So with this swell that we have been enjoying.

Ive been putting some K's on the car up and down the coast getting into some waves that only break when it gets big...chasing swell direction, wind and tide to find some cracking waves!.......anyway as the swell was backing off yesterday I decided to have a Go on the 11ft Chris Craft at a right reef which was still over head but abit fuller on the tide yesterday.

Although i had kinda noticed it before it was really noticeable in the bigger waves with alot more power.

The fin was making a high pitch kinda humming sound...especially when i would come off the bottom or do a turn on the open face.

It sounded like when you blow into an empty beer bottle and was quite load!.....considering the fin would be largely underwater it must be really loud to hear it when i am riding the board!...probably sending a Pod of Dolphins to beach themselves or similar.

The fin is tight in the box and screwed down firmly.

Anyone had a similar experience?

BTW: the board performed admirably, although its probably at its limit in those kinda waves......although it does have a Wiamea Big Gun kinda outline...the rails and the nose rocker are certainly tuned for a different stlye of wave.

only with a lexan star fin many years ago at the local bommy.

I think it's fun

Try lightly sanding the front and rear of the fin with 1200 wet n dry..sometimes a rough edge causes that Hummm

True - chips & tiny fractured chinks from bloody reefs another culprit

The Rick Jacko Alloy Joy board I surfed for about 15 years used to hum when it got into full flight, like Ob I liked it

Nothing to do with the leading edge, everything to do with the trailing edge.

Theres a blunt area on the trail edge,the water wont flow off it cleanly.

Run your finger along it and feel, with a fine file(like the ones used to sharpen chainsaw blades) just make the blunter parts a little sharper.The hum will disappear....The cavitation is slowing your board a touch,file away and surf faster!

Alter seeing the damaged and sometimes even the death caused when flesh hits the trailing edge of a fin at any speed, I going to continue to blunt the rear of every new fin I get

I started doing it after I saw the damage it did to chrispy years ago, and I've never stopped since

Trixie Tawnymuffel has been telling the Bowlo servery girls she is presenting you with her reknowned Rum Ball Hum when you get here Obs

Interesting.
I'm sure we used to stop skiff foils humming, (20 plus knots through the water) by squaring off the trailing edge - sand a 2mm or so square end on it. But it was a long time ago and I may be mistaken.

Select to expand quote

wavemaniac said..
Nothing to do with the leading edge, everything to do with the trailing edge.

Theres a blunt area on the trail edge,the water wont flow off it cleanly.

Run your finger along it and feel, with a fine file(like the ones used to sharpen chainsaw blades) just make the blunter parts a little sharper.The hum will disappear....The cavitation is slowing your board a touch,file away and surf faster!

what he said

Interesting comments...fin is brand new and razor sharp on trailing edge...it seems to to happen more when the fin is under pressure but I think it sounds kinda cool.
i was just worried it may be if the fin was not square in the box ....but if it's to do with the edges then I'm cool with it.
board performance is unreal so was more curious than anything.
cheers for the replies

I've had it with a few boards and it is the trailing edge.

i would fix it as getting rid of it has improved the performance of my birds dramatically. Fasterand looser, which must be a good thing. I didn't notice any difference in hold and one of them is a 8' semi-gun so hold is important. Personally I don't like it as in the back of my mind I can't help thinking what sections would I otherwise make, or what turns I am missing out in because the slower board is making me lose time and position on the wave even if I do surf to the end of it.

mine have all been on glassed in fin boards.