Vessel provided with a foil situated below the waterline

Abstract

Non-planing vessel with single hull ( 2 ). A foil ( 10 ) is fitted below the waterline at the place where the greatest flow constriction exists, in other words at the transition from the relatively broad part ( 9 ) to the narrowing part. This foil is situated at a distance from the hull ( 2 ) and preferably extends horizontally over as large a part of the hull as possible at a constant distance from the latter. The foil is designed in such a way that, apart from a lifting force, a forward propelling force is exerted. The performance of the vessel can be improved by fitting such a foil.

1 . Vessel ( 1 ) with a single hull ( 2 ), the aft part ( 4 ) of which has a smaller water displacement and less breadth lying in the water than the middle part ( 7 ), and provided with a foil ( 10 ) extending below the waterline, characterized in that said foil ( 10 ) extends substantially transversely to the longitudinal axis ( 8 ) of said vessel, at the position of the greatest flow constriction of said vessel caused by said reducing water displacement, lying at a distance (a) below the hull over a breadth (b) comprising at least half the breadth of said hull at the position of the greatest flow constriction of said vessel caused by said reducing water displacement.  
     
     
         2 . Vessel according to  claim 1 , in which the distance of said foil from said hull is substantially constant over the entire breadth.  
     
     
         3 . Vessel according to one of the preceding claims, in which said foil extends to the waterline ( 6 ).  
     
     
         4 . Vessel according to one of the preceding claims, in which the position of said foil relative to said hull is fixed.  
     
     
         5 . Vessel according to one of the preceding claims, in which the length (L) of said foil is at least 50% of the distance (a) of said foil from the hull.  
     
     
         6 . Vessel according to one of the preceding claims, in which the length of said foil decreases in the outward direction from the longitudinal axis (L 1 ).  
     
     
         7 . Vessel according to one of the preceding claims, in which said foil is designed in such a way that during the forward movement of the vessel it exerts a forward propulsion force on said vessel.