Hydrofoil boat

Abstract

A hydrofoil boat (100), having a “T” foil comprising an underwater mast (41) and an elongated horizontal hydrofoil (47) The draft and underwater beam of the boat can be reduced by sliding the mast upwards and rotating the hydrofoil from the normal transverse orientation to a fore-and-aft direction.

1 . Watercraft ( 100 ), having an underwater appendage comprising an underwater mast ( 41 ) and an elongated hydrofoil ( 47 ) centrally connected to the lower end of the mast ( 41 ), wherein the hydrofoil is oriented transversally in a first configuration to generate lift, characterized in that the hydrofoil ( 47 ) is rotatable about a vertical axis such that the hydrofoil ( 47 ) can be turned towards a longitudinal plane (L) of the watercraft ( 100 ) in a second configuration. 
     
     
         2 . The watercraft of  claim 1 , wherein the underwater mast ( 41 ) can be caused to slide upwards such that, in the first configuration, the hydrofoil ( 47 ) is separated from a hull ( 10 ) of the watercraft, and, in the second configuration, the hydrofoil ( 47 ) is closer to the hull ( 10 ) than in the first configuration. 
     
     
         3 . The watercraft of  claim 1 or 2  wherein a width (w) of the hydrofoil ( 47 ) exceeds a maximum beam (b) of the hull ( 10 ). 
     
     
         4 . The watercraft of  any one of the preceding claims , wherein the hydrofoil ( 47 ) and the underwater mast ( 41 ) are connected rigidly. 
     
     
         5 . The watercraft of any one of the  claims 2 to 4 , wherein the underwater mast ( 41 ) is slidable inside a hollow post ( 49 ) above the waterline. 
     
     
         6 . The watercraft of  any one of the preceding claims , wherein the hydrofoil ( 47 ) has control surfaces ( 48 ) whose inclination can be set by a control system. 
     
     
         7 . The watercraft of  any one of the preceding claims , further comprising, abaft the underwater appendage, a rudder ( 51 ) having an underwater horizontal stabilizer ( 57 ), wherein the rudder is slidable vertically to reduce a draft of the watercraft. 
     
     
         8 . The watercraft of  any one of the preceding claims , wherein the underwater appendage and/or the rudder have a propulsion pod ( 43 ,  53 ) comprising an electric motor and a propeller ( 45 ,  55 ). 
     
     
         9 . The watercraft of  claims 4 and 5 , wherein the horizontal stabilizer ( 57 ) has additional control surfaces ( 58 ) whose inclination can be set by the control system. 
     
     
         10 . The watercraft of  any one of the preceding claims , wherein the hydrofoil ( 47 ) is aligned with the longitudinal plane (L) of the watercraft in the second configuration, and a total angle of rotation of the hydrofoil ( 47 ) between the first configuration and the second configuration is essentially 90°. 
     
     
         11 . The watercraft of  any one of the preceding claims , wherein the hull has a longitudinal tunnel ( 11 ) and the hydrofoil ( 47 ) enters in the tunnel ( 11 ) in the second configuration.