Ok, does anyone know why my foils hum? One rudder and one d/board get a real sing song going as soon as the boat reaches a certain speed. I can't be fast and I'd like to eliminate it but I'm at loose end having checked the alignment and I've also tried fairing but no result. I have a suspicion it might be that the gelcoat isn't bonded to the glass laminate in some places. That's about all I can think of as being the culprit.
Any other ideas?
Bern

There's been several threads about this in the past - but it's very likely the shape of the trailing edge of your foils. If they are very symetrical, they tend to oscillate quickly creating the hum. You want to chamfer one side of one trailing edge slightly and this will set up a very tiny imbalance/vortex that keeps the foil from vibrating. You can accomplish this with by scraping a pair of scissors up the trailing edge of the board. Sometimes you can accomplish the same thing by a tiny chamfer on both sides.

Years ago, My Catapult boards used to sing very loudly. My Spitfire boards do it a bit on a close reach under spinnaker once the speed picks up.
Maybe I should do something about it, but I think that it sounds cool.

I said it once before in another thread...but when I take someone new out sailing and they ask me "what's that NOISE!??" I reply: "That's the fat lady and she's warmin' up!"

Jake,

IIRC, it was "Thats the fat lady, you'd better hold on!"

yeah - that's better.