following a recent thread,ive decided to make my own fins.
the proposed construction is as follows:
Core of plywood,2 or 3 lams of 4oz either side of this,foam outers with a single lam of 4oz.
max achievable thickness with 1 thickness of foam either side of ply core = 1/2 inch.
is this too thick?
the finset will be for a thruster,full foil…thats all i can think of for the moment.
First, let me tell you that a wood core will result in leading and trailing edges of wood, which will be very susceptible to dings as/when you nick a rock. Then water gets in and the wood rots and turns black.
My composite (wood/glass) glass-on fins start with at least 3 layers of 1.5 ounce mat and some 3-ply mahogany packing case material on either side. Resultant max thickness is usually 3/8" but it could easily be more. Several advantages, including lightness, easy foiling, less nasty dust, and cheap to make. They are plenty stiff and with the glass on the leading edge they are ding resistant.
My current project, a 9’8" x 22" x 3-1/4" longboard for a 180-lb customer, will have a solid koa fin. It will need a substantial glass rope halo at the leading edge, to survive what I think he will do to it. The trailing edge will be okay as long as I don’t make it too thin.
I don’t think we’ll see fins thicker than 1/2 inch again; I recall that years ago they were available to nearly 3/4 inch thickness. Maybe those thick fins wouldn’t lose laminar flow and stall, but they surely had to have paid a heavy price in drag.
i presume you are talking fins for trad boxes?
i hadnt realy thought about the ding thing as most of the time i surf beaches apposed to reefs.
i can see that too thick can create too much drag hence loss of speed,experiance of aerodynamics(aeromodeling,model race planes/sailplanes) has taught me that sometimes you can achive more with more rather than less,ie: a racer with a 4% section wing IS slower than say an 8% section because you have to fly the thin wing at a greater AOA…
im also gonna try fins with a ply base but spar like projections that glue into foam,pressed on glass/resin.
any thoughts on that.
reson for all this…its cheaper than buying fcs and its fun to speriment.