Towable buoy

Abstract

A towable buoy having a tow point for connection to a tow cable of a vessel, wherein the position of the tow point is translationally moveable with respect to the remainder of the buoy. Also, a method of operating the towable buoy.

1 . A towable buoy comprising a tow point for connection to a tow cable of a vessel, wherein the position of the tow point is translationally moveable with respect to the remainder of the buoy. 
     
     
         2 . A towable buoy according to  claim 1 , wherein the position of the tow point is moveable in a fore/aft direction and/or vertically with respect to the remainder of the buoy. 
     
     
         3 . A towable buoy according to  claim 1 , wherein the position of the tow point is selectable based upon the speed and/or depth of the towing vessel. 
     
     
         4 . A towable buoy according to  claim 1 , further comprising a passive tow point adjustment mechanism for moving the position of the tow point. 
     
     
         5 . A towable buoy according to  claim 4 , wherein the passive tow point adjustment mechanism is operable to move the position of the tow point according to loads in the tow point. 
     
     
         6 . A towable buoy according to  claim 1 , further comprising an active tow point adjustment system for moving the position of the tow point. 
     
     
         7 . A towable buoy according to  claim 1 , comprising a significant metacentric height. 
     
     
         8 . A towable buoy according to  claim 1 , further comprising means to vary the centre of mass of the buoy. 
     
     
         9 . A towable buoy according to  claim 1 , further comprising means to vary the buoyancy of the buoy. 
     
     
         10 . A towable buoy according to  claim 1 , further comprising an internal ballast tank adjustable to alter the hydrostatic characteristics of the buoy. 
     
     
         11 . A towable buoy according to  claim 1 , further comprising a keel. 
     
     
         12 . A towable buoy according to  claim 11 , wherein the keel is moveable. 
     
     
         13 . A towable buoy according to  claim 1 , further comprising a lifting hydrofoil. 
     
     
         14 . A towable buoy according to  claim 13 , wherein the hydrofoil is adjustable to alter its shape, surface area and/or pitch angle. 
     
     
         15 . A towable buoy according to  claim 1 , further comprising a control system for adjusting the hydrodynamic and/or hydrostatic characteristics of the buoy. 
     
     
         16 . A towable buoy according to  claim 15 , wherein the control system is operable to act according to the speed, depth and/or orientation of the towing vessel. 
     
     
         17 . A method of operating a towable buoy having a tow point which is translationally moveable with respect to the remainder of the buoy, the method comprising:
 towing the buoy behind a moving vessel by attaching a tow cable of the vessel to the tow point; and   adjusting the position of the tow point with respect to the remainder of the buoy.   
     
     
         18 . A method according to  claim 17 , wherein the position of the tow point is adjusted according to the speed and/or depth of the vessel. 
     
     
         19 . A method according to  claim 17 , wherein the buoy is towed submerged, preferably just beneath surface water waves.