Hydrofoil module and marine vessel

Abstract

A hydrofoil apparatus includes a pair of hydrofoil modules each including a clamp bracket, a swivel bracket, a wing including a hydrofoil, and a rotation actuator. In a reference state in which angles of attack of the hydrofoils of the pair of hydrofoil modules are the same as each other, a first rotation shaft is located forward of a center of an area of the hydrofoil.

What is claimed is: 
     
         1 . A hydrofoil apparatus comprising:
 a pair of hydrofoil modules each including:
 a clamp bracket including a first rotation shaft having a first rotation center axis extending in a right-left direction and removably attached to a hull; 
 a swivel bracket rotatably attached to the clamp bracket via the first rotation shaft; 
 a wing including a hydrofoil and a strut including a lower end on which the hydrofoil is provided and an upper end attached to the swivel bracket; and 
 a rotation actuator to rotate the wing together with the swivel bracket in a forward-rearward direction around the first rotation center axis to change an angle of attack of the hydrofoil; wherein 
   the pair of hydrofoil modules are configured to provide the hull with a lift force during sailing to raise the hull; and   in a reference state in which angles of attack of the hydrofoils of the pair of hydrofoil modules are same as each other, the first rotation shaft is located forward of a center of an area of the hydrofoil.   
     
     
         2 . The hydrofoil apparatus according to  claim 1 , wherein in the reference state, the first rotation shaft is located forward of the center of the area of the hydrofoil and rearward of a leading edge of the hydrofoil. 
     
     
         3 . The hydrofoil apparatus according to  claim 1 , wherein the clamp bracket includes a bolt hole through which a bolt is able pass to fix the clamp bracket to the hull, and is removably fixed to the hull by the bolt passing through the bolt hole. 
     
     
         4 . The hydrofoil apparatus according to  claim 1 , wherein a reference angle of attack, which is the angle of attack of the hydrofoil in the reference state, is set to a predetermined angle of about 4 degrees or more and about 8 degrees or less. 
     
     
         5 . The hydrofoil apparatus according to  claim 4 , wherein an initial angle of attack, which is the angle of attack of the hydrofoil in a state in which the strut extends in a vertical direction, is greater than 0 degrees and less than the reference angle of attack. 
     
     
         6 . The hydrofoil apparatus according to  claim 1 , wherein in the reference state, the strut is inclined such that the lower end is located forward of the upper end, and extends in a direction along a line of action of a resultant force of a lift force and a drag force acting on the hydrofoil. 
     
     
         7 . The hydrofoil apparatus according to  claim 1 , wherein
 the swivel bracket includes a second rotation shaft having a second rotation center axis extending in the forward-rearward direction, and is configured to support the wing via the second rotation shaft such that the wing is rotatable; and   the wing is configured to rotate around the second rotation center axis to switch between an underwater position at which the hydrofoil is located underwater, and an above-water position at which the hydrofoil is located above the water.   
     
     
         8 . The hydrofoil apparatus according to  claim 1 , wherein
 the rotation actuator includes a hydraulic cylinder to press the swivel bracket by extending and retracting to rotate the swivel bracket around the first rotation center axis; and   the hydraulic cylinder includes a first end attached to the clamp bracket, and a second end attached to the swivel bracket.   
     
     
         9 . The hydrofoil apparatus according to  claim 8 , further comprising:
 a hydraulic oil feeder attached to the clamp bracket and including a pump to supply hydraulic oil to the hydraulic cylinder and a motor to drive the pump.   
     
     
         10 . The hydrofoil apparatus according to  claim 9 , wherein the hydraulic cylinder and the hydraulic oil feeder are located side by side in the right-left direction, and are located rearward of the first rotation shaft. 
     
     
         11 . The hydrofoil apparatus according to  claim 10 , wherein
 the second end of the hydraulic cylinder is located forward of the first end of the hydraulic cylinder and above the first rotation shaft; and   the hydraulic cylinder is configured to extend a rod to rotate the wing rearward and decrease the angle of attack, and to retract the rod to rotate the wing forward and increase the angle of attack.   
     
     
         12 . The hydrofoil apparatus according to  claim 1 , wherein in the reference state, the first rotation shaft is located on a line of action of a resultant force of a lift force and a drag force acting on the hydrofoil as viewed in the right-left direction. 
     
     
         13 . The hydrofoil apparatus according to  claim 1 , wherein in the reference state, the first rotation center axis of the first rotation shaft is located forward of a line of action of a resultant force of a lift force and a drag force acting on the hydrofoil. 
     
     
         14 . A marine vessel comprising:
 a hull; and   a pair of hydrofoil modules on the hull and each including:
 a clamp bracket including a first rotation shaft having a first rotation center axis extending in a right-left direction and removably attached to the hull; 
 a swivel bracket rotatably attached to the clamp bracket via the first rotation shaft; 
 a wing including a hydrofoil and a strut including a lower end on which the hydrofoil is provided and an upper end attached to the swivel bracket; and 
 a rotation actuator to rotate the wing together with the swivel bracket in a forward-rearward direction around the first rotation center axis to change an angle of attack of the hydrofoil; wherein 
   the pair of hydrofoil modules are configured to provide the hull with a lift force during sailing to raise the hull; and   in a reference state in which angles of attack of the hydrofoils of the pair of hydrofoil modules are same as each other, the first rotation shaft is located forward of a center of an area of the hydrofoil.   
     
     
         15 . The marine vessel according to  claim 14 , wherein in the reference state, the first rotation shaft is located forward of a center of the area of the hydrofoil and rearward of a leading edge of the hydrofoil. 
     
     
         16 . The marine vessel according to  claim 14 , wherein the clamp bracket includes a bolt hole through which a bolt is able to pass to fix the clamp bracket to the hull, and is removably fixed to the hull by the bolt passing through the bolt hole. 
     
     
         17 . The marine vessel according to  claim 14 , wherein a reference angle of attack, which is the angle of attack of the hydrofoil in the reference state, is set to a predetermined angle of about 4 degrees or more and about 8 degrees or less. 
     
     
         18 . The marine vessel according to  claim 17 , wherein an initial angle of attack, which is the angle of attack of the hydrofoil in a state in which the strut extends in a vertical direction, is greater than 0 degrees and less than the reference angle of attack. 
     
     
         19 . The marine vessel according to  claim 14 , wherein in the reference state, the strut is inclined such that the lower end is located forward of the upper end, and extends in a direction along a line of action of a resultant force of a lift force and a drag force acting on the hydrofoil. 
     
     
         20 . The marine vessel according to  claim 14 , wherein
 the swivel bracket includes a second rotation shaft having a second rotation center axis extending in the forward-rearward direction, and is configured to support the wing via the second rotation shaft such that the wing is rotatable; and   the wing is configured to rotate around the second rotation center axis to switch between an underwater position at which the hydrofoil is located underwater, and an above-water position at which the hydrofoil is located above the water.