Pleasure craft

Abstract

The present invention relates to a craft comprising a surface module, a single submerged body and a one strut for connecting the body to the module, wherein said strut is operative for moving the submerged body relative to the surface module from a extended position of the body in which the surface module is arranged in vertically spaced relation thereabove to a retracted position in which the submerged body and the surface module together form a displacement hull, wherein the hull of the surface module comprises a hollow recess for receiving the submerged body in the retracted position, wherein the recess and the upper part of the submerged body have a mating form such that the hull of the craft in the retracted position of the submerged body has a drag reducing form.

1 . Craft comprising a surface module, a single submerged body and a one strut for connecting the body to the module, wherein said strut is operative for moving the submerged body relative to the surface module from a extended position of the body in which the surface module is arranged in vertically spaced relation thereabove to a retracted position in which the submerged body and the surface module together form a displacement hull, characterized in that the hull of the surface module comprises a hollow recess for receiving the submerged body in the retracted position, wherein the recess and the upper part of the submerged body have a mating form such that the hull of the craft in the retracted position of the submerged body has a drag reducing form.  
     
     
         2 . Craft according to  claim 1 , wherein a propeller is mounted to the submerged body and wherein the recess in the surface module is further recessed at the aft section thereof for receiving the propeller in the retracted position of the submerged body.  
     
     
         3 . Craft according to  claim 2 , wherein strakes are arranged along the edges of the further recess in the hull.  
     
     
         4 . Craft according to one of the preceding claims, wherein a rudder is attached to the surface module, said rudder being located in the wake of the propeller in the retracted position of the submerged body.  
     
     
         5 . Craft according to one of the preceding claims, wherein the submerged body has a raised bow and a streamlined shape with a flattened circular cross-section being axi-symmetrical at the stern.  
     
     
         6 . Craft according to one of the preceding claims, wherein the submerged body comprises at least two pairs of hydrofoils being mounted to the submerged body along the length thereof, the hydrofoils of each pair lying on both sides of the submerged body.  
     
     
         7 . Craft according to  claim 6 , wherein the place of attachment of each hydrofoil on the submerged body is determined dependent on the pressure distribution generated by water flow along the submerged body in extended position and/or vortex generation around the hydrofoils.  
     
     
         8 . Craft according to  claim 6  or  7 , wherein a winglet is fitted to the tip of at least the aft pair of hydrofoils.  
     
     
         9 . Craft according to one of the claims  6 - 9 , wherein the hydrofoils of each pair are placed in a negative dihedral.  
     
     
         10 . Craft according to one of the claims  6 - 9 , wherein each hydrofoil is rotatable around its longitudinal axis.  
     
     
         11 . Craft according to one of the preceding claims, wherein the bow section of the submerged body plastically deforms when hitting a obstacle.  
     
     
         12 . Craft according to  claim 11 , wherein the bow section is provided with a tank filled with water and bounded with a nozzle shaped closure which opens at a predetermined pressure in the tank.  
     
     
         13 . Craft according to one of the claims, wherein the connection between the strut on the one side and the submerged body and/or the surface module on the other side fails at a predetermined impact level upon hitting an obstacle.  
     
     
         14 . Craft according to one of the claims  6 - 13 , further comprising a control unit for controlling the rotation of each hydrofoil.  
     
     
         15 . Craft according to  claim 14 , further comprising xyz roll rate sensors for providing xyz roll rate information of the craft.  
     
     
         16 . Craft according to  claim 15 , further comprising a GPS for providing Lat/Long, attitude and directional information of the craft.  
     
     
         17 . Craft according to  claim 16 , wherein the xyz roll rate information is used as input signal and the GPS information is used as reference signal of the control unit.  
     
     
         18 . Craft according to  claim 16 , wherein the xyz roll rate information is used as input signal of a rate input controller and wherein the GPS information is used as input signal of an attitude input controller, said controllers providing dual redundant input signals for the control unit.  
     
     
         19 . Craft according to  claim 18 , wherein the control unit averages the input signals of the controllers for controlling the angles of the hydrofoils between safety constraints.  
     
     
         20 . Craft according to  claim 19 , wherein the control unit comprises an actuator for each hydrofoil.  
     
     
         21 . Craft according to  claim 20 , wherein the hydrofoil actuators each comprise separate control and actuating elements supplied from separate power sources integrated into a single unit.