FR2562026A1 - SHIP COMPRISING THREE SEMI-SUBMERSIBLE FLOATS - Google Patents

Abstract

THE INVENTION RELATES TO A SHIP CONTAINING THREE SEMI-SUBMERSIBLE FLOATS CONNECTED TO A DECK BY LEGS, A CENTRAL FLOAT 3 BEING AVAILABLE FORWARD AND TWO SIDE FLOATS 8 BEING ARRANGED SYMETRICALLY WITH RESPECT TO THE LONGITUDINAL PLANE OF THE CENTRAL FLOAT. ACCORDING TO THE INVENTION: A. THE RATIO OF ORDER AI OF THE CURVE OF AREAS A1 OF THE VESSEL AT THE CROSSING POINT 1 OF THE CURVES OF AREAS A3 AND A5 OF THE SIDE FLOATS ON THE ONE HAND, AND OF THE CENTRAL FLOAT ON THE OTHER HAND , AT THE MAXIMUM ORDINATE AM1 OF THE SAID CURVE OF THE SHIP AREAS IS AT LEAST EQUAL TO 0.45; AND B. THE RATIO OF THE SUM OF THE VOLUMES OF THE SIDE FLOATS TAKEN TOGETHER ON THE ONE HAND TO THE VOLUME OF THE CENTRAL FLOAT ON THE OTHER HAND IS BETWEEN 0.3 AND 1.7. AN APPLICATION IS THE REALIZATION OF AN ECONOMICAL OPERATING VESSEL.

Description

Ship with three semi-submersible floats We already know

  some achievements, and many more projects of surface ships whose buoyancy is ensured by several -two, three or four - fully submerged hulls connected to the rest of the ship by partially immersed legs that participate in the buoyancy. The useful part of such a ship is

  placed above the surface of the water and

  Normally, all of a hull proper and part of the leg immersed by the word

of "semi-submersible float".

  This design of ships is recent, the ships actually built are few

  numerous and the experience gained is incomplete.

  This new design is however

  promising for the realization of navi-

  with good seaworthiness and stability

  tisfaisante. It is still necessary to define the

  particular positions to obtain the

  minimum advancement and, consequently, the production of economic vessels for their exploitation.

  The object of the present invention is, in particular

  optimizing the shapes and locations of

  semi-submersible floats, by defining such

  the new special provisions.

  The subject of the invention is therefore a vessel comprising three semisubmersible floats connected to

  a bridge by legs, a central float being

  placed in front and two lateral floats being

  symmetrically with respect to the longitudinal plane

of the central float.

  In this ship, (a) the ratio of the ordinate of the curve of the ship's areas to the point of intersection of the curves of the areas of the lateral floats, on the one hand, and the central float, on the other, to the the maximum ordinate of said curve of the areas of the ship is at least 0.45; and, b) the ratio of the sum of the volumes of the side floats taken together on the one hand, to the volume of the central float on the other hand is

between 0.3 and 1.7.

  The advantageous following provisions are furthermore preferably adopted: the two lateral floats are on the one hand identical, and on the other hand they are distinct from the central float; - the ship's dissymmetry coefficient is less than 0.3;

  - at least a substantially horizontal fin

  it connects each lateral float to the central float; the lengthening of each float is between 5 and 10; - for each float, the ratio of the

  depth.Inversion of the maximum of the curve of

  horizontal sections (ie TcL), to the diameter

  equivalent of said float is between 0.6 and 1.4.

  The invention will be better understood, and

  secondary characteristics and their perceived advantages

  will be in the course of the description of

  given below as an example.

  It is understood that the description and

  drawings are only indicative and not

  mitatif. Reference will be made to the accompanying drawings in which: FIG. 1 is a view, along arrow F of FIG. 2, of a ship according to the invention; - Figure 2 is a view along arrow G of Figure 1, the same ship; - Figure 3 is a section III-III of Figure 1; - 3 -

  - Figures 4,5,6,7 and 8 are the letters

  besides ship areas according to the invention, se-

  Ion several distinct embodiments.

  Reference is made hereinafter to certain concepts, including the unusual nature of the

  definition, which is carried out in the attached annex.

  te, which is part of the patent application.

  The vessel represented is a ship of

  surface, of the type comprising three floats, said

  maran ".It consists of: - a fully emerged body 1, including a bridge 2 and housing the useful volume of the ship (cargo holds, cabins, various premises) - a central front hull 3, which is

  oblong has a vertical longitudinal plane of symmetry

  trie S, and is fully imoergée below the surface of the water 4;

  two lateral hulls 5, which are

  laid asymmetrically with respect to the plane of symmetry S, behind the central shell 3 are identical and fully immersed;

  a leg 6, which extends vertically,

  substantially parallel to the plane of symmetry S and

  binds the central shell 3 to the lower face 7 of the emerging body 1;

  - two legs 8, which extend vertically-

  substantially parallel to the plane of symmetry S

  and, which each connect a side shell 5 to the

  this lower 7 of the body 1 - two substantially horizontal fins 9, which connect one, one of the side shells 5, the other,

  the other side shell 5 to the central hull 3.

  The following features are observed: - the set of a shell and the corresponding leg (central shell 3 and leg 6, each - 4 side shell 5 and leg 8) is a semi-submersible float; each semi-submersible float has positive buoyancy, all three semi-submersible floats providing the vessel with buoyancy;

  - the 3.5 hulls and their legs 6.8 can

  consist of reservoirs, water-ballast

  but may also consist of compartments

  containing the ship's facilities; thus, three engines "Diesel" type, one main, two of lower power, can be installed in the central hull 3 and in the side hulls, and drive propellers propellers; of

  even the hollow legs 6.8 are able to make

  sible the passage of many connections (electrical cables, pipes, access) connecting the hulls 3,5 to the bridge 2;

  - transverse vertical planes that do not

  the ends of the curves of the immersed areas.

  vertical cross-sections of the

  semi-submersibles 3-6 and 5-8 are identified: V 3 R: plane passing through the rear end of the curve of the areas of the semi-submersible float 36,

  V 3 AT: plane passing Dar the front end of the yard

  be areas of the semi-submersible float 3-6,

  V 5 AR: plane passing through the rear ends of the yard

  be areas of semi-submersible floats 5-8, V 5 N: plane passing through the front ends of the semisubmersible float area curve 5-8,

  and we note that a recovery in the longitudinal direction is achieved

  dinal, parallel to the plane S, relative positions of the flow-

  3-6 central semi-sub- sible loader and semi-sub-

  5 to 8, the plane V 5AV being disposed in front of the plane V 3 R. FIGS. 4 to 8 show the curves of the areas according to several distinct embodiments and corresponding for each embodiment: the curve A 5 to set of two semi-submersible floats 5-8,

  the curve A 3 with the semi-submersible float

  3-6, and, - the curve A 1 to all three semisubmersible floats, that is to say to the ship itself.

  As a result of the above-mentioned recovery, the Courts

  bes A 3 and A 5 have a point of intersection i contained in a transverse vertical plane VI, located between the planes V 3 R and V 5 X. Are further represented: - the value AI of the cross sectional area of the ship (curve A1) located in the plane

VI,

  the maximum values AM3 and AM5 of the curves A3 and A5,

  the maximum value AM1 of the curve AI.

  In the embodiment corresponding to FIG. 4, AI is substantially equal to AM3 and AM45. AM1 is therefore equal to substantially any one of these three values. Curve A1 is flat between planes V3R and V5A. This is very favorable to obtaining

  low wave resistance for correct speeds

  corresponding to a Froude number of about 0.4 to 0.6 (A1 curve "balanced" between the front and the rear of the vessel and free of any accentuated pits or peaks, notably in the area of Plan VI)

  In addition, the volum of the two semi-submersible floats

  On the one hand, and the voltme of the central semi-submersible float 36, on the other hand, are substantially equal (surfaces of the curves of areas A3 and A5 being substantially equal), which makes it possible, in the trimaran arrangement adopted, to minimize even more

wave resistance.

  Although the solution of the embodiment of FIG. 4 can appear from these points of view with regard to an ideal solution, it remains obvious, however, that other solutions can be

  less good, are also satisfactory.

  Thus in the embodiment of Figure 5, AM1 = AM5; AM3 is slightly lower than AM5 and AI / AM1 = 0.45. The volumes of the lateral semi-submersible floats 5-8 and central 3-6 are substantially equal. This is a limit achievement, suitable for high speeds (Fn> 0.6), Ai / AM1 to be chosen in principle greater than 0.45 to allow the maximum reduction

wave resistance.

  The embodiment of FIG. 6 is characterized by a strong imbalance of the volumes of lateral semi-submersible floats 5-8 of a

  part of the central semi-submersible float 3-6 of

  on the other hand: the ratio of these volumes is equal to 0.3.

  Again, this is a lower limit below

  from which it is advisable not to descend. In addition

  their AI / AMi is substantially equal to 1, which is satisfactory. Figure 7 shows an embodiment

  in which the volume of the semi-submersible floats

  side (and back) wounds. 5-8 is equal to 1.7 times

  him from the semi-submersible.central float (and before) 3-6. This realization constitutes the upper limit not to be exceeded. Moreover, AI is substantially

  equal to AM1. The curve Ai is relatively flat between the

  put A3 and A5 bends, resulting in a relatively low wave resistance for the speeds corresponding to

Fn = 0.4 to 0.6.

  FIG. 8 represents an embodiment in which the curve of the A1 areas of the ship has a strong

  dissvmétrie. The DIS.dissimetrie coefficient of the navi-

  re is equal to 0.3, which is the limit on

  below which it is better to stay. Lateral semisubmersible floats (and -7 -

  back) 5-8 are belly-bellied relative to the sub-float

central mersible, before 3-6.

  For the vessel shown in FIGS. 1 to 3 (semisubmersible floats 3-6 and 5-8 in continuous lines of FIG. 1), the coefficient of elongation of said floats is approximately equal to 7. To obtain a compromise between the resistance of wave and resistance

  of friction minimizing the resistance to total advance, it con-

  just chose the shapes for the coefficient

  of elongation is between 5 and 10.

  Finally, to draw from this technique semi-submersible floats the maximum benefits, it is appropriate, on the one hand to immerse the floats 3-6; -8 at depths sufficient to reduce the movements of the vessel and decrease the resistance of the vessel, on the other hand to limit the immersion of said floats to depths making the construction of the ship free of significant structural problems and maintaining the surface wet at a reasonable value. That's the reason

  for which the TcL / Deq ratio of the depth of

  the maximum of the curve of the areas of the

  horizontal dimensions by the equivalent diameter is

  taken, for each semi-submersible float, between 0.6 and 1.4 which corresponds to the dashed line drawings of FIG. 1, the drawing of the floats closest to the surface of the water correspond to

  at TcL / Deq = 0.6 and the one farthest from the surface

  this water corresponding to Tcl / Deq = 1.4.

  The definition of the ship that has just been

  carried out gives this vessel qualities that are well

  of all the semi-submersible vessels, but also a new optimization of its resistance to

  advancement. For the first time, a semi-

  submersible has a substantially equivalent efficiency

  slow to that of a classic surface ship likewise

  tonnage, which makes this technique viable.

  In comparison with semi-submarine

  catamaran type mersibles, wave resistance

  is significantly lower because on the one hand, the allon-

  of the three semi-submersible floats may be

  more favorable than that of the two semi-sub-

  catamaran mersibles, on the other hand, the choice of the longitudinal overlap of the A3 and A5 curves avoids annoying interferences between the flows along the semisubmersible float

  central 3-6 and semi-submersible floats la-

  5-8, and, again, to reduce the resistance of waves. The choice of the curve of the A1 areas, preferably the flatter between the two peaks of the curves of the areas A3 and A5 and, in the vicinity of the

  point I is, on this point, an important reduction

  aunt of resistance to advancement.

  It must also be noted that the structure

  re recommended is particularly robust. We know that catamarans, for example, have generally fragile structures, given the very

  important ones that develop there. The new structure

  "trimaran" type, which is proposed does not present this previously known fragility because on the one hand the ship is generally supported on 3 points

  instead of 4 for catamarans, on the other hand

  lerons 9 close the structure formed by the legs 6 and 8 and the shells 3 and 5. Thus, the forces in the zone of the attachment of the legs 6 and 8 to the body 1 are much lower than those existing in the zones

  equivalents for connecting the floats of a

  semi-submersible tamaran at the center point of said catamaran.

  The invention is not limited to the

  represented, but on the contrary covers all

  the variants that could be made to them

  without leaving their frame or their minds.

ANNEX

  This annex is mainly intended

  to clarify the definitions adopted from a few

my used.

  Curve of the areas of a ship The submerged part of the hull of a ship is usually defined by the values of its sections

  vertical transverse lines between the vertical

  passing them through the extreme emerge points of the hull, say PPAV and PPAR in the direction of the length of the ship. The

  report, on the ordinate, of the cross-sectional areas

  and on the x-axis of the distances of said cross sections to a reference origin,

  allows to establish the curve of the areas.

  Volume of a semi-submersible float -

  This volume is equal to the surface delimited on the graph representing the curve of the areas of the vertical transverse sections, by this curve of

areas and the x-axis.

  Semi-submersible float A submerged body can be defined, at least

  partially, by horizontal sections.

  A semi-submersible float means such a body with a positive buoyancy, the curve of the areas of its horizontal sections (or lines of water) has a maximum below the surface of the water

at a TCL depth.

  In such a float, the value of this maximum

  mum is preferably greater than twice the

  their area of the - horizontal section at the waterline.

  This maximum can be achieved for various depths of water lines. In this case, TCL designates

  the arithmetic mean of said depths.

  In a banal way, a semi-submarine float

  mersible is constituted by the whole of a hull totally immersed and of a leg connecting it with

less the surface of the water.

  Equivalent diameter It is often difficult to distinguish the leg from the fully submerged hull to which

  she is connected. It is then advantageous to

  Deq diameter of a circle whose area is equal to that of the maximum cross section of the semi-submersible float (leg + hull assembly

totally immersed).

  Lengthening of a semi-submersible float Lengthening is the ratio of the length

  of the curve of the cross-sectional areas of the

  tical to the equivalent diameter of this semi-sub-

  mersible. Coefficient of dissymmetry

  The curve of the areas of the transverse sections

  verticals of a float extends along the length

  total of this float, ie x, the abscissa, identifying the position of a vertical cross section, measured

  from an origin O located at the abs-

  median curve of the area curve.

  The median abscissa of the curve of

  res is the abscissa of the trans section

  vertical versale that separates the ship

in two equal volumes.

  A (x), the value of the area of the trans-

  vertical versal corresponding to the abs-

  cisse x; V, the total volume of the submerged portion of the float

  Xav, abscissa from the front end of the yard

be areas.

  Xar: abscissa of the rear end of the area curve Xmax: greater of the two values Xav and Xar The longitudinal dissymmetry of the float

  corresponds to the differences in the values of the

  vertical cross-sections corresponding to

  x and (x), symmetrical with respect to the original

X-axis.

  The quantity fmo is a representation of this asymmetry. She has

  the dimensions of a volume and it is possible, and na-

  turly preferable, to transform it to obtain

  a dimensionless coefficient. For this purpose,

  re, divide it by the volume V of the float.

  With j (l) the dissymmetry coefficient DIS of a float is defined by the equality: I I '

- 13 -

Claims (6)

  1. Ship having three semi-submersible floats (3-6; 5-8) connected to a bridge (1,2) by legs (6; 8) a central float (3-6) being arranged in front and   two lateral floats (5-8) being arranged symmetrically   only with respect to the longitudinal plane (S) of the central float, characterized in that: a) the ratio of the ordinate (AI) of the curve of the areas (A1) of the ship to the point of intersection   (I) curves of the areas (A3 and A5) of the floats la-   On the one hand, and the central float, on the other hand, at the maximum ordinate (AM1) of said curve of the areas (A1) of the ship is at least 0.45; (b) the ratio of the sum of the volumes of   side floats taken together on the one hand, at the   me of the central float on the other hand is between 0.3 and 1.7.   2. Ship according to claim 1, characterized in that the two lateral floats (5-8) are on the one hand identical, on the other hand distinct from the central float (3-6).   3. Ship according to any one of the   cations 1 and 2, characterized in that its coefficient   dissymmetry (DIS) is less than 0.3.   4. Ship according to any one of the   cations 1 to 3, characterized in that at least one wing-   substantially horizontal plane (9) connects each float   lateral (S) to the central float (3).   Ship according to any of the claims   cations 1 to 4, characterized in that the elongation of   each float is between 5 and 10.   6. Ship according to any one of the   cations 1 to 5, characterized in that for each   the ratio of the immersion depth of the maximum - 14 -   mum of the curve of the areas of the horizontal sections (TcL), to the equivalent diameter (Deq) of said float is between 0.6 and 1.4.