fin questions (NOT waveski related)

has anyone used pro tecks? like/dislike? what is the fastest fin setup? fish/thruster/single. (fish setup on a fish board, etc.) does anyone make fin blanks? like just a pre made chunk of fiberglass that can be shaped, with no attatchment stuff? thanks in advance… ps. anyone here live on maui and wanna let a newbie watch them shape/etc?

The fastest setup is no fins. A large issue has always been minimizing drag while maximizing control. Control won. Thrusters are slower than singlefins, twinfins, or twinzers, but are the fin choice of most because they allow you to turn better. You can make your own fiberglass fins by layering glass and resin.

Fast fins have the smallest area to minimize skin friction, and are thinnest to minimize form and frontal area. Ergo, the smallest single fin you can still control. Of course, there are a LOT of other issues involved. One quick way to make a fin that’s cheap and relatively painless is to use three layers of mat with a layer of 1/8 inch mahogany ply on either side. It’s easy to grind the foil, not so itchy, easy on the tool since you’re mostly cutting wood; and if you get the grain of the plies right it looks nice. AND, it’s lighter than a all-glass fin. AND, the glass up the center ends up on the leading and trailing edges (stronger than wood at that point). AND whether or not you drop in a little color, there’s a nice halo around the wood. go to it! I’m in Honolulu.

Fast fins are not all about wetted area. There is also angle of attack, length, and foiling. Longer fins have better lift:drag ratios. This occurs because the uneven pressures from an attacking fin cause eddies around the fin tip. The eddy size stays the same as the fin gets longer, so longer fins have the same drag from the tip eddies as short fins, but get increasing drive from an increased length. Foiling is curvature along the fin. Think of a sailboat tacking into the wind. Its sail is well-foiled, concave on the high pressure side, and convex on the low pressure side. On thrusters there is a trend for outside fins to be more convex on the outside - the low pressure side when that fin is on the inside of a turn. Angle of attack also relates to drag. A fin aligned with the board direction of motion has minimized drag - the more the angle of attack, the higher the drag. In particular, side fins on a thruster are angled in (or toed in). This angling also creates drag. But, it is critical to allowing a thruster to turn well and create drive in rail-to-rail transitions.