Author Topic: 13 year old Finn Spencer passing everyone on a foil board at Paddle Imua  (Read 4564 times)

headmount

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For Downwind it's fantastic to be as light as he is.  Sam  200+, tried it and he simply said he failed.
Yes, for 80 lb Finn whatever size he is riding is a huge foil.   We did a downwinder yesterday and Sam tried it with his 10'6 foil board and Maliko Foil for the first time and did not get a single lift off, but it was only blowing around 15 knots and the bumps were small.  I think with 25 knots it will work, I'm waiting for the right day to try it.  I think it's really a matter of having the right size foil with enough lift and good conditions.  I'm thinking downwind foils for bigger guys need to be quite a bit bigger than even the Maliko Foil to work well.
I think what you wrote is important about 15 knots.  Even Finn's race day and video was much more than that.  So yeah it's not a light wind deal.  I'll bet Sam and you will rip once it's 25 plus.  The difference in wave size is huge from just 15.  Even 20 is a big difference.  Sam's cool and didn't mention the 15 knot condition because he probably doesn't like to put excuses but that's a legitimate one.

PonoBill

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I'm betting on the geezer foil. This is all good motivation to get me sanding the clusterfuck I built and try to get the drag down.
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808sup

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Sounds like a distinct humming as you are riding those foils. Is that from a vibration or cavitation?  I have a friend who's foil ( a different brand ) does that. He said it was normal for that one. I know the don't all make noise so what is the difference?

blueplanetsurf

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Sounds like a distinct humming as you are riding those foils. Is that from a vibration or cavitation?  I have a friend who's foil ( a different brand ) does that. He said it was normal for that one. I know the don't all make noise so what is the difference?
Yes, the Kai Foil hums quite a bit but I think it sounds kind of cool and does not seem to affect performance.  I was told it is from vibration at the tips resulting from imperfections in the foil shape and whatnot.   Some of my older surfing fins used to do that at high speeds as well. 
Alex Aguera told me last week that he is heading to the factory to work on improving the foils to reduce the noise.
For those not familiar with the sound, you can hear the humming noise on this video, a friend said it sounds like a fighter jet:

« Last Edit: May 13, 2017, 09:53:37 PM by blueplanetsurf »
Robert Stehlik
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southwesterly

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I really don't like it when I have fins that humm.

I feel like it's a dinner bell for big things swimming nearby. I hate being a giant lure.

Bean

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The trick to silencing a humming fin is to dull the trailing edge of the fin (220 sandpaper on the edge only, works well).  A little detuning goes a long way.

Beasho

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Two sources have confirmed that the humming is coming from cavitation off the trailing end of the horizontal stabilizer.  It's just cut flat ~ 1/2" square.  Some guy named Cort Larned and Travis formerly the chief Aeronauticist for GoPro.   

Sanding the end, which is solid composite, into a more aerodynamic shape will eliminate the hum.  Travis took it halfway down and the hum was cut down by 80%.
« Last Edit: May 14, 2017, 12:09:22 PM by Beasho »

blueplanetsurf

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That makes sense, the tail seems pretty clunky and I have heard of others that have modified it.
« Last Edit: May 14, 2017, 06:50:32 PM by blueplanetsurf »
Robert Stehlik
Blue Planet Surf Shop, Honolulu
Hawaii's SUP HQ
http://www.blueplanetsurf.com