to Tom@daum : Thick Fins?

Forgive my simplicity, but from your post below, are you saying that because the speed of the water will be slower around the fins compared to the speed of the water traveling down the bottom of the board, that this will create turbulance and drag. This is true for all fins, just at a greater degree with a thicker fin? I am just trying to get a general understanding of this. I finished my fins for my fish this weekend, and all this talk of thick fins and drag has got my a little worried. I did a set of twin fins, based on some info from Magic Man (much, much, thanks). The base is 7.25 “x 5” tall. I did them out of 9mm plywood, and they came out looking good, and are light. I based the foil on a set of glass twin fins I had that were smaller (4.75 base x 5" with more rake), taking into account the difference in outer surface area. Do you think that these will be too thick? I want drive, not drag.

mike, I am not sure how thick you went with your fins. However, since the cord length is so long the rate of curvature for even a .4" thick fin could be made very shallow. On top of that, a fish type board is usually intended for use in waves that you wish to generate speed. Now we get back to Rich’s article on Swimming and Flying. You pump a fish in a path that assymilates the sinusodial path inorder to generate speed. Finer foils are typically used in waves where the rider is attempting to control his speed rather than generate speed. The wave provides sufficient power that rocker, fin template and tail volume are all used to weight back and stall or trim forward and fly. No pumping required.