I was not passing judgement of weather the boat is legal or not. I will let the measurers do that.
I understand that any surface that manages to deflect rising spray back down, by newtons laws of phyisics, is being lifted by the equal and opposite force. Rounded hull shapes do this less than flatt bottomed boats and if anything tend to deflect water sideways if at all. This is why we go for flatter aft sections on planing hull forms. I made a rudder stock for the Enterprise which has a small flange along the bottom edge. It did not continue the line of the hull but did manage to turn the wake that reached the bottom of the stock. The very small effect was not quantifiable but in theory should have been helping.
In a planing mode I suspect there is little gain with this gantry because the area of hull supporting the boat decreases as speed increases. more area is unecessary. In displacment mode, despite the step the water might be fooled into thinking that the boat is longer allowing a slightly higher hull speed. As with my rudder stock the effect may not be noticeable.
I would be interested in seeing some 'Rack Cam' footage of the wake coming of the transom and comparing this with similar footage from a boat with a smaller gantry. couple that with gps info at the same time and we should have a clear answer.
