but preferably up to 6 from horizontal bow-upward may be used; che latter degree of pipeline inclination from horizontal is the resultant of inclination of the pipeline with respect to the barge plus angle of trim of the barge about its trim axis With the barge in column stabilized semi-submerged condition for pipe laying, any change in attltude of the barge in trim should be maintained within an angle not in excess of plus or minus about one-half degree - 10 from the pre.set operational trim to avoid introducing a pipe curvature in the overbend which would introduce stresses and strains higher than allowable for the concrete coating about the pipe or for the pipe itself That is, it is necessary to maintain the attitude ~ the vessel in trim during pipe laying operations within plus or minus about one-half degree of the preset opera~ional trim which usually is within 0 to 2.5 degrees bow-up as discussed.
While the barge is designed to provide suitable righting moments about the pitch axis as determined by the configuration, number, areas and distances of the columns from the pitch axis, the geometry ~ the submerged hulls and lower column portions~ plus the weight distribution of the barge, which would maintain the angle of inclination of the barge about the pitch axis within plus or minus one-half degree during operations and in response to dynamic forces, -~
i.e. wind and wave action, the pipe laying operation onboard ..... , ~ . . i ~(~39(~68 the barge can and will introduce changes in the attitude of the barge in trim exceeding plus or minus one-half degree from the predetermined operational trim unless corrected.
For example, it has been found that the type, weight and operation of crane or cranes used on the semi-submersible pipelaying barge of this invention and the necessary longitud-inal movement of the cranes, either loaded or unloaded, introduces a significant change in the net moments about the pitch axis which will cause a change in the barge's attitude about the trim axis exceeding plus or minus about one-half degree from the preset operational trim. More particularly, it has been found that movement of a gantry crane 60 (or 160) longitudinally along the barge platform P a predetermined distance or greater will cause a significant change in the angle of trim of the barge when the barge is in high draft semisubmerged column stabilized pipelaying condition to such extent that if i~ were not compensated for the attitude of the barge about the trim axis would exceed plus or minus one-half degree of the present operational trim For example, with a pipelaying barge of the size and configuration illustrated and discussed herein and mounting a gantry crane weighing on the order of 400 tons for carrying loads of about 80 tons~
lo~gitudinal movement of the crane approximately one-quarter of the length of the vessel causes a change in the angle of trim of about one-half degree. The movement of such a gantry crane longitudinally along the barge on either side of the . ~ . .
. ................................... . .

103~6 ~

pitch axis, and also across the pitch axis, and the crane location before and after such movement, even when the crane is unloaded, thus becomes a significant factor a~fecting maintenance of the requisite attitude of the barge about the trim axis within plus or minus one-half degree of the preset operational trim of the barge before such crane movement, To compensate for the change in the angle of trim caused by longitudinal movement of the crane along the platform and thereby maintain the angle of trim of the barge within the stated allowable small angle of change from the preset angle of trim existing prior to longitudinal movement of the crane~
the barge 10 (or 110) is ballasted in response to and in ;~
correlation with longitudinai movement and location of the crane or cranes so that the angle of trim change induced by, during and after longitudinal movement of the crane with or without load does not exceed plus or minus one-half degree change from the preset angle of trim, The foregoing is diagrammatically illustrated in FIGURES llA-llD and FIGURES 12A-12C, in which drawings the ~-angles and Figures discussed below are exaggerated for clarity.
In FIGURE llA, the barge 10 (or 110) is illustrated in a horizontal position with 0 degree trim and a preset bow-up trim of 8-10 for the pipeline transition segment or stinger T, such attitudes of barge and stinger being accomplished by approprlate ballasting as previously discussed, Referring to FIGURE llB for the purpose of pro~iding a better angle of `.

,. . . .
.
- . . .: . . :
.. ~ . . . . . - .. .... ... . . . .
... - . . . . . -~139061~ `

entry of the pipeline into the water and to improve the attitude and curvature of the pipeline being laid, the barge 10 (or 1103 is set at an attitude having a bow-up preset operational trim angle of between 0-2.5 degrees, and preferably 1 5 degrees; and this is accomplished by selective ballasting and/or deballasting of the hull compartments as above discussed.
The transition segment is also ballasted to maintain its own desired trim angle relative to the barge and horizontal so as to maintain the pipeline segment PLC within proper curvature limits during all pipelaying operations. The discussed preset operational t-im angle of the barge (for example 1 5 degrees) is designated P.O.T in FIGURE llB which also illustrates a representative crane C located adjacent the aft end of the barge Longitudinal movement of the crane C, either loaded or unloaded, from its position adjacent the aft end of the barge shown in FIGURE llB for a certain distance, for example approximately one-quarter of the length of the vessel, to a location closer to the pitch axis, but with the axis of rotation of the crane (designated by the dashed lines in FIGURES llB and llC) still located on the aft side of the pitch axis as illustrated in FIGURE llC, will induce a change in the angle of trim of the vessel in excess of one-half degree unless compensated for during movement of the crane This is illustrated by the angle designated CMIT
(i.e., "crane movement induced trim") in FIGURE llC-, and in this instance the foregoing described crane movement causes a -~5-.- , i~3 9 ~ ~ 8 decrease in the previo~lsly set bow-up angle of trim EO~.which must be compensated for Consequently, for longitudinal move-ment of the crane a distance which causes a change in the vessel's trim angle exceeding one-half degree ~hange from the prior set trim angle, ballast correction of trim is necessary during and after the crane movement to counteract the resultant induced angle of trim change and maintain the attitude of the vessel close or equal to the preset operat-ional trim, and in any event within plus or minus one-half degree of the preset operational trim angle, consequently, the ballast system and crane movement are correlated one with the ~ ~:
other such that the crane movement induced angle of trim is offset or counteracted by ballasting. This is illustrated in FIGURE llD wherein the actual operating angle of trim of the vessel is illustrated close or equal to the predetermined operating trim angle and in any event at least kept within plus or minus one-half degree of the preset operational trim before crane movement It will be appreciated from a review of FIGURES llB
and llC that movement of the crane a like distance from the position just aft of the pitch axis illustrated in FIGURE llC
to a location adjacent the aft end of the barge illustrated in FIGURE llB would cause a similar change in the angle of trim of the barge in the opposite direction. ~hat is, if the preset operational trim is set with the crane located as illustrated in FIGURE llC, movement of the crane aft to a ... . . :- , ~, .
..... . - , - .
.~ . .. : . .
.;., , . . . .

~039~6 8 location as illustrated in FIGURE llB would increase the bow-up attitude of the vessel beyond the predetermined trim angle and exceeding one-half degree unless compensated for to counteract change ln trim angle during crane movement as discussed. This is illustrated in FIGURE lls by the dashed lines and angle CMIT'. This crane movement induced trim change must be offset by ballast correction in the opposite direction in order to maintain the barge attitude about its trim axis within about one-half degree of the preset operating trim, Such ballast corrections can be and are performed simultaneously with movement of the crane or in increments upon movement of the crane short distances thus enabling the ballast system to catch up with and counter the change in moment distribution caused by crane movement and avoid the change in barge trim angle which would thereby result if not .
counter-acted as discussed, A similar type correction is necessary when the crane is similarly longitudinally moved along the forward half of the barge, and also if the crane is moved similarly longitudinally fore and aft of the trim axis. Referring to FIGURES 12A-12C, the preset operational trim may be set with the crane located slightly aft of the pitch axis as illus-trated in FIGURE 12A. Movement of the crane forwardly to the posi~ion shown in FIGURE 12B would change the attitude of the vessel in excess of one-half degree from the present operational trim (if not counter-acted) in this case inducing ``', , . ~ , - . . : ~ , ~ ~3~68 a bow-do~ attitude designated CMIT in FIGURE 12B with respect to the angle P.O,T. Consequently, ballast correction in trim is necessary during such crane movement to maintain the barge attitude within one-half degree of the angle P.O.T., and this is illustrated ln FIGURE 12C which shows ballast correction having been applied so that the crane movement induces a change in angle ~ trim after ballast correction~ which angle is less than plus or minus 0.5 degree from the angle P.O.T., designated at CMIT in FIGURE 12C.
Following is a particular discussion of important ~:
features of t~e novel column stabilized semi-submersible barge ("SSB") and pipelaying combination including pipeline transit-ion segment ("PLTS") with reference being made to all drawings and description above, but with particular reference now made ..
to FIGURES 14A and 14E (plus FIGURES 13 and 1) which show and identify particular features and terms defined and amplified in numbered sub-paragraphs immediately following: :
(1) The length of the barge SSB along the barge . platform P is designated by l'BLP", and along the barge hulls by "BLH". The width of the barge SSB across the platform P is designated by ''BWP'I, and between the outside of the hulls by "BWH". ~.
The barge SSB is elongated whereby the ratio of "BLH" to "BWH" is at least 2,5 to 1 and preferably larger; and likewise for the ratio of "BLP" to "BWP".
~2) "CL" is total load of crane means C on the barge (weight of crane with and without load3;

. , ~ . , ~ ;, :

.,, ,: . .

(3) I'TA" and "PA" is the locus of trim axis and pitch axis of the barge SSB:
(4) "LC" is the locus and distance of total crane means load "CLt in relation to barge trim axis TA
at beginning, during and cessation of movement of said crane means C;
(5) "CLM" is the resultant moment about the barge trim axis TA due to crane means load "CL" and its locus "LC" with respect to the barge trim~axis according to (4) above -- "CLM" varying in accord-ance with variation of l'LCI' and/or ''CLI' per (2), (3), and (4) above.

(6) "BCMP" are the righting moments of the barge columns (22 or 120) about the axis TA (or PA) when the barge SSB is in seml-submerged high draft pipe-laying operational condition and counteracting "CLM"
per (5) above; and "BCMP" is the total of such righting moments produced by the effect of the water plane area of each barge column (22 or 120) called "BCA" and the square of the distance of the centroid of each such barge column waterplane area "BCA" from the trim or pitch axis TA or PA, the latter distance being called "BCAL". The aforesaid "BCMP" is determined according to the following:
a) BCMP =[ [BCAx(BCAL) xKl]+K2 ] sin wherein _49_ . . .

.... . .. ... . .. ... : - -1~39~)~ 8 (b) Kl is a constant which is a function of the unde~ater geometry of the barge SSB (10 or 110); and (c) K2 is a constant which is a function of the unde~ater geometry of the barge SSB, the moment of inertia of each l`~
column about the column's own axis "CTA" extending transversely ~ the barge SSB and the we~ght distribution ;-~
within the vessel.
(d~ e is the angle of inclination of barge SSB about the trim axis from the orig-inal equilibrium position (see Fig.14C;
angle ~ is equal to "CMIT" discussed on page 44 above).

(7) If crane induced moment "CLM" per (5) above in typical operation of the crane means C over a frac- , :
tion of the total possible crane means travel longitudinally of the barge SSB is such that CLM
exceeds the value of BCMP for aforesaid angle ~
equaling approximately 0,5 per (6) above, thus ; .
causing an angle of trim of barge SSB due to such crane induced moment "CLM" absent counteracting ballast per paragraph 8, 9, and 10 below (such angle without such correction being called "BATC") to be more than plus or minus about one-half degree change . - . . , .. .. .. .. .. ... .
. , . ; - .. . . . .. .
. - . . . .. . . .

3~3~
in barge trim angle as compared to the preset angle of trim "PAT" before said crane means movement per .
paragraphs (4) and (5) above.

(8) The described ballast means of barge SSB is ~ ~.
cperable in semi-submerged condition to c~ange the angle of trim of said barge about TA and establish "PAT" at a desired angle, generally about 0.0 to 2.5 degrees, and preferably about l.5 degrees, with respect to the horizontal before movement of said crane means C per (3), (4) and (5) above;

(9) The ballast means of barge SSB is operable in semi-submerged condition between beginning and cessation of movement of said crane means per (4), ~
(5), (6), and (7) above to limit the aforesaid angle "BATC" so that change in barge angle of trim "CMIT" defined above and shown in FIGURE 14C
is less than plus or minus about one-half degree variation from the preset barge angle of trim "PAT". 1 (lO) "LCM" represents the limiting extent of longitudinal movement of crane means C and crane load "CL" in relation to barge platform length '~LP"
which is possible without ballasting to counteract "BATC" whereas when '~CM" exceeds such limit said ballast means ~s operated to limit '~ATC" and maintain "C~T" within the limits stated in paragraph (9) above.

; . . , .:, . :

. . .

~ 1~3 ~6 8 (11) The barge SSB has columns (22 or 120) of such height '~BCH" and the means for ballasting the barge SSB is operable ~o raise it to a low draft condition so that the twin hulls (12 or 112) have freeboard and also operable to ballast the vessel to semi- :~
submerged high draft pipelaying condition such that the defined and shown load line draft "LLD" of the barge SSB in relation to height of the barge columns "BCH" is within the limits of envelope curves A and B of FIGURE 13 of this application and preferably is according to curve C of FIGURE 13 of this application.
(12) The minimum waterline above the top surfaces of the hulls when the barge is in high draft semi-submerged column stabilized operating condition is represented by "MWLH" and is preferably equal to or greater than 0,25 the height of the barge columns "BCH" and at least eight feet, (13) The pipeline transition segment PLTS in the column stabilized semi-submerged operational condit-ion of the barge SSB is adjusted about a transversely extending axis in relation to the attitude of the barge about its trim axis and to the horizontal such that the curvature of the pipeline extending from the barge end and over the pipeline transition segment PLTS is controlled so as not to exceed :: . . . . .

~ 035~68 allo~able stresses for the pipeline and its coating;
such adjustment to segment PLTS is made in conjunc-tion with and correlated to operation of the ballast means for maintaining the draft of the barge within the stated limits and also maintaining barge trim angle change "CMIT" less than plus or minus about one-half degree variation from the preset angle of trim PAT whereby the relative angular relation between the barge SSB and pipeline transition segment PLTS is substantially maintained throughout pipelaying operations so as not to exceed allowable stress for the pipeline and/or any coating which is applied to the pipeline.
(14) Additional important features include: (a) hulls having non-streamlined top and bottom surfaces, for example, generally parallel planar top and bottom hull surfaces, extending throughout substantially the entire length of the hulls with each hull preferably having a generally rectangular cross-section with its longer axis extending in the direction of the transverse centerline of the barge, with permissible variations in the configuration of the hull sides as discussed previously9 so as to provide increased mass resistance to movement of the hulls through water in a vertical direction when the barge lies in ,. . .

~ G~3~6 8 high draft column stabilized semi-submerged operating condi~ion; (b) a plurality of longitudinally spaced structural means reinforcing the structural relation-ship of the hulls, pla~forms and columns, with such structural means including substantially transversely extending members structurally interconnecting the .
hulls adjacen~ the uppermost portions of the hulls and restraining the hulls àgainst lateral displacement relative to one another; (c) at least six columns interconnecting the hulls and platform with three col-umns upstanding from each hull and a pair of columns located adjacent each of the bow and stern ends of the barge, although one or more additional pairs of columns may be provided, with four pairs of columns being utilized in each embodiment of the disclosed barge;
(d3 also the area of the columns, the number thereof and the distance of ~he columns from the longitudinal and transverse centerline of the barge are such as to provide a greater righting moment about the pitch axis "BCMP" than the righting moment about the longitudinal roll axis "BCM~" when the barge is in semi-submerged high draft column stabilized operating condition;
'~CMR" is determined similary as above stated ;n paragraph (6) with respect to BCMP except that the distance of the centroid of each barge column water-plane area is measured from the roll axis RA (or heel axis HA) and the constant K2~S substituted for the constant ~ n the formula stated in paragraph 6(a) ,, . , , . . :

lV3~68 above wllerein K2 s a constant which ls a function of the underwater geometry of the barge, the moment of inertia aE each column about the column's own axis extending longitudinally parallel to the longitudinal axis of the barge and the weight distribution within the barge; and (e) each column should be constant in cross-sectional area at least for the intermediate portion of the column which extends vertically from a point located 0.25 of the total column height above the hulls to a point located 0,75 of the total column height above the hulls (0,25 of the total column height below the platform~.
It is noted that barge lO and llO include above discussed means for ballasting to change the at~itude of the barge about its roll axis RA when that should be necessary or desirable.
It is noted that in prior column-stabilized twin hull semisubmersible derrick barges used for pipelaying utilizing the vessel arrangements disclosed in assignee's aforementioned U, S. Patents No. 3,835,800, No, 3,685,305 and No. 3,704,596 (as discussed earlier in this application) all crane load during pipe laying operation is transferred to the vessel hulls adj acent the stern at the same locus; hence, there are no comparable conditions in ~such prior pipelaying vessels as changing "LC" of crane load 1'CL", per above par (4) .. - ,. . . .
:

l~P3~

or change in "CL~f" per above par (4), or changing "CLM" in relation to '~CMP" and counteraction of ballast for adjustment of '~ATC" to maintain "CMIT" per above paragraph (5) through

(10). [Said paragraphs being on pages 49-51 of this specification.]
CLAIM TERM DEFINITIONS: The following designations are used in the claims hereafter in the same way as they are in above paragraphs numbered (1) through (13) above with reference to the drawings [as stated in the paragraph preceding said numbered paragraphs (1) through (13)]:
_ ____ _ _ ~
(1) through (13)]:
(a) "BLP" and '~LH" and '~WP" and "B~H" are defined in said numbered paragraph 1. .
(b) "CL" and "C" are defined in said numbered paragraph 2.
(c) "TA" is defined in said numbered paragraph 3, (d) "LC" is defined in said numbered paragraph 4. :
(e) "CLM" is defined in said numbered paragraph 5. -~
(f) "BCMP" and '~CA" and "CTA" and angle ~ are defined in said numbered paragraph 6.
(g) "BATC" and "PAT" and "CMIT" are defined in said numbered paragraphs 7 and 9 and also in paragraph 10 which defines "LCMn.
(h) "BCH" is the height of the barge's columns.
(i) "LLD" is the load line draft which is set forth in F~GURE 13 in relation to column height and -~ :
shown in FIGURE 14A. ~ ~
.,',, "' '., ~....... . .
. . - : -' .. ~ ~ , ' ' ., . . ... . . . , . ;

39~:~6~
(J) "PAT" is ~he barge's preset angle of trim per paragraphs 7 and 8 above and is provided by selective ballasting and/or deballasting the fore and aft ballast compartments as described, above .
The invention may be embodied in other spécific forms without departing from the spir~t or essen~ial characteristics thereof. The present embod~ments are therefore to be con-sidered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes ~hich come within the meaning and range of equivalency of the claims are therefore to be embraced therein.

~A

Claims (93)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A column stabilized semi-submersible pipelaying barge and pipeline transition combination comprising:
a pair of elongated hulls disposed in spaced side by side relation with each hull having substantially parallel substantially planar top and bottom surfaces disposed substantially horizontal and perpendicular to a vertical plane through the longitudinal centerline of the barge and extending substantially the length of each hull, with the transverse horizontal dimension of each hull being greater than its vertical dimension;
a working platform spaced above said hulls a pre-determined height;
means for supporting said platform in fixed spaced relation above said hulls including at least three columns connecting with each of said hulls and said platform and located at spaced intervals along said hulls;
the distance between the extremities of said barge along the barge's longitudinal centerline being substantially greater than the distance between the extremities of said barge along the barge's transverse centerline, with the ratio of "BLH" to "BWH" being at least 2.5 to 1 and the ratio of "BLP" to "BWP" being at least 2.5 to 1 at least one column on each hull being located adjacent the stern end of said barge, another of said columns on each hull being located adjacent the opposite end of the barge, with at least one additional column at an intermediate position on each hull;

a plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns;
said hulls having ballast compartments and said barge including means for ballasting the barge to alter its draft between a low draft hull supported floating condition with the hulls having freeboard and a high draft semi-submerged column stabilized floating pipelaying operating condition;
each of said columns having a height "BCH" and a pre-determined cross-sectional area "BCA", with each column's cross-sectional area "BCA" being the same for at least that part of the column length extending between about 0.25 "BCH"
above hull top to about 0.75 "BCH" above hull top;
the area of said columns, the number thereof and the distance of said columns from the barge's longitudinal roll axis and transverse pitch axis being such as to provide a greater righting moment about the transverse pitch axis than the righting moment about the longitudinal roll axis when said barge is in semi-submerged high draft pipelaying operating condition;
means for supporting and paying out pipeline from one end of said barge including pipeline transition means for supporting a pipeline extending from said barge end into the water;
means including said pipeline transition means for controlling the curvature of a segment of the pipeline extend-ing from said barge end and over said pipeline transition means;

crane means carried by said barge with means for moving said crane means substantially longitudinally of the barge along most of said platform length "BLP" from near the aforesaid barge end to near the opposite barge end; said crane means including means for lifting transferring and setting loads and being of a size, weight and capacity such that total crane means load "CL" and its locus "LC" in rela-tion to barge trim axis TA at beginning, during and cessation of movement of said crane means cause resultant moment "CLM"
about the barge trim axis TA of such magnitude whereby typical operation of said crane means over a substantial portion of said "BLP" will cause a change in the angle "BATC" due to movement of said crane means whereby "BATC" will exceed plus or minus about one-half degree from the preset angle of trim of the barge "PAT" before such movement of said crane means if said moment "CLM" is not counteracted;
said ballast means being operable to preset said barge trim angle "PAT" between predetermined angular limits;
said ballast means also being operable between beginning and cessation of movement of said crane means as above stated to maintain the barge angle of trim change "CMIT"
less than plus or minus one-half degree variation from said preset barge trim angle "PAT";
said barge having columns of such height "BCH" and said means for ballasting the vessel in semi-submerged condition being operable so that the load line draft of the barge "LLD" in relation to barge column height "BCH" is with-in the limits of envelope curves A and B of FIGURE 13 of this application.

2. A pipe layer combination according to claim 1, wherein said ballasting means are operative to provide a load line draft "LLD" of the semi-submerged barge in relation to barge column height "BCH" according to curve C of FIGURE 13 of this application.

3. A pipe layer combination according to claim 1 wherein said ballast means establishes a preset barge trim angle "PAT" of between about 0.0 to 2.5 degrees from horizontal and bow up.

4. A pipe layer combination according to claim 1 including means for establishing the angle of the pipeline transition means relative to horizontal and in relation to the draft of the barge and angular attitude of the barge about its trim axis so as to maintain curvature of the pipeline extending from said barge end and over said pipeline transit-ion section so as not to exceed allowable stress for the pipeline and any coating on the pipeline.

5. A pipe layer combination according to claim 4 wherein said last-mentioned means is operative in conjunction with said means for maintaining barge angle of trim change "CMIT" less than plus or minus one-half degree variation from the barge's preset angle of trim "PAT" due to longitud-inal movement of said crane means.

6. A pipe layer combination according to claim 1 wherein said crane means has sufficient capacity and a boom rotatable about a substantially vertical axis and of suffic-ient outreach for lifting operations off at least one side of said barge and off at least said first-mentioned end of the barge when said crane is longitudinally located adjacent said barge end from which pipeline is paid out over said pipeline transition means.

7. A pipe layer combination according to claim 6 wherein said crane means has sufficient capacity and said boom sufficient outreach for lifting operations off said second-mentioned opposite end of said barge when said crane is located longitudinally adjacent said opposite barge end.

8. A pipe layer combination according to claim 1 wherein said crane means comprises a gantry crane.

9. A pipe layer combination according to claim 8 wherein said crane mounting means includes a pair of tracks transversely spaced one from the other and extending longitud-inally along said platform a distance at least three-quarters of the barge length, said gantry crane having sufficient capa-city and including a boom rotatable about a substantially vertical axis and of sufficient outreach for lifting operat-ions off at least one side of said barge and off at least said first-mentioned end of said barge when said crane is located along said tracks longitudinally adjacent said first-mentioned barge end.

10. A barge according to claim 9 wherein said crane has sufficient capacity and said boom sufficient outreach for lifting operations off said second-mentioned opposite end of said barge when said crane is located along said tracks longi-tudinally adjacent said opposite barge end.

11. A pipe layer combination according to claim 1 wherein the magnitude of barge "BLP" and "BLH" and of result-ant moment "CLM" due to movement of said crane means and load "CL" longitudinally along said barge platform a distance in excess of one-quarter of the barge platform length "BLP" are such as to cause a change in the angle "BATC" exceeding plus or minus one-half degree as compared to the preset barge angle of trim "PAT" if such resultant CLM is not counteracted; said ballast means being operative between beginning and cessation of such longitudinal movement of said crane means to maintain said "CMIT" less than plus or minus one-half degree variation from said "PAT".

12. A pipe layer combination according to claim 1 wherein said crane means comprises a crawler type crane.

13. A pipe layer combination according to claim 1 said means for supporting and paying out pipeline extends longitudinally along said platform along one side of said barge.

14. A pipe layer combination according to claim 1 wherein said crane means is mounted for longitudinal movement along the opposite side of said barge.

15. A pipe layer combination according to claim 1 wherein said means for supporting and paying out of pipeline extends longitudinally along said platform substantially along the centerline of said barge.

16. A pipe layer combination according to claim 15 wherein said crane means is mounted for longitudinal movement along one side of said barge and along one side of said pipeline support means.

17. A pipe layer combination according to claim 16 further comprising: second crane means carried by said barge with means mounting said second crane means for movement sub-stantially longitudinally of the barge along said platform;
said second crane means including means for lifting, trans-ferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said second crane means along the barge platform a predetermined distance for crane means operation when said barge is in said high draft semi-submerged pipelaying condition will cause change in angle "BATC" exceeding plus or minus about one-half degree as compared to the preset barge angle of trim "PAT" prior to such longitudinal movement of said second crane means absent suffic-ient counter-correction of said "BATC"; said second crane means being mounted for longitudinal movement along the opposite side of said barge and along the opposite side of said pipe-line support means; said ballast means for counter-acting angle change "BATC" caused by movement of said first and/or second crane means longitudinally along said platform being operable during such crane movement to maintain angle "CMIT"
less than plus or minus about one-half degree variation from preset barge angle of trim "PAT" prior to such longitudinal crane movement.

18. A pipe layer combination with a barge according to claim 1 wherein the cross section of each said barge hull is generally rectangular for substantially the entire length of each hull, with the longer axis of each rectangular hull cross section extending in like direction as the transverse centerline of the barge.

19. A pipe layer combination with a barge according to claim 1 wherein said plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns includes substantially trans-versely extending members structurally interconnecting the hulls adjacent the uppermost portions of the hulls and restrain-ing the hulls against lateral displacement relative to one another.

20. A pipe layer combination with a barge according to claim 1 wherein at least one of the columns on each said hull has a cross section with a dimension extending in the direct-ion of the longitudinal barge axis greater than the column's transversely extending dimension, with the centroid of the cross section of at least one column on each hull lying out-board of the longitudinal centerline of the associated hull.

21. A column stabilized semi-submersible vessel comprising:
a pair of elongated hulls disposed in spaced side-by-side relation with each hull having substantially parallel substantially planar top and bottom surfaces disposed sub-stantially horizontal and perpendicular to a vertical plane through the longitudinal centerline of the vessel and extending substantially the length of each hull, with the transverse horizontal dimension of each hull being greater than its vertical dimension;
a working platform spaced above said hulls a predeter-mined height;
means for supporting said platform in fixed spaced relation above said hulls including at least three columns connecting with each of said hulls and said platform and located at spaced intervals along said hulls;
the distance between the extremities of said vessel along the vessel's longitudinal centerline being substantially greater than the distance between the extremities of said vessel along the vessel's transverse centerline, with the ratio of "BLH" to "BWH" being at least 2.5 to 1 and the ratio of "BLP" to "BWP" being at least 2.5 to 1;

at least one column on each hull being located adjacent one end of said vessel, another of said columns on each hull being located adjacent the opposite end of the vessel, with at least one additional column at an intermediate position on each hull;
a plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns;

said hulls having ballast compartments and said vessel including means for ballasting the vessel to alter its draft between a low draft hull supported floating condition with the hulls having freeboard and a high draft semi-submerged column stabilized floating and operating condition;
each of said vessel columns having a height "BCH"
and a predetermined cross-sectional area "BCA", with each column's cross-sectional area "BCA" being the same for at least that part of the column length extending between about 0.25 "BCH" above hull top to about 0.75 "BCH" above hull top;
the area of said columns, the number thereof and the distance of said columns from the vessel's longitudinal roll axis and transverse pitch axis being such as to provide a greater righting moment about the transverse pitch axis than the righting moment about the longitudinal roll axis when said vessel is in semi-submerged high draft floating and operating condition;
crane means carried by said vessel with means for moving said crane means substantially longitudinally of the vessel along most of said platform length "BLP" from near one end of said vessel to near the opposite vessel end; said crane means including means for lifting, transferring and setting loads and being of a size, weight and capacity such that total crane means load "CL" and its locus "LC" in relation to the vessel's trim axis TA at beginning, during and cessation of movement of said crane means cause resultant moment "CLM" about the barge trim axis TA of such magnitude whereby typical operation of said crane means over a substant-ial portion of said "BLP" will cause a change in the angle "BATC" due to movement of said crane means whereby "BATC" will exceed plus or minus about one-half degree from the preset vessel angle of trim "PAT" before such movement of said crane means if said moment "CLM" is not counteracted;
said ballast means being operative to preset said vessel trim angle "PAT" between predetermined angular limits;
said ballast means also being operative between beginning and cessation of movement of said crane means as above stated to maintain the vessel's angle of trim change "CMIT" less than plus or minus one-half degree variation from said preset vessel trim angle "PAT";
said vessel having columns of such height "BCH"
and said means for ballasting the vessel in semi-submerged condition being operable so that the vessel's load line draft "LLD" in relation to vessel column height "BCH" is within the limits of envelope curves A and B of FIGURE 13 of this application.

22. A vessel according to claim 21, wherein said ballasting means are operative to provide a load line draft "LLD" of the semi-submerged vessel in relation to barge column height "BCH" according to curve C of FIGURE 13 of this applic-ation.

23. A vessel according to claim 21 wherein said ballast means establishes a preset vessel trim angle "PAT" of between about 0.0 to 2.5 degrees from horizontal and bow up.

24. A pipe layer combination including a column stabilized semi-submersible vessel according to claim 21 and further comprising:
means for supporting and paying out pipeline from one end of said vessel including pipeline transition means for supporting a pipeline extending from said vessel end into the water;
means including said pipeline transition means for controlling the curvature of a segment of the pipeline extend-ing from said vessel end and over said pipeline transition means; and means for establishing the angle of the pipeline transition means relative to horizontal and in relation to the draft of the vessel and angular attitude of the vessel about its trim axis so as to maintain curvature of the pipeline extending from said vessel end and over said pipeline transition means so as not to exceed allowable stress for the pipeline and any coating on the pipeline.

25. A pipe layer combination according to claim 24 wherein said last-mentioned means is operative in conjunction with said means for maintaining the vessel's angle of trim change "CMIT" less than plus or minus about one-half degree variation from the vessel's preset angle of trim "PAT" due to longitudinal movement of said crane means.

26. A vessel according to claim 21 wherein said crane means has sufficient capacity and a boom rotatable about a substantially vertical axis and of sufficient outreach for lifting operations off at least one side of said vessel and off at least said first-mentioned end of the vessel when said crane is longitudinally located adjacent said vessel end.

27. A vessel according to claim 26 wherein said crane means has sufficient capacity and said boom sufficient out-reach for lifting operations off said second-mentioned opposite end of said vessel when said crane is located longitudinally adjacent said opposite vessel end.

28. A vessel according to claim 21 wherein said crane means comprises a gantry crane.

29. A vessel according to claim 28 wherein said crane mounting means including a pair of tracks transversely spaced one from the other and extending longitudinally along said platform a distance at least three-quarters of the vessel length "BLP", said gantry crane having sufficient capacity and including a boom rotatable about a substantially vertical axis and of sufficient outreach for lifting operations off at least one side of said vessel and off at least said first-mentioned end of said vessel when said crane is located along said tracks longitudinally adjacent said first-mentioned vessel end.

30. A vessel according to claim 29 wherein said crane has sufficient capacity and said boom sufficient outreach for lifting operations off said second-mentioned opposite end of said vessel when said crane is located along said tracks longi-tudinally adjacent said opposite vessel end.

31. A vessel according to claim 21 wherein:
the magnitude of barge "BLP" and "BLH" and of moment "CLM" due to movement of said crane means and load "CL" longi-tudinally along said vessel platform a distance in excess of one-quarter of the vessel platform length "BLP" are such as to cause a change in angle "BATC" exceeding plus or minus about one-half degree as compared to the preset vessel angle of trim "PAT" if such resultant "CLM" is not counteracted; said ballast means being operative between beginning and cessation of such longitudinal movement of said crane means to maintain angle "CMIT" less than plus or minus one-half degree variation from said "PAT".

32. A pipe layer combination according to claim 21 wherein said crane means comprises a crawler type crane.

33. A pipe laying system according to claim 24 wherein said means for supporting and paying out pipeline extends longitudinally along said platform along one side of said vessel.

34. A pipe laying system according to claim 24 wherein said means for supporting and paying out of pipeline extends longitudinally along said platform substantially along the centerline of said vessel; said crane means being mounted for longitudinal movement along one side of said vessel and along one side of said pipeline support means.

35. A pipe laying system according to claim 34 further comprising: second crane means carried by said vessel with means mounting said second crane means for movement substanti-ally longitudinally of the vessel along said platform; said second crane means including means for lifting, transferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said second crane means along the vessel platform a predetermined distance for crane means oper-ation when said vessel is in said high draft semi-submerged pipelaying condition will cause change in the angle "BATC"
exceeding plus or minus about one-half degree as compared to the preset barge angle of trim "PAT" prior to such longitudinal movement of said second crane means absent sufficient counter-correction of said "BATC"; said second crane means being mounted for longitudinal movement along the opposite side of said vessel and along the opposite side of said pipeline support means; said ballast means for counteracting said angle change "BATC" caused by movement of said first and/or second crane means longitudinally along said platform being operable during such crane movement to maintain angle "CMIT" less than plus or minus about one-half degree variation from the vessel's preset angle of trim "PAT" prior to such longitudinal crane movement.

36. A vessel according to claim 21 wherein the cross section of each said hull is generally rectangular for sub-stantially the entire length of each hull, with the longer axis of each rectangular hull cross section extending in like direction as the transverse centerline of the vessel.

37. A vessel according to claim 21 wherein said plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns includes substantially transversely extending members structur-ally interconnecting the hulls adjacent the uppermost portions of the hulls and restraining the hulls against lateral displace-ment relative to one another.

38. A column stabilized semi-submersible vessel comprising:
a pair of elongated hulls disposed in spaced side by side relation with each hull having substantially parallel substantially planar top and bottom surfaces disposed substant-ially horizontal and perpendicular to a vertical plane through the longitudinal centerline of the vessel and extending sub-stantially the length of each hull, with the transverse horizontal dimension of each hull being greater than its vertical dimension;
a working platform spaced above said hulls a predeter-mined height;
means for supporting said platform in fixed spaced relation above said hulls including at least three columns connecting with each of said hulls and said platform and located at spaced intervals along said hulls;
the distance between the extremities of said vessel along the vessel's longitudinal centerline being substantially greater than the distance between the extremities of said vessel along the vessel's transverse centerline, with the ratio of "BLH" to "BWH" being at least 2.5 to 1 and the ratio of "BLP" to "BWP" being at least 2.5 to 1;
at least one column on each hull being located adjacent one end of said vessel, another of said columns on each hull being located adjacent the opposite end of the vessel with at least one additional column at an intermediate position on each hull;
a plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns;
said hulls having ballast compartments and said vessel including means for ballasting the vessel to alter its draft between a low draft hull supported floating condition with the hulls having freeboard and a high draft semi-submer-ged column stabilized floating and operating condition, each of said vessel columns having a height "BCH" and a predetermined cross-sectional area "BCA", with each columns cross-sectional area "BCA" being the same for at least that part of the column length extending between about 0.25 "BCH"
above hull top to about 0.75 "BCH" above hull top;

the area of said columns, the number thereof and the distance of said columns from the vessel's longitudinal roll axis and transverse pitch axis being such as to provide a greater righting moment about the transverse pitch axis than the righting moment about the longitudinal roll axis when said vessel is in semi-submerged high draft floating and operating condition;
crane means carried by said vessel with means for moving said crane means substantially longitudinally of the vessel along most of said platform length "BLP" from near one end of said vessel to near the opposite vessel end; said crane means including means for lifting, transferring and setting loads and being of a size, weight and capacity such that total crane means load "CL" and its locus "LC" in relation to the vessel's trim axis TA at beginning, during and cessation of movement of said crane means cause resultant moment "CLM" about the barge trim axis TA of such magnitude whereby typical operation of said crane means over a substant-ial portion of said "BLP" will cause a change in the angle "BATC" due to movement of said crane means whereby "BATC" will exceed plus or minus about one-half degree from the preset vessel angle of trim "PAT" before such movement of said crane means if said moment "CLM" is not counteracted;
said ballast means being operative to preset said vessel trim angle "PAT" between predetermined angular limits;

said ballast means also being operative between beginning and cessation of movement of said crane means as above stated to maintain the vessel's angle of trim change "CMIT" less than plus or minus one-half degree variation from said preset vessel trim angle "PAT".

39. A vessel according to claim 38 wherein said vessel has columns of such height "BCH" and said means for ballasting the vessel in semi-submerged condition are operable so that the vessel's load line draft "LLD" in relation to vessel column height "BCH" is within the limits of envelope curves A and B
of FIGURE 13 of this application.

40. A vessel according to claim 38 wherein said ballast means establishes a preset vessel trim angle "PAT" of between about 0,0 to 2.5 degrees from horizontal and bow up.

41. A column stabilized semisubmersible pipelaying barge and pipeline transition combination comprising:
a pair of elongated hulls disposed in spaced side-by-side relation;
a working platform spaced above said hulls a predeter-mined height;
means for supporting said platform in spaced relation above said hulls including columns connected to said hulls and said platform;
the distance between the extremities of said barge along the longitudinal centerline of said barge being substantially greater than the distance between the extremities of said barge along the transverse centerline thereof;
said hulls having ballast compartments for ballasting said barge to alter its draft between a low draft hull supported floating condition and a high draft semisubmerged column stabilized and pipelaying operating condition;
said columns having predetermined cross-sectional areas and being located on the hulls to provide righting moments about the pitch and roll axes of said barge when in said high draft semi-submerged condition;
the area of said columns, the number thereof, and the distance of the columns from the longitudinal and transverse centerlines of the barge being such as to provide a greater righting moment about the transverse pitch axis than the righting moment about the longitudinal roll axis when the barge is in high draft semisubmerged pipelaying operating condition;
means for supporting and paying out pipeline from one end of said barge including a pipeline transition means for supporting the pipeline extending from said barge end into the water;
means including said pipeline transition means for controlling the curvature of a segment of the pipeline extend-ing from said barge end and over said pipeline transition means;
crane means carried by said barge with means mounting said crane means for movement substantially longitudinally of the barge along said platform; said crane means including means for lifting, transferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said crane means along the barge platform a predetermined distance when said barge is in said high draft semisubmerged pipelaying condition will cause change in the angle of trim of the barge exceeding about plus or minus one-half degree as com-pared to the barge angle of trim prior to such longitudinal movement of the crane means absent sufficient counter-correc-tion of such change in barge trim angle caused by such move-ment of said crane means;
ballast means for counteracting the change in angle of trim of the barge caused by movement of said crane means longitudinally along said platform to maintain the angle of trim of said barge within an angle of change about the trim axis so that the curvature of the pipeline extending from said barge end and over said pipeline transition section does not exceed allowable stress for the pipeline and any coating on the pipeline.

42. A pipe layer combination according to claim 41 wherein said barge ballast means includes means for providing preset barge angle of trim for pipelaying operations.

43. A pipe layer combination according to claim 42 wherein the last mentioned ballast means is operative to provide a preset bow-up trim angle "PAT" between 0 to 2.5 degrees from horizontal and to maintain angle "CMIT" within one-half degree.

44. A pipe layer combination according to claim 41 including means for establishing the angle of the pipeline transition means relative to horizontal and the attitude of the barge about its trim axis so as to maintain curvature of the pipeline extending from said barge end and over said pipeline transition section so as not to exceed allowable stress for the pipeline and any coating on the pipeline.

45. A pipe layer combination according to claim 44 wherein said last-mentioned means is operative in conjunction with said means for maintaining said barge angle of trim "CMIT"
within an angle of change about the trim axis of one-half degree from such angle of barge trim existing prior to longitu-dinal movement of said crane means.

46. A pipe layer combination according to claim 41 wherein said crane means has sufficient capacity and a boom rotatable about a substantially vertical axis and of sufficient outreach for lifting operations off at least one side of said barge and off at least the aforesaid end of said barge when said crane is longitudinally located adjacent said barge end.

47. A pipe layer combination according to claim 46 wherein said crane means has sufficient capacity and said boom sufficient outreach for lifting operations off the opposite end of said barge when said crane is located longitudinally adjacent said opposite barge end.

48. A pipe layer combination according to claim 41 wherein said crane means comprises a gantry crane.

49. A pipe layer combination according to claim 48 wherein said crane mounting means includes a pair of tracks transversely spaced one from the other and extending longitud-inally along said platform a distance at least three-quarters of the barge length, said gantry crane having sufficient capacity and including a boom rotatable about a substantially vertical axis and of sufficient outreach for lifting operations off at least one side of said barge and off at least the aforesaid end of said barge when said crane is located along said tracks longitudinally adjacent said barge end.

50. A barge according to claim 49 wherein said crane has sufficient capacity and said boom sufficient outreach for lifting operations off the opposite end of said barge when said crane is located along said tracks longitudinally adjacent said opposite barge end.

51. A pipelaying system according to claim 41 wherein; the weight and location of said crane means and the resultant moment "CLM" about the barge's trim axis TA being such that movement of said crane means longitudinally along said barge platform a distance in excess of one-quarter of the barge length causes a change in the angle "BATC" exceeding plus or minus one-half degree as compared to the barge angle of trim PAT prior to such longitudinal movement of said crane means; if such moment CLM is not counteracted to maintain barge trim angle "CMIT" within plus or minus one-half degree from preset angle "PAT".

52. A pipe laying apparatus according to claim 51, wherein said ballast means for counteracting the change in angle of trim of the barge caused by movement of said crane means longitudinally along said platform is operable during such movement of the crane to maintain the change in said barge angle of trim "CMIT" less than plus or minus one-half degree variation from such angle of trim existing prior to longitudinal movement of said crane means.

53. A pipe layer combination according to claim 41 wherein said crane means comprises a crawler type crane.

54. A pipe laying system according to claim 41 wherein said means for supporting and paying out pipeline extends longitudinally along said platform along one side of said barge,

55. A pipe laying system according to claim 54 wherein said crane means is mounted for longitudinal movement along the opposite side of said barge.

56. A pipe laying system according to claim 41 wherein said means for supporting and paying out pipeline extends longitudinally along said platform substantially along the centerline of said barge.

57. A pipe laying system according to claim 56 wherein said crane means is mounted for longitudinal movement along one side of said barge and along one side of said pipe-line support means.

58. A pipe laying system according to claim 57 further comprising a second crane means carried by said barge with means mounting said second crane means for movement substanti-ally longitudinally of the barge along said platform; said second crane means including means for lifting, transferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said second crane means along the barge platform a predetermined distance for crane means operation when said barge is in said high draft semi-submerged pipelaying condition will cause change in the angle of trim of the barge exceeding about plus or minus one-half degree as compared to the barge angle of trim prior to such longitudinal movement of said second crane means absent sufficient counter-correction of barge trim angle; said second crane means being mounted for longitudinal movement along the opposite side of said barge and along the opposite side of said pipeline support means; said ballast means for counter-acting the change in angle of trim of the barge caused by movement of said first and/or second crane means longitudinally along said platform being operable during such crane movement to maintain the change in angle of trim of said barge about the trim axis less than plus or minus one-half degree variat-ion from such angle of trim existing prior to such longitudinal crane movement.

59. A pipe laying system according to claim 41 wherein the cross section of each said barge hull is generally rectangular for substantially the entire length of each hull, with the longer axis of each hull cross section extending in a direction of the transverse centerline of the barge so as to provide increased mass resistance to movement of said hulls through water in vertical direction when said barge is in said high draft semisubmerged column stabilized condition;
said barge also comprising a plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns, said structural means includ-ing substantially transversely extending members structurally interconnecting the hulls adjacent the uppermost portions of the hulls and restraining the hulls against lateral displace-ment relative to one another.

60. A pipe laying system with a barge according to claim 41 wherein at least one of the columns on each said hull has a cross section with a dimension extending in the direction of the longitudinal barge axis greater than the column's trans-versely extending dimension, with the centroid of the cross section of at least one column on each hull lying outboard of the longitudinal centerline of the associated hull.

61. A pipe laying system according to claim 41 wherein said barge has a length to width ratio of at least 2.5 to 1.

62. A pipe laying system according to claim 41 wherein said barge has columns of such height and means for ballasting the vessel in semi-submerged condition so that the load line draft of the barge in relation to column height of the barge is within the limits of envelope curves A and B
of FIGURE 13 of this application.

63. A pipe laying system including a barge according to claim 62 wherein said ballasting means are operative to provide a load line draft of the semi-submerged barge in relation to column height of the barge according to curve C
of FIGURE 13 of this application.

64. A pipe laying system including a barge according to claim 41 wherein:
the barge is elongated so that the ratio of "BLH" to "BWH" is at least 2.5 to 1 and the ratio of "BLP" to "BWP" is at least 2.5 to 1;
said crane means including means for moving the crane longitudinally along the barge platform over the major part of "BLP";
total crane means load "CL" and is locus "LC" in relation to barge trim axis TA at beginning, during and cessation of movement of said crane means being such that the resultant moment "CLM" about the barge trim axis TA is of such magnitude whereby typical operation of said crane means over a substantial portion of said "BLP" Will cause a change in the angle "BATC" due to movement of said crane means whereby "BATC" will exceed plus or minus about one-half degree from the preset barge angle of trim "PAT" before such movement of said crane means if said moment "CLM" is not counteracted;
said ballast means being operative to preset said barge trim angle "PAT" between predetermined angular limits;
said ballast means also being operative between beginning and cessation of movement of said crane means as above stated to maintain the barge angle of trim change "CMIT"
less than plus or minus about one-half degree variation from said preset barge trim angle "PAT".

65. A pipe laying system including a barge according to claim 64, wherein said ballast means establishes a preset barge trim angle "PAT" of between about 0.0 to 2.5 degrees from horizontal and bow up.

66. A pipe laying system according to claim 64, said barge having columns of such height "BCH" with said means for ballasting the barge in semi-submerged condition being operable so that the barge's load line draft "LLD" in relation to barge column height "BCH" is within the limits of envelope curves A and B of FIGURE 13 of this application.

67. A pipe laying system including a barge according to claim 66 wherein said ballasting means are operative to provide a load line draft "LLD" of the semi-submerged barge in relation to barge column height "BCH" according to curve C
of FIGURE 13 of this application.

68. A barge according to claim 41 including ballast means for providing a predetermined operational barge trim, said crane means having sufficient capacity and a boom rotat-able about a substantially vertical axis and of sufficient outreach for lifting operations off at least one side of said barge and off at least one end of said barge when said crane is located longitudinally adjacent said one barge end, the weight and location of said crane means and the righting moments provided by said columns being relation to one another such that movement of said crane means longitudinally along said platform a distance in excess of one-quarter of the barge length causes a change in the angle of trim of the barge in excess of plus or minus one-half degree as compared to the barge angle of trim prior to such longitudinal movement of said crane means, said pipeline support means extending longitudinally along said platform substantially along the centerline of said barge, said crane means being mounted for longitudinal movement along one side of said barge and to one side of said pipeline support means, a second crane means carried by said barge with means mounting said second crane means for movement substantially longitudinally of the barge along said platform, said second crane means including means for lifting, transferring and setting loads and being of a size weight and capacity such that longitudinal movement of said second crane means along the barge platform a predetermined distance for crane means operation when said barge is in said high draft semisubmerged pipelaying condition will cause change in the angle of trim of the barge in excess of about plus or minus one-half degree as compared to the barge angle of trim prior to such longitudinal movement of said second crane means absent sufficient counter-correction of barge trim angle, said second crane means being mounted for longitudinal move-ment along the opposite side of said barge and along the oppos-ite side of said pipeline support means, the weight and locat-ion of said second crane means, and the righting moments provided by said columns being in relation to one another such that movement of said second crane means longitudinally along said platform a distance in excess of one-quarter of the barge length causes a change in the angle of trim of the barge in excess of plus or minus one-half degree as compared to the barge angle of trim prior to such longitudinal movement of said second crane means, the cross section of each hull being generally rectangular with the longer axis of each hull cross section extending in the direction of the transverse center-line of the barge so as to provide increased mass resistance to movement of said hulls through water in a vertical direction when said barge lies in said high draft semisubmer-ged column stabilized condition, a plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns, said structural means including substantially transversely extending members struct-urally interconnecting the hulls adjacent the uppermost port-ions of the hulls and restraining the hulls against lateral displacement relative to one another, at least one of the columns on each said hull having a cross section with its dimension extending in the direction of the longitudinal barge axis greater than the column's transversely extending dimension the centroid of the cross section of at least one column on each hull lying outboard of the longitudinal centerline of the associated hull, said barge having a length to width ratio of at least 2,5 to 1.

69. A column-stabilized semi-submersible barge comprising:
a pair of elongated hulls disposed in spaced side-by-side relation;
a working platform spaced above said hulls a predeter-mined height;
means for supporting said platform in spaced relation above said hulls including columns connected to said hulls and said platform;
the distance between the extremities of said barge along the longitudinal centerline of said barge being at least 2,5 times greater than the distance between the extremities of said barge along the transverse centerline thereof;

said hulls having ballast compartments for ballasting said barge to alter its draft between a low-draft hull supported floating condition and a high-draft semi-submerged column-stabilized operating condition;
said columns having predetermined cross-sectional areas and being located on the hulls to provide righting moments about the pitch and roll axes of said barge when in said high-draft semi-submerged condition;
the area of said columns, the number thereof, and the distance of the columns from the longitudinal and trans-verse centerlines of the barge being such as to provide a greater righting moment about the transverse pitch axis than the righting moment about the longitudinal roll axis when the barge is in high-draft semi-submerged operating condition;
crane means carried by said barge with means mounting said crane means for movement substantially longitudinally of the barge along said platform; said crane means including means for lifting, transferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said crane means along the barge platform a predetermined distance when said barge is in said high-draft semi-submerged operating condition will cause change in the angle of trim of the barge exceeding about plus or minus one-half degree as compared to the barge angle of trim prior to such longitudinal movement of the crane means absent sufficient counter-correction of such change in barge trim angle caused by such movement of said crane means;
ballast means for counteracting the change in angle of trim of the barge caused by movement of said crane means longitudinally along said platform to maintain the angle of trim of said barge within an angle of change about the trim axis of plus or minus one-half degree from such angle of trim existing prior to longitudinal movement of said crane means.

70. A barge according to Claim 69 wherein said barge ballast means includes means for providing preset barge angle of trim for pipelaying operations.

71. A barge according to Claim 70 wherein the last mentioned ballast means is operative to provide a preset bow-up barge angle of trim between O to 2.5 degrees from horizon-tal.

72, A barge according to Claim 69 wherein said crane means has sufficient capacity and a boom rotatable about a substantially vertical axis and of sufficient outreach for lifting operations off at least one side of said barge and off one end of said barge when said crane is longitudinally located adjacent said one barge end.

73. A barge according to Claim 72 wherein said crane means has sufficient capacity and said boom sufficient out-reach for lifting operations off the opposite end of said barge when said crane is located longitudinally adjacent said opposite barge end.

74. A barge according to Claim 69 wherein said crane means comprises a gantry crane.

75. A barge according to Claim 74 wherein said crane mounting means includes a pair of tracks transversely spaced one from the other and extending longitudinally along said platform a distance at least three-quarters of the barge length, said gantry crane having sufficient capacity and induding a boom rotatable about a substantially vertical axis and of sufficient outreach for lifting operations off at least one side of said barge and off one end of said barge when said crane is located along said tracks longitudinally adjacent said one barge end.

76. A barge according to Claim 75 wherein said crane has sufficient capacity and said boom sufficient outreach for lifting operations off the opposite end of said barge when said crane is located along said tracks longitudinally adjacent said opposite barge end.

77. A barge according to Claim 69 wherein the weight and location of said crane means and the resultant moment there of about the barge's trim axis as compared to the resultant righting moments provided by said columns are of such magnitude in relation to one another that movement of said crane means longitudinally along said platform a distance in excess of one-quarter of the barge length causes a change in the angle of trim of the barge exceeding plus or minus one-half degree as compared to the barge angle of trim prior to such longitud-inal movement of said crane means.

78. A barge according to Claim 77 wherein said ballast means for counteracting the change in angle of trim of the barge caused by movement of said crane means longitud-inally along said platform is operable during such movement of the crane to maintain the change in angle of trim of said barge about the trim axis less than plus or minus one-half degree variation from such angle of trim existing prior to longitudinal movement of said crane means.

79. A barge according to Claim 69 wherein said crane means comprises a crawler type crane.

80. A pipe laying barge according to Claim 69 further comprising means on said barge for supporting and paying out pipeline from the barge stern, said means extending longitudinally along said platform along one side of said barge

81. A pipe laying barge according to Claim 80 wherein said crane means is mounted for longitudinal movement along the opposite side of said barge.

82. A pipelaying barge according to Claim 69 further comprising means for supporting and paying out pipe-line such means extending longitudinally along said platform substantially along the centerline of said barge.

83. A pipe laying barge according to Claim 82 wherein said crane means is mounted for longitudinal movement along one side of said barge and along one side of said - 92.

pipeline support means.

84. A pipe laying barge according to Claim 83 further comprising a second crane means carried by said barge with means mounting said second crane means for movement substantially longitudinally of the barge along said platform;
said second crane means including means for lifting, trans-ferring and setting loads and being of a size, weight and capacity such that longitudinal movement of said second crane means along the barge platform a predetermined distance for crane means operation when said barge is in said high-draft semi-submerged pipe laying condition will cause change in the angle of trim of the barge exceeding about plus or minus one-half degree as compared to the barge angle of trim prior to such longitudinal movement of said second crane means absent sufficient counter-correction of barge trim angle; said second crane means being mounted for longitudinal movement along the opposite side of said barge and along the opposite side of said pipeline support means; said ballast means for counter-acting the change in angle of trim of the barge caused by movement of said first and/or second crane means longitudinally along said platform being operable during such crane movement to maintain the change in angle of trim of said barge about the trim axis less than plus or minus one-half degree varia-tion from such angle of trim existing prior to such longitud-inal crane movement.

85. A barge according to Claim 69 wherein the cross section of each said barge hull is generally rectangular for substantially the entire length of each hull, with the longer axis of each hull cross section extending in 8 direction of the transverse centerline of the barge so as to provide increased mass resistance to movement of said hulls through water in vertical direction when said barge is in said high-draft semi-submerged column-stabilized condition; said barge also comprising a plurality of longitudinally spaced structural means reinforcing the structural relationship of the hulls, platform and columns, said structural means including substant-ially transversely extending members structurally interconnect-ing the hulls adjacent the uppermost portions of the hulls and restraining the hulls against lateral displacement relative to one another.

86. A barge according to Claim 69 wherein at least one of the columns on each said hull has a cross section with a dimension extending in the direction of the longitudinal barge axis greater than the column's transversely extending dimension, with the centroid of the cross section of at least one column on each hull lying outboard of the longitudinal centerline of the associated hull.

87. A barge according to Claim 69 wherein said barge has a length to width ratio of at least about 4 to 1.

88. A pipe laying system according to Claim 80 with said barge having columns of such height and means for ballast-ing the vessel in semi-submerged condition so that the load line draft of the barge during pipe laying operation in relation to column height of the barge is within the limits of envelope curves A and B of FIGURE 13 of this application.

89. A pipe laying system including a barge according to Claim 88 wherein said ballasting means are operative to provide a load line draft of the semi-submerged barge in relation to column height of the barge according to curve C
of FIGURE 13 of this application.

90. A barge according to Claim 69 wherein:
the brage is elongated so that the ratio of "BLH"
to "BWH" is at least 2,5 to 1 and the ratio of "BLP" to "BWP"
is at least 2.5 to 1;
said crane means including means for moving the crane longitudinally along the barge platform over the major part of "BLP";
total crane means load "CL" and its locus "LC" in relation to barge trim axis TA at beginning, during and cessation of movement of said crane means being such that the resultant moment "CLM" about the barge trim axis TA is of such magnitude whereby typical operation of said crane means over a substantial portion of said "BLP" will cause a change in the angle "BATC" due to movement of said crane means whereby "BATC"
will exceed plus or minus about one-half degree from the preset barge angle of trim "PAT" before such movement of said crane means if said moment "CLM" is not counteracted;
said ballast means being operative to preset said barge trim angle "PAT" between predetermined angular limits;
said ballast means also being operative between beginning and cessation of movement of said crane means as above stated to maintain the barge angle of trim change "CMIT"
less than plus or minus about one-half degree variation from said preset barge trim angle "PAT".

91. A barge according to Claim 90 wherein said ballast means establishes a preset barge trim angle "PAT" of between about 0.0 and 2.5 degrees from horizontal and bow up.

92. A barge according to Claim 90 wherein said barge has columns of such height "BCH" with said means for ballasting the barge in semi-submerged condition being operable so that the barge's load line draft "LLD" in relation to barge column height "BCH" is within the limits of envelope curves A and B
of FIGURE 13 of this application.

93. A barge according to Claim 92 wherein said ballasting means are operative to provide a load line draft "LLD" of the semi-submerged barge in relation to barge column height "BCH" according to curve C of FIGURE 13 of this application.