Sailboard with slotted winglets

Abstract

A winglet in a planing hull for sailboards with longitudinal length at least three times its transverse width, or a top slot that covers at least half the winglet area, and a forward slot and or a top slot, which allows dynamic lift from both the top and bottom surface of the winglet when the board is traveling at a transition speed between displacement mode and planing mode, but at high planing speed it does not normally have lift from the top surface of the winglet. This winglet may have a camber/slope step on the planing surface. In addition the transverse section of the nose of the hull can have the shape of an upside down wing.

1 . A sailboard hull comprising
 at least one set of winglets, whose length is at least 3 times the winglet width, with a forward slot in the front of said winglet and/or a slot on top of said winglet, and   a bottom surface in front of said forward slot, which acts as a planing surface and wherein said forward or top slots allows the winglet to have lift both on the top and bottom of said winglet when the board is transitioning from displacement mode to planing mode.   
     
     
         2 . The sailboard hull as recited in  claim 1 , wherein said forward slot is mostly covered on the top of the said slot to reduce the spray behind the said slot, from the nose of the winglet. 
     
     
         3 . The sailboard hull as recited in  claim 1 , wherein said winglets are configured as hydrofoils near the front or middle of the hull. 
     
     
         4 . The sailboard hull as recited in  claim 2 , wherein said forward slot is near the maximum pressure location on the bottom edge of the said hull or roughly 1/10 th  of the wetted length back from the front of the wetted length when the sailboard is in transition from a displacement mode to a planing mode. 
     
     
         5 . The sailboard hull as recited in  claim 2 , wherein said slot is partially covered on the outer edge. 
     
     
         6 . The sailboard hull as recited in  claim 2 , wherein the front of said winglet is swept back between 25° and 45°. 
     
     
         7 . The sailboard hull as recited in  claim 1  wherein the bottom surface of said winglet has at least one camber/slope step. 
     
     
         8 . The sailboard hull as recited in  claim 7  wherein a nose of said hull is shaped like an upside down wing. 
     
     
         9 . The sailboard hull as recited in  claim 7  wherein said sailboard hull further includes a fin and a surface in front of said step is below that of the center of the board in the region of the said step, such that the region near said fin is roughly, flat within 5 mm. 
     
     
         10 . The sailboard hull as recited in  claim 7  wherein said winglet is a main winglet and has an auxiliary winglet in front of said main winglet. 
     
     
         11 . The sailboard hull as recited in  claim 10  wherein a front of a bottom surface of said main and auxiliary winglets is above the bottom of said sailboard hull. 
     
     
         12 . The sailboard hull as recited in  claim 7  wherein the said step has a camber depth in the range of 0.5 to 4 cm. 
     
     
         13 . A sailboard hull comprising at least one set of winglets in the shape of a hydrofoil, with a top slot, which covers at least half of the said winglets. 
     
     
         14 . The sailboard hull as recited in  claim 13 , which further includes a camber/slope step. 
     
     
         15 . A sailboard hull having a winglet and surface forming a front slot above said winglet wherein, in a displacement or transitional mode, said surface causes water flow over a top surface of said winglet to produce Coanda lift and wherein, in a planing mode, a bottom of said winglet provides a planing surface. 
     
     
         16 . The sailboard hull as recited in  claim 15  further comprising a top slot. 
     
     
         17 . The sailboard hull as recited in  claim 16  wherein said top slot includes a support vane. 
     
     
         18 . The sailboard hull as recited in  claim 15  wherein said front slot is partially covered. 
     
     
         19 . The sailboard hull as recited in  claim 15  wherein said surface is located near the maximum pressure location on the bottom edge of said hull or roughly 1/10 th  of the wetted length back from the front of the wetted length when the sailboard is in transition from a displacement mode to a planing mode. 
     
     
         20 . The sailboard hull as recited in  claim 15  wherein said surface is provided on an auxiliary winglet. 
     
     
         21 . A sailboard hull having a winglet configured such that, in a displacement or transitional mode, said surface causes water flow over a top surface of said winglet to produce lift and wherein, in a planing mode, a bottom surface of said winglet provides a planing surface. 
     
     
         22 . A sailboard hull as recited in  claim 21 , wherein said winglet extends below a bottom surface region of said sailboard hull adjacent to or in front of a fin. 
     
     
         23 . A sailboard hull as recited in  claim 21 , wherein a bottom surface region of said sailboard hull adjacent to or in front of a fin has a concave or “Vee” shape. 
     
     
         24 . A sailboard hull as recited in  claim 21 , further including a further winglet configured such that, in displacement or transitional mode, said surface causes water flow over a top surface of said winglet to produce lift and wherein, in a planing mode, a bottom surface of said winglet provides a planing; surface. 
     
     
         25 . A sailboard hull as recited in  claim 24 , wherein winglet and said further winglet are located to form a slot between them.