Help!!Axis S Series, 68cm front , 370mm rear on short fuse, My foil used to hum a fair bit so I watched a couple of YouTubes on how to fix it and got busy with the sand paper... Bad call!! now when I foil it's like kiting with whales!
Now on almost every reach I get a variety of creaks, hums, and groans. I can feel the vibrations through the board, its horrible.Can anyone advise me on how to tune a foil into silence?

Out of curiosity, what board were/are you riding?

Are you sure your fuselage isn't bent, you haven't shimmed it and there are not nicks out of the mast?

Did you see this video, I haven't tried it myself so not sure if it works.

Buy a Moses foil, I have 4 front wings and the only singing is from me

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warwickl said..
Buy a Moses foil, I have 4 front wings and the only singing is from me

And your retailer and the Moses management.

They do look good and smooth though.

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Kamikuza said..
Out of curiosity, what board were/are you riding?

Are you sure your fuselage isn't bent, you haven't shimmed it and there are not nicks out of the mast?

Pretty sure, short fuse is new and the mast look clean. I haven't shimmed it at all
Using it on a Slingshot Dwarfcraft 4'6"

I to have the same axis foil and get the hum . But only some times I was thinking it came from the mast and wind direction over the mast.Thanks for lettings know I think I will live with the hum.

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kitefree said..

Kamikuza said..
Out of curiosity, what board were/are you riding?

Are you sure your fuselage isn't bent, you haven't shimmed it and there are not nicks out of the mast?

Pretty sure, short fuse is new and the mast look clean. I haven't shimmed it at all
Using it on a Slingshot Dwarfcraft 4'6"

All assembled right and tight?

Some boards seems to generate more noise than others...I used 4 different boards with the same foils and the thinner or longer boards tended to make more noise. But it was intermittent and barely noticeable, at best.

Did it do "hum" from day one? Can you change out parts with someone else, like swap a part at a time?

Had a mate with the same problem on his new Axis foil, couldn't fix it, returned it for a refund.

I think if you square up the trailing egde it should fix it. a sharp trailing edge is the cause...
It work's on fast cats so should be the same. or as said above
just get a Moses. None of mine hum and they are very smooth to ride.

I had a noise that gradually got worse over a couple of years on my JShapes freeride (carbon). It eventually got so bad that I could feel the vibration through the board and I had to do something about it. I got serious with a file, filing a 45degree angle from top to bottom on both the front wing and stabiliser.
The result was a completely extinguished noise/vibration and an increase in performance of at least 15-20% speed and carving wise. After 8 months there are absolutely no indications of the problem returning.
Its a little hard to tell from your pics but it seems you have fallen short of bringing the angle all the way through to the bottom of the wing, leaving a squared of trailing edge. If that is the case that is the likely failure point of the repair... a squared trailing edge is definitely not what you want. I would suggest that you not leave a squared edge as that defeats the purpose of reshaping the trailing edge. The purpose is to encourage a surface that allows free flow with discouragement of cavitation. A squared edge will encourage cavitation.
Its worth noting that theoretically the stabiliser is inverse to the front wing and should (theoretically) have its trailing edge shaped from bottom to top. I missed that detail when I reshaped mine and both front wing and stabiliser were reshaped from top to bottom. However the result I got was so good that I left it as is.

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snalberski said..
I had a noise that gradually got worse over a couple of years on my JShapes freeride (carbon). It eventually got so bad that I could feel the vibration through the board and I had to do something about it. I got serious with a file, filing a 45degree angle from top to bottom on both the front wing and stabiliser.
The result was a completely extinguished noise/vibration and an increase in performance of at least 15-20% speed and carving wise. After 8 months there are absolutely no indications of the problem returning.
Its a little hard to tell from your pics but it seems you have fallen short of bringing the angle all the way through to the bottom of the wing, leaving a squared of trailing edge. If that is the case that is the likely failure point of the repair... a squared trailing edge is definitely not what you want. I would suggest that you not leave a squared edge as that defeats the purpose of reshaping the trailing edge. The purpose is to encourage a surface that allows free flow with discouragement of cavitation. A squared edge will encourage cavitation.
Its worth noting that theoretically the stabiliser is inverse to the front wing and should (theoretically) have its trailing edge shaped from bottom to top. I missed that detail when I reshaped mine and both front wing and stabiliser were reshaped from top to bottom. However the result I got was so good that I left it as is.

Ta, really helpful. I'll try it and let you know how it works out.

If you want to drive yourself mad, there's a section in Principles of yacht design by Eliasson Larsson...around page 128, late in chapter 6.

Can find the pdf online, or Google Books: books.google.co.jp/books?id=rn4lAgAAQBAJ&printsec=frontcover&dq=yacht+design+larson&hl=en&sa=X&ved=0ahUKEwiOgb-ZrKnpAhUXiZQKHVloDYgQuwUILzAA#v=onepage&q&f=false

page 143

Was out on a long tack today and the mind was wandering ...

Seem to remember one of the guys who introduced me to that book, was homebuilding a foil and trying to work the kinks out -- he put tape on the TE to simulate a sharp edge, before he sanded it down. Was successful IIRC...

Whoops, there it is:

EDIT: huh, can't post a link ... lets see ...

extreme kites forum (no space, .com.au), search "tape" and click the "Naish foil board" link