I have a AV Nuvolari Freerace 119L and when it gets going the fin starts buzzing, getting worse the faster I go until its screaming at me. I'm thinking this must be slowing me down . I also noticed at speed some water coming up through the holes where the fin screws are.

Finbox on this board is a Deep Tuttle, and I have a decent fin - Tribal 34 Slalom fin with a deep tuttle adapter.
Originally the fin set about 3 mm low in the box so a quick coat of spraypaint and now the base of the fin fits flush with the board.
The fin feels really tight in the box to me and I always crank the screws pretty tight too.

Has anyone had this problem and managed to fix it?

If there's water coming up through the fin bolt holes, then I'm guessing you've not got rubber washers under the normal stainless washer? I have heard that can cause issues that you might not think it can. The other thing to consider, if you've brought the fin back out to flush with the board bottom then the Tuttle tapers are no longer meeting. That will mean that there is a gap that water can pass up into, hence the water gushing up through the bolt holes.

I'm not sure if all that has anything to do with the humming you're experiencing (there's other things it can be), but they're easy things to rectify and see if they fix it. Tap washers can be bought cheap at Bunnings (that's where you get your rubber washers from). Try taking the spacer out and see what effect that has. Yeah, it's not perfect hydrodynamics, but provided it's not way up in the box, it shouldn't cause massive issues.

Thanks for the suggestions Subsonic. I do have rubber washers under the normal washers. I also had these issues (buzzing and water coming up through bolt holes) when I sailed the board before spraying the fin base to make it fit better.

Here's the fin sitting low in the box before I added a layer of spray paint - it now sits flush with the board.

Try lightly sanding the TRAILING edge of your fin. Just up and down with 800 to 1000 grit paper. Dont go too hard.
A flush fitting fin is a big step, good work.

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ka43 said..
Try lightly sanding the TRAILING edge of your fin. Just up and down with 800 to 1000 grit paper. Dont go too hard.
A flush fitting fin is a big step, good work.

What he said but sand at 30 deg ,2 swipes each side then test. Most likely it's a drip line from the spray coat

That looks like a terrible fit, sitting really low in the box. I would guess is lose n the box as its bottoming out before the taper is locking it

I bought an AV Nuvolari Freerace 119L in 2022 and had the same issue with fins sitting too deep in the box. I bought a Select S-Max fin but other tuttle box fins had the same problem. I thought it might be just my board. I fixed the problem buy putting a plastic shim down the front of the box. It took a few goes to get the thickness right, the bottom of a plastic takeaway box from the Chinese was ok.
It was a bit disappointing they couldn't make a box to the standard measurements. Other than that, the board is really good. I did my fastest 500m for 7 years on it soon after buying it (since buying bought Ezzy Lion sails in 2015), in a choppy water state in Poole Harbour. Its really comfortable in chop.

No buzzing sounds, so guess its your fin.

But do get water coming out of the top of the box.

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Great video! That's exactly what I see.
Regarding the buzzing I'm going to try sanding the tailing edge as suggested above.

Great video! That's exactly what I see.
Regarding the buzzing I'm going to try sanding the tailing edge as suggested above.

If there's water coming up there's probably air going down. If there's no run on the fin trailing edge, and sanding it flat, doesn't fix it. it could be air whistling down to the fin. This will also cause spin outs, so sealing the screw holes would be a big priority for me.
If the rubber isn't sealing, is it because the non slip runs next to the screw holes?

The board is recessed where the fin bolt holes are, so no non-slip there. I'll have a closer look before my next sail to see why those rubber washers aren't sealing.

They have to be tight on the bolt
like have to screw the washer into the bolt
else it won't be an air seal.
but TE just as likely.

as an aside, pretty crap to have a fit like that they obviously mounted the box too low

yep that's gonna suck water up not being level ,can you try another fin ,or pack it

The trailing edge is the usual culprit for the "singing".
But air leaking down is no good either...

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Mark _australia said..
They have to be tight on the bolt
like have to screw the washer into the bolt
else it won't be an air seal.
but TE just as likely.

as an aside, pretty crap to have a fit like that they obviously mounted the box too low

Don't get me started again on the windsurfing industry's inability to make fin boxes the same size.

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Ben1973 said..
Don't get me started again on the windsurfing industry's inability to make fin boxes the same size.

I think part of the problem is the imperial /metric thing

Fin and foil hum can also just be part of the dynamic of that particular blade and its flex properties, the foiling GT40s racing on Sydney harbour this weekend just scream, I mean scream,- unbelievably loud. Talking to my colleagues who work on the super maxis about vibration in the boards they use the general conclusion is that it's just a thing that can't be gotten rid of. They are constantly tweeking and assessing, the joys of open check book professional sailing.

I have G10 flying object fins that I use when I'm in any way worried about dragging on the bottom and they sing at a high pitch but I also have carbon fins which hum at a much lower note. I like the noise it's a bit like my engine rev audio clue as to when I'm lit!

Your fin fit however is crap. If that's where the fin has to sit why not fill the area of the fin base facing out (or up in that picture) that is below deck level with some good fairing compound to flush it up? Must only be a few MM but still rubbish for your laminar flow?

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peterowensbabs said..
Fin and foil hum can also just be part of the dynamic of that particular blade and its flex properties, the foiling GT40s racing on Sydney harbour this weekend just scream, I mean scream,- unbelievably loud. Talking to my colleagues who work on the super maxis about vibration in the boards they use the general conclusion is that it's just a thing that can't be gotten rid of. They are constantly tweeking and assessing, the joys of open check book professional sailing.

I have G10 flying object fins that I use when I'm in any way worried about dragging on the bottom and they sing at a high pitch but I also have carbon fins which hum at a much lower note. I like the noise it's a bit like my engine rev audio clue as to when I'm lit!

Your fin fit however is crap. If that's where the fin has to sit why not fill the area of the fin base facing out (or up in that picture) that is below deck level with some good fairing compound to flush it up? Must only be a few MM but still rubbish for your laminar flow?

He did say "Originally the fin set about 3 mm low in the box so a quick coat of spraypaint and now the base of the fin fits flush with the board" photo is before the fix

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choco said..

peterowensbabs said..
Fin and foil hum can also just be part of the dynamic of that particular blade and its flex properties, the foiling GT40s racing on Sydney harbour this weekend just scream, I mean scream,- unbelievably loud. Talking to my colleagues who work on the super maxis about vibration in the boards they use the general conclusion is that it's just a thing that can't be gotten rid of. They are constantly tweeking and assessing, the joys of open check book professional sailing.

I have G10 flying object fins that I use when I'm in any way worried about dragging on the bottom and they sing at a high pitch but I also have carbon fins which hum at a much lower note. I like the noise it's a bit like my engine rev audio clue as to when I'm lit!

Your fin fit however is crap. If that's where the fin has to sit why not fill the area of the fin base facing out (or up in that picture) that is below deck level with some good fairing compound to flush it up? Must only be a few MM but still rubbish for your laminar flow?

He did say "Originally the fin set about 3 mm low in the box so a quick coat of spraypaint and now the base of the fin fits flush with the board" photo is before the fix