I have a fin that is whistling dixie. I realise that this is from the fin vibrating in the box. Whats the best way to make it fit a bit more of a snug fit?
David does your select have a 5mm back paint strip around the trailing edge. Its a built up of paint that cause the fin to whistle Im not sure why select do it must be part of the finish process. I find if you use some 1200 wet and dry on the trailing edge whistling gone. ta vando
Hi Katapult , It actually has nothing to do with the fit in the box , it's most likely due to the trailing edge of the fin being a bit thick . Can I suggest you get some 400 wet and dry sand paper on a flat block and run it along the trailing edge at about 45 deg . Like puting a small chamfer on the trailing edge . It shouldn't need much , just a few passes . What you are trying to do is thin the trailing edge down so that it,s almost sharp . Not razor sharp though ,as you are likely to lose a toe when water starting . Give it a shot , I can almost guarranty it will fix the whistle .
I agree with last to posters, I'm sure a wet and dry touch up will fix it. Try and keep the last third of the fin straight. In theory the whistle is turbulence and slows you down
Hi all, it is a standard practice of mine to sand the trailing edge of Select fins, of which I have bought many. The sanding is quick, easy and 100% effective in eliminating the singing of the fin.
When sanding the trailing edge of the fin make it slightly asymmetric. If the trailing edge is symetric it will whistle due to tip vortices coming off the fin. I could go on hours on the hydrodynamics of this but it is very boring. Simple fix is clean up the edge and sand a little more off one side. Will make no differenve to performance.
I agree with TimB, make it asymetrical, but, just for the hell of it, I sanded both sides of one of my fins and that has worked as well. Make'em sharp, but beware the lethal weapon on back of your board.
When sailing hobie 16 we used to sand down the trailing edge of the rudders for the same reason, whistling. However we used to sand the trailing edge flat, not sharp.
to save reading about people losing limbs... square it off. My fins have a symmetric finish on the trailing edge and they dont whistle.
There are a few theories about the whistling... most are related to boundary layer instability. The boundary layer gets more sensitive toward the trailing edge, so it would not take much of a bump to cause an early separation. That can then do all sorts of hard-to-predict things. Like form a small acoustic resonant cavity in the water...
Tim, do you care to elaborate on the assymetric idea? Whats the basis? Tip vortices are part of the playing field on any foil of finite span.
Yes I don't get the assymetric shape either, the flow is going to be assymetric anyway unless going directly downwind, it's just going to mean the board goes better one way than the other. Think the main cause of whistling is a bump on or near the trailing edge, usually caused by a run or bead in the finish coat, that just needs to be staightened out. My fins also have a thin square back edge, I've got about 10 stitches at the bas of my left thumb to prove sharp fins aren't a good idea!
