noisy foils

   Contender board usually slanted back ( so the bottom edge is parallel with the hull). The leading edge is only vertical upwind in very light winds.  hence a gap in front of the board that's filled by slot gasket ..or not if water pressure is forcing it open.  Trying to peer down there whilst smacking along at 15knots is quite hard!

Might try the strip of rubber (physio exercise band stuff) at the gasket front.  Or replace the gasket anyway, maybe gone soft.

NB.  Not found any bumps on the foils and sticky tape made little difference.  But the trailing edges are rounded, might file them flat & slanted.

Ta for the suggestions.

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NickA Send Private Message Find Member's Posts Really should get out more Joined: 30 Mar 05 Location: United Kingdom Online Status: Offline Posts: 784	Post Options Post Reply Quote NickA Report Post Quote Reply Topic: noisy foils Posted: 03 Jul 22 at 4:25pm
	Contender board usually slanted back ( so the bottom edge is parallel with the hull). The leading edge is only vertical upwind in very light winds. hence a gap in front of the board that's filled by slot gasket ..or not if water pressure is forcing it open. Trying to peer down there whilst smacking along at 15knots is quite hard! Might try the strip of rubber (physio exercise band stuff) at the gasket front. Or replace the gasket anyway, maybe gone soft. NB. Not found any bumps on the foils and sticky tape made little difference. But the trailing edges are rounded, might file them flat & slanted. Ta for the suggestions.
	Javelin 558 Contender 2574

423zero Send Private Message Find Member's Posts Really should get out more Joined: 08 Jan 15 Location: United Kingdom Online Status: Offline Posts: 3420	Post Options Post Reply Quote 423zero Report Post Quote Reply Posted: 03 Jul 22 at 11:43am
	Is the board angled towards the bow? Rather than towards the stern,this could cause the water to drive up through the gasket. Failing that, glue a square of gasket material over the two strips, make sure it needs to be compressed when board is right down, could be a softer material than gasket.
	Robert

E.J. Send Private Message Find Member's Posts Posting king Joined: 19 Feb 06 Online Status: Offline Posts: 184	Post Options Post Reply Quote E.J. Report Post Quote Reply Posted: 03 Jul 22 at 11:29am
	No that is unusual, I’d immediately say it’s the gasket but if it it’s in good Nick a gap is being created forward if the CB somehow.

NickA Send Private Message Find Member's Posts Really should get out more Joined: 30 Mar 05 Location: United Kingdom Online Status: Offline Posts: 784	Post Options Post Reply Quote NickA Report Post Quote Reply Posted: 02 Jul 22 at 8:42pm
	Yes the contender. So it's easy to access the back edge of the centre board with some insulting tape. Lifting rudder too. On a related matter ..once the boat gets "humming" along, quite a lot of water comes up the front of the cb case and drains out the drain holes. Gasket seems good. Is this also normal? Wondering about slicing the gasket into two separate lengths, so the front bit can close with the board in "neutral" ie part up for planing conditions, but never heard of anyone doing that.
	Javelin 558 Contender 2574

Guests Send Private Message Find Member's Posts Guest Group	Post Options Post Reply Quote Guests Quote Reply Posted: 02 Jul 22 at 9:10am
	Nothing clumsy about Anti-Singing Trailing Edges - they are standard fit on the most advanced propellers. There must be some speed loss as kinetic energy is being converted to sound, but it will be minimal and it does sound good!

E.J. Send Private Message Find Member's Posts Posting king Joined: 19 Feb 06 Online Status: Offline Posts: 184	Post Options Post Reply Quote E.J. Report Post Quote Reply Posted: 02 Jul 22 at 8:16am
	Is it your Contender? Quite a few get this. As other have said it is often solved by making the back edge imperceptibly asymmetric. If your OCD won’t allow that sort of clumsy engineering the noise doesn’t affect speed. There is something quite menacing about the gradual increase of a low hum overtaking. Very Jaws, and can put your competition right off their stroke.

Rupert Send Private Message Find Member's Posts Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956	Post Options Post Reply Quote Rupert Report Post Quote Reply Posted: 01 Jul 22 at 7:02am
	I was always told to ensure the back edge of foils were chamfered slightly asymmetric, so one side would be 1/2 mm further aft than the other. This is supposed to change to stop the vibrations that cause the noise.
	Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686

Paramedic Send Private Message Find Member's Posts Really should get out more Joined: 27 Jan 06 Location: United Kingdom Online Status: Offline Posts: 929	Post Options Post Reply Quote Paramedic Report Post Quote Reply Posted: 01 Jul 22 at 6:38am
	It'll be the trailing edge off the board or rudder (I think you'd feel it on the rudder). You have a slightly fat spot somewhere. Cut a couple of strips of insulation tape about 50mm long and place a piece either side of the foil in question and then go sailing. Move the tape up and down until the noise stops. You've then found the bit that needs work. I don't think its performance detrimental.

NickA Send Private Message Find Member's Posts Really should get out more Joined: 30 Mar 05 Location: United Kingdom Online Status: Offline Posts: 784	Post Options Post Reply Quote NickA Report Post Quote Reply Posted: 30 Jun 22 at 10:54pm
	My boat keeps screaming at me. Maybe it doesn't like planing or maybe it's yelling with joy; but the faster we go the louder it gets. I think it's the rudder blade. I've faired the trailing edge, no chips or dints. It's a nice Wood and epoxy Milanes affair. Doubt it's damaging the speed much, but people certainly know when I'm about to overtake. Any ideas? Solutions?
	Javelin 558 Contender 2574