Tri-fin placement on a Modern/Vintage Fish

I am shaping a fish for a friend. The board is a some what of a vintage shape but pulled in more.@6’-6" x 16.25 x 21 x 16. and 2.50 thick. the swallow tail is going up 3 inches from the ends…the guy I am shaping this for wants a trailer fin…what should my fin placement be,how far should the tailer fin be from the end of the stringer at the tail and how far are up are front fins placed? I am going to be using the large FCS side fins and a small trailer fin in the back…

…10.5 on the sides and 5 on the center. …I really never have liked this combo(prefer a more rounded tri set-up)but the #s I have given you are somewhat the standard for the set-up you stated.This is from the trailing edges to the tips of the tail.Herb

Herb, are these the numbers you use on your thruster fishes? Wouldn’t this cluster the fins a bit much? I hear that may cause drag. regards, Håvard

Havy, The numbers here are for the large twin fin sides w/ a tiny little center fin only! …The numbers I use for my thrusters are up a thread or three.The answer to Sylvia’s “winged fish fin placement” question. …NOW DROP AND GIVE ME TWENTY!!!oppps a military flashback I guess?Herb