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Attached-on Hydrofoil for TTs

Posted: Fri May 25, 2018 7:47 pm
by jorg
great initiation. It is very interesting concept. The designer got some funding through some private sources and is going through his 8th version of this attached-on hydrofoil systems for twintip boards. It is low cost and a smart solution to make light days more fun.

Looks like he's got more exploration/devs to do and looking for testers all around world. Contact him if you wanna be part of this development

James Crook
Email: info@forty1kitesurfing.co.uk
Website: https://www.forty1kitesurfing.co.uk/version-8/
Social: https://www.instagram.com/forty1kitesurfing/

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Re: Attached-on Hydrofoil for TTs

Posted: Fri May 25, 2018 10:21 pm
by iriejohn
Hydrofoils on a TT which would work in shallow water and bring the kiting threshold down a few knots would be interesting.

Re: Attached-on Hydrofoil for TTs

Posted: Sat May 26, 2018 1:11 am
by BWD
Cool! There was a guy 5-10 years ago who made foils for his twin tip that attached to the fin holes.
He was in the Pacific Northwest I think. Wrote it up
Online, said it went fast and could jump but not turn. Having the area out at the tips gave too much inertia to be able to maneuver. This central foil idea looks smart, avoids that issue.
I have also wondered if a somewhat more conventional foil on a really short mast, say 20cm, could be fun at all for shallow water on a skimboard or paipo....

I’d like to see some video of this thing though!!

By the way, I think there is something similar in South America, heard about it in Uruguay but the guy who made it was not around when I was there...

Re: Attached-on Hydrofoil for TTs

Posted: Sat May 26, 2018 1:52 am
by chemosavi
I’m the guy in the NW who made the foils. Out of stainless steel.
They were true foils in that they generated lift, which believe it or not, is different than most of the ones people use today which are more like fins.
Terrible porpoising problems with mine. You get up on the foil and then the reduced water friction would cause massive speed increase and then the foil would cavitate badly and eventually start to plane. Awful scenario. Up and down, up and down. Plus they were a bitch to turn - my hips hurt like crazy after a session.
I loaned the foils to Armin Harrach, the owner of Fylsurfer Kites and his results were the same - no good.
But maybe these are different. It would be great if they were.

Re: Attached-on Hydrofoil for TTs

Posted: Sat May 26, 2018 5:15 pm
by jorg
Could it be yours?

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chemosavi wrote:
Sat May 26, 2018 1:52 am
I’m the guy in the NW who made the foils. Out of stainless steel.
They were true foils in that they generated lift, which believe it or not, is different than most of the ones people use today which are more like fins.
Terrible porpoising problems with mine. You get up on the foil and then the reduced water friction would cause massive speed increase and then the foil would cavitate badly and eventually start to plane. Awful scenario. Up and down, up and down. Plus they were a bitch to turn - my hips hurt like crazy after a session.
I loaned the foils to Armin Harrach, the owner of Fylsurfer Kites and his results were the same - no good.
But maybe these are different. It would be great if they were.

Re: Attached-on Hydrofoil for TTs

Posted: Sat May 26, 2018 5:37 pm
by Peter_Frank
chemosavi wrote:
Sat May 26, 2018 1:52 am
I’m the guy in the NW who made the foils. Out of stainless steel.
They were true foils in that they generated lift, which believe it or not, is different than most of the ones people use today which are more like fins.
Terrible porpoising problems with mine. You get up on the foil and then the reduced water friction would cause massive speed increase and then the foil would cavitate badly and eventually start to plane. Awful scenario. Up and down, up and down. Plus they were a bitch to turn - my hips hurt like crazy after a session.
I loaned the foils to Armin Harrach, the owner of Fylsurfer Kites and his results were the same - no good.
But maybe these are different. It would be great if they were.

They were true foils in that they generated lift, which believe it or not, is different than most of the ones people use today which are more like fins

What do you mean by this ???

Every single windfoil and kitefoil are horizontal wings with a very specific profile to obtain the best possible lift or lift/drag ratio.

None of them are symmetrical, and even a symmetrical or flat profile generate lift and dont act like fins at all, so I dont understand what you imply in above statement ?

8) Peter

Re: Attached-on Hydrofoil for TTs

Posted: Sat May 26, 2018 8:55 pm
by mikelet
It seems to me ,and it's just my opinión ..that bi-directionality it's not compatible with foils at the expenses of losing a lot of the performance as the foils sections (cord of the foils) should be flatter on both ends of the board to not cancel each other going in either dirección ....kind of trying to taking off a plane going backwards....

Re: Attached-on Hydrofoil for TTs

Posted: Sun May 27, 2018 8:56 am
by chemosavi
I am wrong about the "true foil" bullsheet. Apologies. Peter's right. Something someone said got stuck in my head like a kernel of popcorn in teeth.
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A foil with a flat bottom and a symmetrical curve on top does generate lift in both directions. This is not bullsheet. Good popcorn....
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So they can be bi-directional - just not as efficient. I do know mine had too much curve and generated too much lift. Less would have eliminated some of the porpoising.
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There was some guy in the UK, I think named Radic, that was working on a bi-directional foil about the same time as me. He was very top-secret about everything, have to off you if I show you, kind of thing. Maybe he's one of these people with this new incarnation..
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One other thing that concerns me about this new one is how low the foils are. Every time the water hits the board bottom it's going to create lots of drag. Seemingly.
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Yes, those are my foils. On the yellow Dr L board. This was all back in the days when nobody was using a foil, except for Laird Hamilton, and with boots. He offered to let me try his foil in Hanalei, Kauai and I declined since the rooster tails his falls were producing seemed unhealthy. How dumb was that?

Re: Attached-on Hydrofoil for TTs

Posted: Sun May 27, 2018 8:04 pm
by windmaker
mikelet wrote:
Sat May 26, 2018 8:55 pm
It seems to me ,and it's just my opinión ..that bi-directionality it's not compatible with foils at the expenses of losing a lot of the performance as the foils sections (cord of the foils) should be flatter on both ends of the board to not cancel each other going in either dirección ....kind of trying to taking off a plane going backwards....
:thumb: :thumb: :thumb: Anyone who has a minimum experience with hydrofoils knows the benefits of longer mast. Unless the water is mirror flat can't see how one could ever make a consistent flight with this one .

Re: Attached-on Hydrofoil for TTs

Posted: Sun May 27, 2018 8:32 pm
by mikelet
Any vessel or machine created by humans with a foil ( think of the sail of a boat , a wing of an airplane , a surfing fin , a kite, motorboat propeller,etc...) it has a Leading edge and a Trailing edge and a cord between them for creating high and low pressures at either faces. so no bi-directionallity possible ( unless as stated before at the cost of a poor foil desing and performance and relying on AoA's.
Let's say more , it 's Anti -Nature ...
We copied foils from bird wings and fish fins ......and i don't noticed there's birds or fishes flying or swimming Bi-Directionally.... :nono: