An underwater vessel and associated system

Abstract

Disclosed is a system comprising: a first, underwater, vessel provided with a substantially flat lower surface; and a second, surface, vessel, comprising a floodable well deck arranged to receive and accommodate the first vessel.

1 . A system comprising:
 an underwater vessel provided with a substantially flat lower surface; and   a surface vessel comprising a floodable well deck arranged to receive and accommodate the underwater vessel.   
     
     
         2 . The system of  claim 1 , wherein the underwater vessel has an overall length, and the flat lower surface has a length in the range 80 to 90% of the overall length of the underwater vessel. 
     
     
         3 . The system of  claim 1 , wherein the underwater vessel has a body, and the body has a widest part, and the flat lower surface has a width in the range 20 to 30% of the widest part of the body of the underwater vessel. 
     
     
         4 . The system according to  claim 1 , wherein the underwater vessel is provided with a coupling point located towards a front of the underwater vessel to facilitate docking of the underwater vessel in the surface vessel. 
     
     
         5 . The system of  claim 4 , wherein the underwater vessel is provided with a plurality of further coupling points to tether the underwater vessel in place within the surface vessel. 
     
     
         6 . The system of  claim 1 , wherein the well deck of the surface vessel is provided with a plurality of rollers in its floor to facilitate docking of the underwater vessel. 
     
     
         7 . The system of  claim 6 , wherein the plurality of rollers are able to be locked to prevent rolling. 
     
     
         8 . The system of  claim 1 , wherein the well deck is provided with an innermost surface which is provided with a buffer region to protect both the underwater vessel and the surface vessel during a docking operation. 
     
     
         9 . A method of docking using a system, the system including an underwater vessel and a surface vessel, the underwater vessel provided with a substantially flat lower surface, and the surface vessel comprising a floodable well deck arranged to receive and accommodate the underwater vessel, the method comprising:
 flooding the well deck;   attaching a tether to the underwater vessel; and   winching the underwater vessel into the well deck of the surface vessel.   
     
     
         10 . The method of  claim 9 , wherein the winching causes the flat lower flat-surface of the underwater vessel to contact at least one roller provided in a floor of the well deck. 
     
     
         11 . The method of  claim 9 , further comprising securing a plurality of additional tethers to a plurality of coupling points on an exterior of the underwater vessel and securing the additional tethers to a plurality of anchor points in the well deck. 
     
     
         12 . The method of  claim 10 , wherein the underwater vessel has a body and an overall length, and the flat lower surface has a length in the range 80 to 90% of the overall length of the underwater vessel, and the flat lower surface has a width in the range 20 to 30% of a widest part of the body of the underwater vessel. 
     
     
         13 . The system of  claim 1 , wherein the well deck of the surface vessel is provided with a plurality of skid beams in its floor to facilitate docking of the underwater vessel. 
     
     
         14 . The system of  claim 2 , wherein the underwater vessel has a body, and the body has a widest part, and the flat lower surface has a width in the range 20 to 30% of the widest part of the body of the underwater vessel. 
     
     
         15 . A system comprising:
 an underwater vessel provided with a substantially flat lower surface, wherein the underwater vessel has a body and an overall length, and the flat lower surface has a length in the range 80 to 90% of the overall length of the underwater vessel, and the flat lower surface has a width in the range 20 to 30% of a widest part of the body of the underwater vessel;   a surface vessel comprising a floodable well deck arranged to receive and accommodate the underwater vessel; and   a tether coupled between the underwater vessel and the surface vessel.   
     
     
         16 . The system according to  claim 15 , wherein the underwater vessel is provided with a tether coupling point located towards a front of the underwater vessel to facilitate docking of the underwater vessel in the surface vessel, via the tether. 
     
     
         17 . The system of  claim 15 , wherein the well deck of the surface vessel is provided with a plurality of rollers in its floor to facilitate docking of the underwater vessel. 
     
     
         18 . The system of  claim 17 , wherein the plurality of rollers are able to be locked to prevent rolling. 
     
     
         19 . The system of  claim 15 , wherein the well deck of the surface vessel is provided with a plurality of skid beams in its floor to facilitate docking of the underwater vessel. 
     
     
         20 . The system of  claim 15 , comprising a winch, wherein the well deck is provided with an innermost wall which is provided with a cushioned or deformable buffer region to protect the underwater vessel during a docking operation, wherein the tether protrudes through the buffer region and the winch is located behind the buffer region.