Active bow foil for ship motion control

Abstract

A bow foil stabilizer system is provided where the foil is configured to be mounted relatively close to the vessel hull, preferably less than three times a maximum thickness below the keel of the vessel in the area the foil is mounted to, more preferably the foil is mounted in a recess of the vessel, which recess is in the keel of the vessel. In certain embodiments, a lowest point of the foil is approximately level with the extended keel line and a control flap of the foil is configured to rotate at least partially into a recess of the vessel in the keel area. In further aspects, the foil is mounted with a chord thereof at an angle relative to the running trim of the vessel.

What is claimed is: 
     
         1 . A stabilizer foil for a vessel comprising:
 a foil which is configured to articulate based on one or more control inputs to generate a control force, the foil having a lower surface, an upper surface and a maximum foil thickness;   the foil is configured to attach to the vessel in a fixed position such that a lowest point of the lower surface is positioned less than three times the maximum thickness below a keel of the vessel in an area adjacent to the foil.   
     
     
         2 . The stabilizer foil of  claim 1  wherein the lowest point is positioned less than three times the maximum thickness above the keel of the vessel in the area adjacent the foil. 
     
     
         3 . The stabilizer foil of  claim 1  wherein the foil is configured to be mounted in the fixed position at least partially in a recess of the hull, the recess located in a forward portion of the vessel. 
     
     
         4 . The stabilizer foil of  claim 3  wherein the recess is in the keel and the lowest point of the lower surface is even with an extended keel line at the recess and a flap of the foil is configured to rotate at least partially into the recess. 
     
     
         5 . The stabilizer foil of  claim 1  wherein the foil includes a mounting area comprising holes therethrough and bolts are configured to pass through the holes and into holes in keel support structure of the vessel. 
     
     
         6 . The stabilizer of  claim 1  wherein the foil articulates by a flap of the foil rotating to generate the control force. 
     
     
         7 . The stabilizer of  claim 1  wherein port and starboard sides of the foil share a common center plane. 
     
     
         8 . A stabilizer foil for a vessel comprising:
 a foil having a flap which is configured to articulate relative to the foil based on one or more control inputs;   the foil configured to mount to a bow area of the vessel in a fixed position such that a chord line of the foil is positioned at a non-zero angle relative to a running trim of the vessel.   
     
     
         9 . The stabilizer foil of  claim 8  wherein the non-zero angle is at least 3 degrees. 
     
     
         10 . The stabilizer foil of  claim 8  wherein the foil has a substantially symmetrical cross section. 
     
     
         11 . The stabilizer of  claim 8  wherein port and starboard sides of the foil share a common center plane. 
     
     
         12 . The stabilizer of  claim 8  wherein the foil is configured to attach to the vessel such that a lowest point of a lower surface of the foil is positioned less than three times the maximum thickness below a keel of the vessel in an area adjacent to the foil. 
     
     
         13 . The stabilizer foil of  claim 12  wherein the lowest point is positioned less than three times the maximum thickness above the keel of the vessel in the area adjacent the foil. 
     
     
         14 . The stabilizer foil of  claim 8  wherein the running trim is determined based on a predefined speed and weight distribution in ideal conditions. 
     
     
         15 . A stabilizer foil for a vessel comprising:
 a foil system mounted in a bow area of the vessel and including foil sections which extend outwards on port and starboard sides of the vessel and the foil sections have a maximum foil thickness;   the vessel comprising a lowest point of the vessel which lowest point of the vessel is a point on the vessel other than on the foil sections;   a lowest point of the foil sections is no more than three times the maximum foil thickness below the lowest point of the vessel.   
     
     
         16 . The stabilizer foil of  claim 15  wherein the lowest point of the foil sections is at or above the lowest point of the vessel. 
     
     
         17 . The stabilizer of  claim 15  wherein foil sections of the foil system share a common center plane. 
     
     
         18 . The stabilizer of  claim 15  wherein a highest point of the foil sections is no more than three times the maximum foil thickness above a lowest point of a keel of the vessel. 
     
     
         19 . The stabilizer of  claim 18  wherein foil sections of the foil system share a common center plane. 
     
     
         20 . The stabilizer of  claim 1  wherein the foil includes a flap which is articulated based on one or more control inputs to cause the flap to rotate to generate a control force.