Abstract:
A semisubmersible trimaran for use in an afloat sea base is disclosed. The trimaran has an upper deck structure 12 supported on a longitudinal center hull 26 and column-stabilized, longitudinal outrigger pontoons 28. The center hull 26 and pontoon columns 38 and 40 have a reduced waterplane area for minimizing motion during operations. The trimaran has a transit draft 37 for deployment at full waterplane area, and an operating draft 36 with a reduced waterplane area for damping motion. The vessel can be deployed with a transit drive 42 on the hull 26, and dynamically positioned at a destination for operations. Multiple trimarans can be assembled to provide an extended upper surface, including a landing area for fixed-wing aircraft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority to U.S. Provisional Application 60/320,005, filed in the United States Patent and Trademark Office on Mar. 12, 2003. 
     
    
     BACKGROUND OF INVENTION  
       [0002]     The present invention is directed to a marine platform structure, and particularly to a semisubmersible trimaran with an upper deck supported on a center hull and column-stabilized outrigger pontoons.  
         [0003]     It has been proposed to use large marine platform structures as one component in an afloat sea base comprising perhaps a dozen other specialized structures and/or vessels. The marine platform structure would contribute to the capabilities of the afloat sea base in providing logistics and basing functionality, e.g. cargo transfer and warehousing facilities, fuel and water storage, aircraft landing and takeoff facilities, marine vessel and aircraft repair facilities, vehicle storage and repair facilities, personnel housing, hospital, off-shore basing for security operations, and the like.  
         [0004]     Such a structure must be deployable to a stationing location at a reasonable transit speed, and yet must be able to stay in position with low motion characteristics in variable wind, wave, and weather conditions. The structure must be stable both during transit and in operation.  
         [0005]     Semisubmersible marine structures are well known in the oil and gas industries. Such structures are typically only moveable by towing. These semisubmersibles have a relatively low transit draft that allows them to be floated to a stationing location, where they can add ballast, usually by taking on seawater, to assume a relatively deep draft or semisubmerged condition for operation.  
         [0006]     Flotation of semisubmersibles is usually accomplished with pontoons on which an upper deck is supported by columns. The pontoons provide a relatively large waterplane area, as is desirable for transit, but when submerged for stationing, the columns connecting the pontoons to the upper deck present a lower waterplane area for operation. The low waterplane area is desirable to reduce motion characteristics from waves, especially during swell seas and storms. The upper deck from which rig activities are conducted must be maintained above the water plane at all times.  
         [0007]     U.S. Pat. No. 5,823,130 to Kreyn et al. discloses a catamaran or trimaran-style vessel for shipping a combination of liquids and containerized cargo. Two or three longitudinal hull sections providing internal tanks for storage of liquids are connected by a deck surface on which to stack cargo containers.  
         [0008]     Small waterplane area tri-hull ships or SWATH vessels, have been used as ferries for cars and passengers, cruise vessels, oceanographic research, patrolling, and other off-shore crew service functions. The SWATH acronym has also been applied in trade terminology to twin-hull vessels. Some 50 commercial SWATH vessels have been placed in service worldwide, with displacements typically below 1,000 tons. However, there is a SWATH cruise ship having a displacement of about 11,500 tons.  
         [0009]     A SWATH type ship for use in cleaning oil-slicks is currently being developed by Alstom. The trimaran features a large slender central hull, and two lateral stabilizing hulls. Oil is collected from the surface of the water between the hulls, where the area between the hulls is protected from the current allowing stabilization for improved collection. The ship is designed to operate in gale force conditions and can hold up to 6000 metric tons of collected oil.  
         [0010]     U.S. Pat. No. 6,550,408 to Janssen discloses methods and apparatus for more economically loading/unloading cargo from a multi-hull ship. Janssen teaches a design of SWATH ships having no interior cargo holds, and using surfaces of a segmented, submersible platform for stowing floatable cargo.  
         [0011]     U.S. Pat. No. 6,378,450 to Begnaud et al. discloses a towed, semi-submersible, twin-hull pontoon structure with four corner caisson columns. The caissons are connected by horizontal braces to reduce spreading and torque-inducing forces. The structure can support an off-shore drilling unit for use in moderate or severe conditions, employing thruster assemblies for dynamic station keeping.  
         [0012]     U.S. Pat. No. 6,374,764 to Davenport et al. discloses an apparatus and method for installing a deck on an offshore substructure, such as for example, a drilling station for oil or gas production. The patent discloses a self-floating apparatus with pontoons which support a self-jacking deck.  
         [0013]     U.S. Pat. No. 6,341,573 to Buck provides a ship able to be converted into a floating aircraft runway, supported on slender, buoyant hull/spar legs that pivot downward from a retracted horizontal configuration to a vertical configuration. Multiple vessels are connected together for stationing.  
         [0014]     U.S. Pat. No. 3,939,790 to Varges et al. and U.S. Pat. No. 4,147,123 to Kirby et al. disclose flotation methods and monohull ship designs for loading and unloading floatable cargo such as barges.  
         [0015]     U.S. Pat. No. 6,532,884 to Profitt et al. discloses designs for various high-speed watercraft, driven by electric motors. The designs generally relate to small craft, such as for example pleasure boats, featuring a submersible center hull and two adjacent, floatable skis on adjustable struts vertically moveable to control the hull submersion.  
       SUMMARY OF INVENTION  
       [0016]     The present invention is a semisubmersible trimaran that can be stable during transit and can have a reduced waterplane area for inhibiting motion during on-station operations. The semisubmersible trimaran has favorable motion characteristics and capability for supporting large payloads. The outrigger characteristics, small waterplane area, and buoyancy characteristics can enhance transit speed. A combination of large payload capacity, enhanced speed characteristics, and basing capability give the semisubmersible trimaran both commercial and tactical advantages over conventional marine platforms and vessels. In particular, the semisubmersible trimaran provides basing capability for relatively larger fixed-wing aircraft for landing/takeoff, storage, and maintenance, e.g. compared to conventional ship-based aircraft.  
         [0017]     In one embodiment, the invention provides a semisubmersible trimaran having an upper deck structure supported on a longitudinal center hull and a pair of column-stabilized, longitudinal outrigger pontoons laterally spaced from the center hull on opposite sides thereof. The upper deck structure can have a thickness of at least about 20 meters. The semisubmersible trimaran can include a superstructure and/or a runway on an upper surface of the deck structure. A plurality of the semisubmersible trimarans in an end-to-end assemblage can form an afloat seabase. The trimaaran can also include a ballast control system to adjust a draft of the trimaran between a relatively shallow transit draft and a relatively deep operating draft, and to regulate trim and list of the trimaran.  
         [0018]     Desirably, the operating draft can be from about 180 to 220 percent of the transit draft. The center hull can include a full waterplane area of the hull at the transit draft and a reduced waterplane area of the hull at the operating draft. Desirably, the reduced waterplane area of the center hull can be from 40 to 65 percent of the full waterplane area of the hull, a full waterplane area of the outrigger pontoons at the transit draft can be from 3 to 5 times a reduced waterplane area of the outrigger support columns at operating draft, and a total reduced waterplane area of the trimaran at operating draft is from 35 to 60 percent of a total full waterplane area of the trimaran at transit draft.  
         [0019]     The outrigger support columns can include columns spaced fore and aft extending upright from the outrigger pontoons to the upper deck structure. The semisubmersible trimaran can include a transit propulsion drive on the center hull selected from propeller screws, thruster pods, and the like, and combinations thereof. A plurality of dynamic positioning drives can be provided on the pontoons, desirably retractable for transit streamlining. The trimaran can also include a marine docking facility on the center hull, or a marine berthing facility adjacent at least one of the pontoons.  
         [0020]     The semisubmersible trimaran desirably has an operating displacement from about 120 to 200 percent of a transit displacement, and an available operating deadweight is at least twice an available transit deadweight. The upper deck structure can have a length from about 1.5 to 2.1 times a width thereof, and a length of the center hull can be from about 150 to 200 percent of a length of the outrigger pontoons.  
         [0021]     In another embodiment, the invention provides a semisubmersible trimaran having: (a) an upper deck structure supported on a longitudinal center hull and first and a second outrigger pontoons, wherein the outrigger pontoons each depend from a plurality of upright columns and are laterally spaced from the center hull on opposite sides thereof; (b) a ballast control system to adjust a draft and to regulate trim and list of the trimaran; and (c) full and reduced waterplane areas at transit and operating drafts, respectively, of the center hull and the outrigger pontoons and columns, wherein the reduced waterplane area of the center hull comprises from 40 to 65 percent of the full waterplane area of the hull, and the full waterplane area of the outrigger pontoons comprises from 3 to 5 times the reduced waterplane area of the columns.  
         [0022]     In another embodiment the invention provides a semisubmersible trimaran including; (a) an upper deck structure supported on a longitudinal center hull; (b) a first longitudinal outrigger pontoon and a second longitudinal outrigger pontoon, said first and second outrigger pontoons laterally spaced from the center hull on opposite sides thereof, wherein the outrigger pontoons are stabilized by a plurality of columns connected to the deck structure; (c) a transit propulsion drive on the center hull selected from propeller screws, thruster pods, and combinations thereof; and (d) a plurality of dynamic positioning drives on the pontoons. The trimaran can include a ballast control system to adjust a draft of the trimaran between a relatively shallow transit draft with a full waterplane area and a relatively deep operating draft with a reduced waterplane area comprising from 35 to 60 percent of the full waterplane area.  
         [0023]     Another embodiment of the invention provides a semisubmersible trimaran having: (a) an upper deck structure supported on a longitudinal center hull; (b) a pair of column-stabilized, longitudinal outrigger pontoons laterally spaced from the center hull on opposite sides thereof; (c) a ballast control system to adjust a draft of the trimaran between a relatively shallow transit draft with a full waterplane area and a relatively deep operating draft with a reduced waterplane area comprising from 35 to 60 percent of the full waterplane area; and (d) a marine docking facility below the upper deck structure on the center hull or one of the outrigger pontoons accessible at the operating draft.  
         [0024]     A further embodiment of the invention provides a semisubmersible trimaran including: (a) a central hull with a bow, a stern, and side walls providing a series of buoyancy compartments; (b) a deck structure supported on the central hull, said deck structure having fore and aft portions, port and starboard wings, and top and bottom surfaces defining a storage space therebetween; (c) first and second pontoons each connected to the deck structure by a plurality of columns, said first pontoon laterally positioned beneath the port wing, said second pontoon laterally positioned beneath the starboard wing; (d) liquid storage compartments in the central hull and pontoons; and (e) a ballast control system comprising ballast tanks in the hull and pontoons to control a draft of the trimaran between a relatively shallow transit draft and a relatively deep operating draft. The semisubmersible trimaran desirably has a full waterplane area at the transit draft, and a reduced waterplane area at the operating draft that is from 35 to 60 percent of the full waterplane area. The trimaran can also have a runway to launch and land fixed wing aircraft on the upper deck structure. An afloat seabase can be formed from a plurality of the trimarans connected end-to-end to align the runways. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0025]      FIG. 1  is a plan view of an upper deck of a semi-submersible trimaran according to an embodiment of the invention.  
         [0026]      FIG. 2  is a sectional plan view of the center hull and outrigger pontoons of an embodiment of the inventive semi-submersible trimaran of  FIG. 1 .  
         [0027]      FIG. 3  is a sectional elevation of an embodiment of the semisubmersible trimaran, as seen along line  3 - 3  of  FIG. 2 .  
         [0028]      FIG. 4  is an elevation view of the center hull of an embodiment of the trimaran, as seen along line  4 - 4  of  FIG. 2 .  
         [0029]      FIG. 5  is a perspective view of a semisubmersible trimaran according to an embodiment of the invention, as seen from below forward starboard.  
         [0030]      FIG. 6  is a perspective view of the semisubmersible trimaran of  FIG. 5 , as seen from above aft port.  
         [0031]      FIG. 7  is a perspective view of an embodiment of the semisubmersible trimaran of  FIGS. 5-6  from above forward port, showing vessels berthing for loading and unloading.  
         [0032]      FIG. 8  is a perspective view of an alternative embodiment of the semisubmersible trimaran of  FIG. 7 , viewed from above forward starboard.  
         [0033]      FIG. 9  is a perspective view of an embodiment of the invention showing two semisubmersible trimarans docked together bow-to-stern to form an extended surface.  
         [0034]      FIG. 10  is a perspective view of an embodiment of the invention showing two semisubmersible trimarans docked together stern-to-stern to form an extended surface. 
     
    
     DETAILED DESCRIPTION  
       [0035]     With reference to the figures, wherein like parts are referred to with like numerals,  FIG. 1  shows a semisubmersible trimaran  10  according to one embodiment of the invention. An upper deck structure  12  presents an upper surface with generally straight-sided wings  14  and ends  16 , with forward corner section  18  and aft corner section  20 , extending therebetween to complete a perimeter. The wings  14  are disposed partially aft of a transverse center-line  21 , such that the forward corner sections  18  are more oblique than the aft corner sections  20 , relative to a longitudinal axis  22  of the trimaran  10 .  
         [0036]     The upper surface of the deck  12  can include a longitudinal runway (not shown) at a central area for landing and takeoff of fixed wing aircraft, and a superstructure  24  disposed adjacent to one of the sides or wings  14 , e.g. to starboard as shown in  FIG. 1 . The trimaran  10  can include one or more interior deck sections (not shown), such as for example, a 9-meter upper deck section, two 3.5-meter intermediate deck sections, and a 4-meter lower deck section.  
         [0037]     With reference to  FIGS. 2-4 , the deck  12  is supported on a center hull  26  and outrigger pontoons  28 . The center hull  26  can run the length of the trimaran  10  from bow  30  to stern  32  adjacent the longitudinal axis  22 . The bow  30  can be conventionally streamlined to facilitate reduced resistance and enhanced transit speed. As best seen in  FIG. 3 , the center hull  26  has a reduced waterplane area in a hull riser section  32  intermediate the deck  12  and a lower hull section  34  of full waterplane area. The hull riser section  32  can have a reduced width and length relative to the lower hull section  34 . In transit, running at a relatively shallower draft, a transit water level  37  is at the lower hull section  34  for a larger waterplane area. In on-station operation, with a relatively deeper operating draft, an operating water level  36  can correspond to the reduced waterplane area of the hull riser section  32 .  
         [0038]     The outrigger pontoons  28  are disposed longitudinally on either side of the center hull  26  and support fore and aft columns  38 ,  40 , respectively, extending from the deck  12  adjacent an outer edge of the wings  14 . The columns  38  and  40  present a reduced waterplane area corresponding to the operating water level  36 , whereas the pontoons  28  provide a larger, full waterplane area at the transit water level  37 . If desired, the pontoons  28  and columns  38  and  40  are shaped to minimize drag or wave resistance, as best shown in  FIG. 2 .  
         [0039]     The center hull  26  can have a length/breadth ratio of from 6 to 9, desirably from 7 to 8, more desirably about 7.4; and a length/depth ratio of from 5 to 9, desirably from 6 to 8, more desirably about 6.9. The pontoons  28  can have a length/breadth ratio of from 8 to 12, desirably from 9 to 11, more desirably about 9.7; and a length/depth ratio of from 10 to 16, desirably from 12 to 14, more desirably about 13.3. An outrigger support column desirably has a length to breadth ratio of from 8 to 12, especially about 9.6.  
         [0040]     For transit, one or more screw drives  42  or thruster pods (not shown) are mounted aft on the center hull  26  to deploy the trimaran with conventional propulsion. Dynamic positioning drives  44  are disposed at multiple locations, desirably fore and aft on each pontoon  28 , for positioning the trimaran  10  during operations. The dynamic positioning drives  44  can independently rotate 360 degrees in a horizontal plane to provide directional thrust as needed for operational stationing, and are desirably retractable for streamlining during transit. During operation, it is desirable to dynamically maintain a vessel heading such that waves break on the bow  30  or stern  32  and do not broadside the pontoons  28  and center hull  26 .  
         [0041]     An anchor  46  or other mooring device can be attached via line  48 , desirably for single-point mooring, e.g. at the bow  26 .  
         [0042]     The trimaran  10  assumes various drafts for different purposes, generally controlled by a ballast officer or ballast system controller by taking in or releasing seawater to adjust displacement. For loading or servicing the semisubmersible trimaran  10  on-station or in a port, for example, a minimum draft may be required. Ballast control is also useful to maintain a desired draft when the draft would otherwise change, for example in transfer of cargo (deadweight) to or from the trimaran  10 , or to different locations on the trimaran  10 . The trimaran  10  is trimmed and leveled by allocating ballast preferentially to port, starboard, fore, aft, etc., as needed, thereby balancing masses of deadweight and loads of the trimaran  10 .  
         [0043]     At sea during deployment to a station, the transit draft can be maintained, usually with the full waterplane area at the transit water line  37 . This posture minimizes drag and maximizes stability, speed, and efficiency in transit. Upon arrival on station, flooding ballast tanks in the center hull  26  and/or pontoons  28 , as necessary, achieves a displacement that attains the operating draft. This provides a reduced waterplane area to minimize transient movement from wave action, e.g. heave, roll, and pitch.  
         [0044]      FIGS. 5-6  show three-dimensional renderings in two perspectives of an embodiment of a semisubmersible trimaran  100  having improved motion characteristics. The upper deck structure  102  is supported on the center hull  104  and outrigger pontoons  106 . The center hull  104  includes the full hull section  108  supporting the riser section  110  of reduced length and width, relative to the full hull section  108 , to reduce the waterplane area at operating draft. The pontoons  106  support deck  102  and are attached via columns  112 . The columns  112  also present a reduced waterplane area at the operating draft.  
         [0045]     The center hull  104  and pontoons  106  have bows  114  and  116 , respectively for reduced drag, and bottom-sloped keels  118  and  120 , respectively. The riser section  110  can also have leading profiles or bows  122  shaped for reduced wave resistance. Similarly columns  112  can have leading profiles or bows  124  shaped for reduced wave resistance.  
         [0046]      FIGS. 7-8  show a semisubmersible trimaran  200  in two cargo transfer embodiments. The deck structure  202  provides berthing access for multiple vessels simultaneously. The operating waterline  204  is desirably above the full section of the center hull  206 , at the hull riser  208 . It is desirable that the waterline is maintained at a level sufficiently beneath the deck structure  202  to allow vessels, such as, for example, boats  210  to dock alongside the hull riser  208  for personnel or cargo transfer. If desired, a floodable deck (not shown) can be provided in the center hull riser  208 , for example, to facilitate transfer of floating cargo to/from onboard stowage, or to dry-dock marine vessels for maintenance.  
         [0047]     A roll-on, roll-off (RORO) transfer gangway  212  for motor vehicles and wheeled cargo can be provided, for example, at the stern  214  of the trimaran  200 , which is adapted for docking with a RORO vessel  216 . Containerized cargo transfer capability (lift-on/lift-off or LOLO) can be provided, for example, on at least one long side  218  of the upper deck structure  202 . The LOLO capability desirably includes a cargo bay  220  and crane hoists (not shown) for unloading a LOLO vessel  222  docked abreast the outrigger pontoons  221  and columns  223  of the trimaran  200 .  
         [0048]     If desired, a plurality of the semisubmersible trimarans  200  can be joined together in end-to-end embodiments, e.g. bow-to-stern  222 / 227  as in  FIG. 9 , stern-to-stern  227 / 227  as in  FIG. 10 , or bow-to-bow (not shown). The bow-to-bow embodiment has the benefit of allowing the concurrent conduct of RORO or other aft cargo transfer operation for the end-connected trimarans  200 . A connecting gangway  224  joins deck surfaces  202  and  202 A to provide a continuous, extended upper deck surface. In joining two or more trimarans, shown in  FIGS. 9 and 10  as  200  and  200 A, sufficient deck surface is provided for landing aircraft, such as, for example, fixed wing aircraft and vertical-takeoff-and-landing (VTOL) craft (not shown).  
         [0049]     According to one example of an embodiment of the invention, a semisubmersible trimaran substantially as shown in  FIGS. 1-4  has the following approximate dimensions A through Y:  
                                                   TABLE 1                           Example Semisubmersible Trimaran Dimensions.                    Reference in   Length           Feature   FIGS. 1-4   (m)                            Overall length (deck/center hull)   A   360           Overall width   B   200           Superstructure length   C   140           Superstructure width   D   30           Superstructure height   E   15           Superstructure offset from edge of   F   5           deck           Wing length   G   150           Wing offset from bow   H   135           Wing offset from stern   I   75           Deck width at bow   J   50           Deck thickness   K   20           Outrigger/center hull and deck   L   62           overall height           Pontoon/center hull main section   M   16           height           Center hull main section width   N   50           Center hull transition height   P   6           Center hull riser width   Q   37           Outrigger centerline-centerline   R   90           offset from central hull           Outrigger length   S   215           Outrigger width   T   22           Outrigger offset from stern   U   45           Outrigger offset from bow   V   100           Column width   W   18           Column Length   X   45           Column height   Y   36                      
 
         [0050]     At a transit draft of 14 m, the trimaran, having the approximate dimensions noted above, has a transit displacement of about 317,684 metric tons (mt) comprising available deadweight of about 106,851 mt. At a draft of 27 m, operating displacement is about 517,618 mt comprising available deadweight of about 306,785 mt. In the operating condition, the semisubmersible trimaran of this example has a metacentric height of 35.5 m, a keel to buoyancy center distance of 12.5 m, and a metacentric center of gravity of 11.8 m, indicating that the vessel is stable. In the transit condition, the semisubmersible trimaran has a metacentric height of 219.4 m, a keel-to-buoyancy-center distance of 8.0 m, and a metacentric center of gravity of 189.8 m.  
         [0051]     Fluid storage volume in the pontoons and columns is approximately 153,889 cubic meters (m 3 ) total volume at a permeability of 0.85, where “permeability” is a characteristic of physical area or volume defining usability thereof. Hence, there is a net usable fluid storage volume in the pontoons and columns of approximately 130,806 m 3 . Storage volume in the center hull is approximately 307,871 m 3  total volume at a permeability of 0.3, yielding a net useable volume of approximately 92,361 m 3 . The total net fluid useable storage volume in the trimaran structure is thus approximately 223,167 m 3 .  
         [0052]     Container storage area is approximately 17,556 m 2  total in the center section of the deck structure with a permeability of 0.1, for a net useable area of approximately 1756 m 2;  container storage area for each of the wing sections is approximately 11,472 m 2  with a permeability of 0.9 for a net useable area of approximately 10,325 m 2  in each wing section. The total net useable container storage area is thus approximately 22,406 m 2 . The RORO storage area for rolling vehicles is approximately 8823 m 2  in each of three decks in the center hull, with respective permeabilities of 0.6, 0.7, and 0.8, for net useable center-deck RORO storage areas of approximately 5294, 6176, and 7058 m 2 , respectively. There are approximately 2823 and 4990 m2 in each of the fore and aft upper deck quarters, respectively, with permeability of 0.9, yielding net useable areas of approximately 2541 and 4491 m 2 . The overall RORO net useable storage area is thus approximately 32,593 m 2  or, at 45 m 2 /vehicle, space for approximately 724 vehicles.  
         [0053]     Referring to Tables 2 through 6 below, Table 2 provides non-limiting details for a trimaran according to the example. Volumes, capacities, and lightship weights of the upper deck structure for the example are shown in Table 3. Table 4 provides volumes, capacities, and lightship weights of the center hull for the example. Table 5 provides volumes, capacities and lightship weights of the outrigger pontoons for the example. Table 6 provides capacities and deadweights for fluid and cargo at transit and operating drafts for the example.  
         [0054]     Nomenclature in Tables 2-6 includes the following: LS=lightship; OWL=operating waterline; P=port; PA=port aft; PF=port forward; S=starboard; SF=starboard forward; SA=starboard aft; WL=waterline. In Table 6, the unit weight for “crew and provisions” is in metric tons per person.  
                                               TABLE 2                           Example Semisubmersible Trimaran General Attributes.                Specification   Value                            Overall length, m   360               Overall breadth, m   200           Transit draft, m   14           Operating draft, m   27           Lightship weight, mt   213,000           Transit displacement, mt   335,000           Available transit deadweight, mt   122,000           Operating displacement, mt   534,000           Available operating deadweight, mt   322,000           Work deck area, m 2     52,000           Container storage space (9 m high), m 2     22,000   (2725)           (containers)           Vehicle storage space (9-12 m high), m 2     33,000   (724)           (vehicles)           Hanger space (9 m high), m 2     14,000           Other floor space in upper deck structure, m 2     112,000           Superstructure floor space, m 2     21,000           Fluid storage volume, m 3     223,000                      
 
         [0055]    
       
         
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                   
               
               
                 Example Semisubmersible Trimaran Upper Deck Structure. 
               
             
          
           
               
                   
                 Shape 
                 Length 
                 Width 
                 Depth 
                 Area 
                 Volume 
                 LS 
                 LS Wt 
               
               
                 Block 
                 factor 
                 (m) 
                 (m) 
                 (m) 
                 (m 2 ) 
                 (m 3 ) 
                 Coeff. 
                 (mt) 
               
               
                   
               
             
          
           
               
                 Center 
                 1 
                 360 
                 48.8 
                 18.3 
                 17,556 
                 321,042 
                 0.11 
                 35,315 
               
               
                 P wing 
                 1 
                 152.4 
                 75.3 
                 18.3 
                 11,472 
                 209,797 
                 0.11 
                 23,078 
               
               
                 S wing 
                 1 
                 152.4 
                 75.3 
                 18.3 
                 11,472 
                 209,797 
                 0.11 
                 23,078 
               
               
                 PF qtr 
                 0.5 
                 132.6 
                 75.3 
                 18.3 
                 4,990 
                 91,262 
                 0.11 
                 10,039 
               
               
                 SF qtr 
                 0.5 
                 132.6 
                 75.3 
                 18.3 
                 4,990 
                 91,262 
                 0.11 
                 10,039 
               
               
                 PA qtr 
                 0.5 
                 75 
                 75.3 
                 18.3 
                 2,823 
                 51,626 
                 0.11 
                 5,679 
               
               
                 SA qtr 
                 0.5 
                 75 
                 75.3 
                 18.3 
                 2,823 
                 51,626 
                 0.11 
                 5,679 
               
               
                 Superstructure 
                 1 
                 140.2 
                 30.5 
                 15.2 
                 4,273 
                 65,119 
                 0.08 
                 5,210 
               
               
                 TOTAL 
                   
                   
                   
                   
                 60,399 
                 1,091,531 
                   
                 118,117 
               
               
                   
               
             
          
         
       
     
         [0056]    
       
         
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                   
               
               
                 Example Semisubmersible Trimaran Center Hull. 
               
             
          
           
               
                   
                 Shape 
                 Length 
                 Width 
                 Depth 
                 Area 
                 Volume 
                 LS 
                 LS Wt 
               
               
                 Block 
                 factor 
                 (m) 
                 (m) 
                 (m) 
                 (m 2 ) 
                 (m 3 ) 
                 Coeff. 
                 (mt) 
               
               
                   
               
             
          
           
               
                 Above 
                 0.904 
                 320 
                 30.5 
                 25 
                 8,823 
                 220,576 
                 0.11 
                 24,263 
               
               
                 WL 
               
               
                 Chine to 
                 0.904 
                 320 
                 30.5 
                 4.9 
                 8,823 
                 43,233 
                 0.11 
                 4,756 
               
               
                 WL 
               
               
                 Chine 
                 1 
                 324.6 
                 39.7 
                 6.1 
                 12,870 
                 78,454 
                 0.12 
                 9,414 
               
               
                 Transition 
                 0.899 
                 360 
                 48.8 
                 2 
                 15,783 
                 31,565 
                 0.11 
                 3,472 
               
               
                 freeboard 
               
               
                 Transition 
                 0.805 
                 360 
                 48.8 
                 14 
                 15,783 
                 197,852 
                 0.11 
                 21,764 
               
               
                 submerged 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 TOTAL 
                   
                   
                   
                   
                 62,081 
                 571,680 
                   
                 63,669 
               
               
                   
               
             
          
         
       
     
         [0057]    
       
         
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                   
               
               
                 Example Semisubmersible Trimaran Outrigger Pontoons 
               
             
          
           
               
                   
                 Shape 
                 Length 
                 Width 
                 Depth 
                 Area 
                 Volume 
                 LS 
                   
               
               
                 Block 
                 factor 
                 (m) 
                 (m) 
                 (m) 
                 (m 2 ) 
                 (m 3 ) 
                 Coeff. 
                 LS Wt (mt) 
               
               
                   
               
             
          
           
               
                 PF column 
                 0.675 
                 45.7 
                 18.1 
                 25 
                 559 
                 13,964 
                 0.12 
                 1,676 
               
               
                 above OWL 
               
               
                 SF column 
                 0.675 
                 45.7 
                 18.1 
                 25 
                 559 
                 13,964 
                 0.12 
                 1,676 
               
               
                 above OWL 
               
               
                 PA column 
                 0.675 
                 45.7 
                 18.1 
                 25 
                 559 
                 13,964 
                 0.12 
                 1,676 
               
               
                 above OWL 
               
               
                 SA column 
                 0.675 
                 45.7 
                 18.1 
                 25 
                 559 
                 13,964 
                 0.12 
                 1,676 
               
               
                 above OWL 
               
               
                 PF column 
                 0.675 
                 45.7 
                 18.1 
                 11 
                 559 
                 6,144 
                 0.12 
                 737 
               
               
                 pontoon to 
               
               
                 OWL 
               
               
                 SF column 
                 0.675 
                 45.7 
                 18.1 
                 11 
                 559 
                 6,144 
                 0.12 
                 737 
               
               
                 pontoon to 
               
               
                 OWL 
               
               
                 PA column 
                 0.675 
                 45.7 
                 18.1 
                 11 
                 559 
                 6,144 
                 0.12 
                 737 
               
               
                 pontoon to 
               
               
                 OWL 
               
               
                 SA column 
                 0.675 
                 45.7 
                 18.1 
                 11 
                 559 
                 6,144 
                 0.12 
                 737 
               
               
                 pontoon to 
               
               
                 OWL 
               
               
                 P pontoon 
                 0.92 
                 213.3 
                 21.9 
                 2 
                 4,307 
                 8,615 
                 0.15 
                 1,292 
               
               
                 transition 
               
               
                 freeboard 
               
               
                 S pontoon 
                 0.92 
                 213.3 
                 21.9 
                 2 
                 4,307 
                 8,615 
                 0.15 
                 1,292 
               
               
                 transition 
               
               
                 freeboard 
               
               
                 P pontoon 
                 0.855 
                 213.3 
                 21.9 
                 14 
                 4,003 
                 56,042 
                 0.15 
                 8,406 
               
               
                 S pontoon 
                 0.855 
                 213.3 
                 21.9 
                 14 
                 4,003 
                 56,042 
                 0.15 
                 8,406 
               
               
                 TOTAL 
                   
                   
                   
                   
                 21,092 
                 209,746 
                   
                 29,048 
               
               
                   
               
             
          
         
       
     
         [0058]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                   
               
               
                 Example Semisubmersible Trimaran Representative Deadweights 
               
             
          
           
               
                   
                 At Transit Draft 
                 At Operating Draft 
               
             
          
           
               
                 Item 
                 Unit Wt 
                 Qty. 
                 Weight 
                 Qty. 
                 Weight 
               
               
                   
               
               
                 Bulk Fluids 
                 (mt/m 3 ) 
                 (m 3 ) 
                 (mt) 
                 (m 3 ) 
                 (mt) 
               
               
                   
               
               
                 Potable Water 
                 1 
                 22,000 
                 22,000 
                 22,000 
                 22,000 
               
               
                 Fuel 
                 0.8 
                 25,000 
                 20,000 
                 30,000 
                 24,000 
               
               
                 Diesel for Vehicles 
                 0.75 
                 20,000 
                 15,000 
                 20,000 
                 15,000 
               
               
                 Aviation fuel 
                 0.65 
                 22,000 
                 14,300 
                 22,000 
                 14,300 
               
               
                 Lube/Hydraulic Oil 
                 0.93 
                 1,000 
                 930 
                 1,000 
                 930 
               
               
                 Ballast 
                 1.025 
                 27,598 
                 28,288 
                 119,339 
                 122,322 
               
               
                   
               
               
                 Cargo 
                 (mt) 
                 (each) 
                 (mt) 
                 (each) 
                 (mt) 
               
               
                   
               
               
                 Containers 
                 27.5 
                 575 
                 15,812.5 
                 2,725 
                 74,937.5 
               
               
                 Tanks, heavy 
                 70 
                 0 
                 0 
                 150 
                 10,500 
               
               
                 vehicles 
               
               
                 Trucks/vehicles 
                 12 
                 0 
                 0 
                 570 
                 6,840 
               
               
                 Aircraft 
                 6 
                 0 
                 0 
                 200 
                 1,200 
               
               
                 Crew and provisions 
                 0.5 
                 1,000 
                 500 
                 10,000 
                 5,000 
               
               
                 Supplies, misc. 
                   
                   
                 5,000 
                   
                 20,000 
               
               
                 Total Deadweight 
                 (mt) 
                   
                 121,831 
                   
                 317,029.5 
               
             
          
           
               
                 Allowable 
                   
                 106,851 
                 306,785 
               
               
                 Deadweight 
               
               
                 Ballast Required 
                   
                 −14,979 
                 −10,244 
               
               
                 Container Space 
                   
                  4,700 m 2   
                  22,276 m 2   
               
               
                 Required 
               
               
                 Container Space 
                   
                  22,406 m 2   
                  22,406 m 2   
               
               
                 Available 
               
               
                 Cargo Fluids on 
                   
                 23.8 million gallons 
                 25.1 million gallons 
               
               
                 Board 
               
               
                 Fluid Space 
                   
                  90,093 m 3   
                  95,013 m 3   
               
               
                 Required 
               
               
                 Fluid Space 
                   
                 223,167 m 3   
                 223,167 m 3   
               
               
                 Available 
               
               
                 Number of Vehicles 
                   
                 0 
                 720 
               
               
                 Vehicle Capacity 
                   
                 724 
                 724 
               
               
                   
               
             
          
         
       
     
         [0059]     The invention is described above with reference to non-limiting examples provided for illustrative and explanatory purposes only. Various modifications and changes will become apparent to the skilled artisan in view thereof. It is intended that all such changes and modifications are within the scope and spirit of the appended claims and embraced thereby.