US3323478A

US3323478A - Floating support

Info

Publication number: US3323478A
Application number: US488378A
Authority: US
Inventors: William A Hunsucker
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-09-20
Filing date: 1965-09-20
Publication date: 1967-06-06
Anticipated expiration: 1984-06-06

Description

w. A. HUNSUCKEF; 3,323,478 I June 6, 1967 FLOATING SUPPORT 2 Sheets-Sheet 1 Filed Sept. 20, 1965 EZ%J. i+2

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United States Patent 3,323,478 FLOATING SUPPORT William A. Hunsucker, 3741 Prestwick Drive, Los Angeles, Calif. 90027 Filed Sept. 20, 1965, Ser. No. 488,378 4 Claims. (Cl. 114.5)

This invention relates to apparatus for supporting heavy loads in or over a body of water, and is particularly directed to improvements over apparatus of the type shown in my prior Patent No. 2,916,002, granted Dec. 8, 1959, for Marine Hoisting Apparatus. The present invention has particular usefulness as a support for marine drilling, salvage or construction operations. This invention will be described in connection with marine drilling apparatus although this is only by way of illustration.

Present-day marinev drilling devices using a floating vessel require specialized construction of the vessel which is very expensive. Moreover, such specialized floating vessels for drilling operations are often so large and diflicult to transport that they cannot pass through existing canals or waterways, and thus have limited usage.

Among the important objects of the present invention are to provide apparatus to overcome the foregoing diificulties by employing substantially conventional vessels to reduce the cost and to enable them to pass through existing waterways.

Conventional supporting apparatus for well drilling operations commonly employ a single floating vessel which tends to roll in response to wind or wave action. Rolling of the vessel seriously interferes with drilling operations, to the extent that drilling activities must be halted during bad weather. The present invention contemplates the use of two supporting vessels with the result that motion of the drilling platform brought about by rolling action of the vessels is largely eliminated. Another object is to provide a marine support employing conventional vessels with minimum modification so that the vessels can be used for conventional purposes when not required for drilling operations.

Another object is to provide a floating support at minimum cost.

Briefly stated, these and other objects of the invention are achieved by a pair of floating vessels, struts spacing the vessels so that eachrnay roll and pitch independently of the other, a support extending laterally between the vessels, one portion of the support being pivotally carried at a low elevation at or near the center of one of the vessels, and another portion of the support being pendantly suspended from a tower on the other of the vessels, thereby minimizing movement of the support brought about by rolling motion of the vessel.

Referring to the drawings,

FIGURE 1 is a top plan view in diagrammatic form showing a preferred embodiment of the invention.

FIGURE 2 is a sectional end elevation taken substantially on the lines 2-2 as shown in FIGURE 1.

FIGURE 3 is a detail of one of the horizontal strut assemblies taken substantially on the lines 33 as shown in FIGURE 1.

FIGURE 4 is a side elevation of the compression legs of the support bridge or deck taken substantially on the lines 4-4 as shown in FIGURE 2.

FIGURE 5 is a side elevation showing the tower and tension member which carries one end of the support bridge or deck.

FIGURE 6 is a side elevation partly broken away showing the gimbal mounting structure at opposite ends of the tension member.

FIGURE 7 is an enlarged detail showing one of the Patented June 6, 1967 "ice pivot supports for the compression legs of the support bridge or deck.

Referring to the drawings, a pair of floating vessels or barges 10 and 11 are provided. These are of substantially conventional design. The vessels are held in spaced relationship by means of strut assemblies 12 and 13 acting in concert with

diagonal members

14 and 15. The diagonal members prevent longitudinal movement of one vessel with relation to the other. Stru-t assembly 13 may optionally be located at the phantom line position as shown at 13'.

One end of each strut assembly is attached to vessel 11 by means of self-aligning connection 16, and the other end of each strut assembly is connected to vessel 10 by means of a self-aligning and rotating connection 17. These strut assemblies and connections are similar to those disclosed in my prior patent identified above. They serve to space the vessels 10 and 11 apart in predetermined relationship and at the same time penmit each vessel to respond to wind and wave action independently of the other vessel. The strut assemblies 12 and 13 are duplicates. As shown in FIGURE 3, the strut assembly 12 has yoke parts 23 at opposite ends connected by ends 18 and 19 to parallel parts '20 and 21. Plate 22 fixed to vessel 11 is fixed to one pair of the part-s20 and 21, while plate 24 is fixed to the other pair of

parts

20 and 21. The plate 24 is attached to vessel 10 by means of a shank 26 fixed to plate 24 and free to rotate within tubular member 27. A nut 28 vthreaded to the shank 26 has a flange which prevents disassembly. Bearing plates 29 and 30 distribute loads from the plates to the vessel 10.

The support bridge or deck 31 spans the distance between the two vessels It and 11 and is supported in a novel manner upon them. Compression legs 32 on the support bridge 31 extend into wells 33 provided in vessel 10, as shown in FIGURE 4. A pivot support 34 extending longitudinally of the vessel 10 is provided at the lower end of the compression legs 32. The wells 33 in the vessel 10 provide clearance so that the compression legs 32 may turn about the pivotal supports 34 as the vessel 10 rolls about its axis of oscillation 35. The derrick 36 used in drilling operations is carried on the support bridge 31. The derrick 36 may optionally be located as shown at the phantom line position 36', in which latter case the drilling operations would be performed through an opening (not shown) extending entirely through the vessel 10.

The support bridge 31 has one end 37 which terminates in a position above the central portion of the vessel 11. A tension bar 38 is connected to the end portion 37 of the support bridge 31 by means of gimbal joint 39. The upper end of the tension bar 38 is connected by a gimbal joint 40 to the tower 41 rigidly attached to vessel 11.

In a conventional floating apparatus for drilling operations beneath a body of water, the derrick is rigidly attached to the floating vessel. As a result, rolling action of the vessel in response to wind and wave action produces exaggerated motion at the top of the derrick. Since the weight of the drill pipe and related drilling equipment is suspended from the top of the derrick, such motion may be sufficiently severe to require suspension of drilling operations until the weather becomes more calm. It is also evident that the operations within the remaining portions of the derrick as well as the derrick floor and the equipment supported thereby will be adversely affected by such rolling motion of the floating vessel.

When a floating vessel rolls in response to wind or wave action, the effect is that that entire vessel pivots through a small angle of rotation, for example one degree to fifteen degrees about an axis 35 commonly known as the axis of oscillation. It is apparent that any structural elements or items of equipment that are rigidly attached to the floating vessel will also be forced to turn about this same axis of oscillation. The further the item of equipment is located from the axis of oscillation, the greater its motion will be. Conversely, the closer it is to the axis of oscillation, the smaller its motion will be.

In the embodiment of this invention as shown and described herein, the two spaced fioating vessels may independently roll with wind and wave action, but very little of this rolling motion is transmitted to the support bridge 31 on which the derrick 36 is mounted. The pivot support assemblies 34 are located at or near the axis of oscillation 35 so that rolling motion is at a minimum. The support bridge is rigidly attached to the compression members 32 and hence the support bridge is pivotally mounted near the axis of oscillation 35 of the vessel 10. The end 37 of the supported ridge 31 is pendantly supported from the tower 41 on the other vessel 11 by means of the tension bar 38 and gimbal joints 39 and 40.

It should be noted that it is not necessary that the pivotal supports 34 be located exactly on the axis of oscillation of the vessel 10. Derricks commonly in use on floating vessels may be from 100 feet to 150 feet high. M-otion at the top of the derrick is approximately equal to the height of the derrick multiplied by the angle of roll. If the pivotal assemblies 34 were placed approximately or feet above the axis of oscillation 35 of the vessel 10, motion of the parts 34 would be equal to the respective distances from the axis of oscillation 35 multiplied by the angle of roll. Thus it is evident that the pivotal supports 34, support bridge 31 and derrick 36 would move only one tenth as much at the top of the derrick as compared to the conventional mounting of the derrick by rigid attachment to one of the vessels. From the foregoing it is evident that a very significant reduction in the motion caused by rolling can be achieved by the apparatus of this invention.

The connection between the gimbal joint 39 and the end 37 of the support bridge 31 is preferably positioned above the central portion of the vessel 11. The pendant support supplied by the tension member 38 tends to restore the system to the original position which the parts would occupy during calm weather. Thus there are forces of restitution which tend to minimize and damp out any motion of the support bridge 31 which might be caused by rolling of vessel 10.

It is of particular importance to note that the pivotal supports 34, mounted on or near the axis of oscillation of vessel 10, in conjunction with gimbal joint 39 on vessel 11, determine a plane which in turn establishes a plane of support for the derrick and related equipment which is relatively free of motion which might otherwise be induced because of rolling of vessel 10. This result is achieved primarily because gimbal joint 39, supported by vessel 11 and attached to one end of the framework 31, enforces turning motion around pivotal supports 34 as vessel 10 rolls.

The vessel 10 may be maintained in the desired offshore position by means of the anchor cables 45 and winches 46.

Having fully described my invention, it is to be understood that I am not to be limited to the details herein set forth but that my invention is of the full scope of the appended claims.

I claim:

1. Floating support apparatus having in combination: two buoyant members, means spacing the members apart so that they may each roll and pitch independently of the other, a bridge extending laterally to span the space between the two buoyant members, pivot means supporting one portion of said bridge on one of said buoyant members near its longitudinal axis of oscillation, a tower on the other buoyant member, and pendant means supporting another portion of said bridge from said tower.

2. Floating support apparatus having in combination: two buoyant members, means spacing the members apart so that they may each roll and pitch independently of the other, a bridge extending laterally to span the space between the two buoyant members, one of the buoyant members having a well in the upper portion thereof, pivot means in said well supporting one portion of said bridge on said buoyant member near its longitudinal axis of oscillation, a tower on the other buoyant member, and pendant means including a tension member supporting another portion of said bridge from said tower.

3. Floating support apparatus having in combination: two floating vessels, means spacing the vessels apart so that they may each roll and pitch independently of the other, a bridge extending laterally to span the space between said vessels, longitudinally spaced pivot means supporting one portion of said bridge on one of said vessels near its longitudinal axis of oscillation, a tower on the other of said vessels, and pendant means supporting another portion of said bridge from said tower.

4. Floating support apparatus having in combination: two floating vessels, means spacing the vessels apart so that they may each roll and pitch independently of the other, a bridge extending laterally to span the space between said vessels, said bridge having spaced compression members, longitudinally spaced pivot means supporting said compression members on one of said vessels near its longitudinal axis of oscillation, a tower on the other of said vessels, and pendant means supporting an extending end of said bridge from said tower.

References Cited UNITED STATES PATENTS 942,687 12/1909 White 11461 2,119,775 6/1938 Chase 11461 2,916,002 12/ 1959 Hunsucker 1140.5 3,039,416 6/1962 Ducommun l1461 MILTON BUCHLER, Primary Examiner.

T. M. BLIX, Assistant Examiner.