Is it possible my fin whistles but only on starboard tack? Pretty sure it's not coming from the rig

It is under water so should be hard to hear.

Yes fins whistle, I have a 50 cm tectonics that whistles and people can here you coming. You can file the trailing edge at a 45 degrees to try to get rid of the sound. Never seemed to slow me down, just got louder as you went faster.

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Hydrosurf said..
Yes fins whistle, I have a 50 cm tectonics that whistles and people can here you coming. You can file the trailing edge at a 45 degrees to try to get rid of the sound. Never seemed to slow me down, just got louder as you went faster.

Great, I did some googling and sanding at 45 seems to be the answer. I'll give that a go and let you know.
don't feel and sort of vibration and it doesn't feel draggy it's just really loud and annoying

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Ben1973 said..

Hydrosurf said..
Yes fins whistle, I have a 50 cm tectonics that whistles and people can here you coming. You can file the trailing edge at a 45 degrees to try to get rid of the sound. Never seemed to slow me down, just got louder as you went faster.

Great, I did some googling and sanding at 45 seems to be the answer. I'll give that a go and let you know.
don't feel and sort of vibration and it doesn't feel draggy it's just really loud and annoying

Foil masts can whistle, and you do the same thing for them, sand the trailing edge at an angle. Neil Pryde aluminum foil masts had that problem, one of their team foilers made a youtube video showing how to sand it.

I've read that you coat fins in fish oil

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Imax1 said..
I've read that you coat fins in fish oil

I though it was snake oil

Yes it is possible for it to whistle only on one tack. The issue is usually trailing edge related and as a fin travels through the water at an angle of attack if the trailing edge issue is only on one side of the fin the whistle can happen on one tack only. 600 wet and dry on a flat block. Run it down each side of the fin at the trailing edge on a slight angle...just a few light passses and it should fix it.

So if it only whistles on port tack what side of the fin is the problem??
I've sanded both now just out of interest.

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Ben1973 said..
So if it only whistles on port tack what side of the fin is the problem??
I've sanded both now just out of interest.

It may not be one side of the fin, it may be that on port tack you are subjecting it to more pressure, or pressure at a certain angle, that sets off the whistle. Thinking the whistle sound may be due to a harmonic vibration occurring in the fin, and sanding the trailing edge on both sides removes slight imperfections that are responsible for setting off the harmonic vibrations which are high frequency and so cause a whistling sound.

I sometimes get a whistle from my mast ext . That's where it seems to come from ? When reaching over 25 kts and only on a certain wind angle in one location ??? Strange .

Yeah on the fin it's mostly in my boom. Especially the aluminum ones. Their holes act like a flute at certain speeds. And if the foam insert shifts on one side it'll sound different on the two tacks.

Some fin brands do a clear coat after sanding and you can get a slight build up at the trailing edge. This is enough to cause a harmonic. Depending how the fin is racked when painting it may just be on one side. Also if the trailing edge has been sanded flat there may be a tiny burr left, again enough to cause the singing. If the fin is only making noise on one tack I would guess the problem is on the high pressure side of the fin ( leeward side) but not really sure.....

That would also be my assumption, but this is tricky stuff, you need a flow tunnel with coloured trails to find out.

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Imax1 said..
I sometimes get a whistle from my mast ext . That's where it seems to come from ? When reaching over 25 kts and only on a certain wind angle in one location ??? Strange .

Mast extension is completely covered by sail so unlikely, it's like trying to find where the creak is on a bike

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aeroegnr said..
Yeah on the fin it's mostly in my boom. Especially the aluminum ones. Their holes act like a flute at certain speeds. And if the foam insert shifts on one side it'll sound different on the two tacks.

After rigging duck tape the boom holes up, that will tell you.

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Ben1973 said..

Imax1 said..
I sometimes get a whistle from my mast ext . That's where it seems to come from ? When reaching over 25 kts and only on a certain wind angle in one location ??? Strange .

Mast extension is completely covered by sail so unlikely, it's like trying to find where the creak is on a bike

That's what I thought . Could air be sucked up / down the luff pocket ? Boom is carbon with foam in the centre , no flute holes .
It only happens in one location and one wind angle . From rough chop turning to flat water that is shadowed by a small island . Seems to always happen , only for a couple seconds , just before bearing off in the last of the chop going into flat water . Happens with different fins , sails and boards , that's why I don't think it's the fin . Could there be a strange pressure change on the water surface doing this to my mast ext holes ?

I had an older 8m Warp. Its the ONLY SAIL that makes my sdm extension whistle.
Have had fins whistle also. Usually G10. Do the sanding thing.
Kinda cool though coz its always at same speed.
No Gps?
Fin lets you know youre fangin along...