All this effort expended trying to re-invent the wheel - again......
High-speed surfacing rudders are wedge-shaped because that causes the least amount of drag. The water off each side of the rudder stays apart - you do not want it to come back together too soon. Air travels down the back face of the rudder to fill the void left behind the blade - this requires much less energy than trying to move water to fill the void because air weighs less and moves around turns much more easily. More energy wasted means more drag and lower speeds.
Sharp, airfoil-shaped training edges are terrible, promoting occilations of the rudder and resulting in wandering on the straights. Wedge shaped rudders promote better turning like wedge-shaped prop blades do, creating low pressure on the turning edge to help bring the transom around. This is all well-proven technology in both full-scale and model applications.
You simply cannot apply the technology from slow-moving displacement sailboats to surface-planing racing powerboats. The rudders are different (as is the surface finish of the boat bottom. Furniture wax is certainly not where it's at for a "speed coat.")
Believe me, if airfoil-shaped rudders were better, the Budweiser Unlimited team would have used that technology. But they used wedge-shaped rudders and turnfins. They didn't wax the bottom of their boats either. While thinking outside the box is good for some things, others based on basic physics just can't be improved. Now when we go to fuel-cell technology and race at 150 mph we may have to do some things differently - but I bet it won't include airfoil-shaped rudders.
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High-speed surfacing rudders are wedge-shaped because that causes the least amount of drag. The water off each side of the rudder stays apart - you do not want it to come back together too soon. Air travels down the back face of the rudder to fill the void left behind the blade - this requires much less energy than trying to move water to fill the void because air weighs less and moves around turns much more easily. More energy wasted means more drag and lower speeds.
Sharp, airfoil-shaped training edges are terrible, promoting occilations of the rudder and resulting in wandering on the straights. Wedge shaped rudders promote better turning like wedge-shaped prop blades do, creating low pressure on the turning edge to help bring the transom around. This is all well-proven technology in both full-scale and model applications.
You simply cannot apply the technology from slow-moving displacement sailboats to surface-planing racing powerboats. The rudders are different (as is the surface finish of the boat bottom. Furniture wax is certainly not where it's at for a "speed coat.")
Believe me, if airfoil-shaped rudders were better, the Budweiser Unlimited team would have used that technology. But they used wedge-shaped rudders and turnfins. They didn't wax the bottom of their boats either. While thinking outside the box is good for some things, others based on basic physics just can't be improved. Now when we go to fuel-cell technology and race at 150 mph we may have to do some things differently - but I bet it won't include airfoil-shaped rudders.
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