DIY hydrofoil with rubbish and an angle grinder

I have been drooling like a dog in front of all these masterpiece of carbon fibre but sadly couldn’t afford a quarter of the cheapest hydrofoil Dave could propose on this forum (very good job anyhow Dave)... So I decided to build one myself with what I had: some old kite gear and few tools (including an angle grinder).

A mate gave me a used skateboard, I closed my eyes and though very very hard at what an Eppler 817 profile looks like, then took my angle grinder and shaped a big fat front wing. I had a bit of resin left from another job to make a quick glassing and protect the wood in case my sharpened log needs to fly more than once.




The rear wing is made with pair of short race fins screwed together with the insert of the mini-tuttle box. I paid attention to put the flat surface of the fins facing upward - to create some lift downward as they say on kitefoil.forumactif.org/.



Back from work, I found what looked like a gate made from stainless steel tubes badly welded together in the bin of an industrial area (what else could I dream of!!!). Without hesitation, I pulled out my angle grinder to make few cuts, glued the bits with araldite, which didn’t work so I drilled some holes, chucked a couple of bolts and my first fuselage was born.



Tired of such a success, I took my phone to check the web and found that TKF was selling their aluminum mast rejected from the production line. $260 poorer and 2 weeks later, I had 2 nearly spotless mast delivered at my door (so far, the best looking parts of my project).



I had this old race-board prototype sitting there doing nothing and thought that despite of the explicit design, it could do the job. I drilled a mast box and reinforced it with pine wood treated against termite (I’m playing my best cards). The female tuttle shape was moulded in resin with a fin protected with duct tape. I screwed some off-cut from my gate on the deck to hold the bolts that will attach the mast to the board.



Then I bolted everything together with Ikea screws and bolts stolen from the steering of my daughter’s bike, a bit of duct tape here and there to cover the f*** ups then ran to the beach like a fat kid on a mud cake.






On my way, I realized that I had spent only 4h on the foil of a friend before so I’d have to learn how to fly and to setup a foil at the same time (smartly, I decided to wear a helmet and impact vest).

With the sun setting, I had just 15min for the first try in dying wind but I managed to make it fly for about 50m. That was sufficient to make me the happiest man on earth.

The second session was brilliant, except the fact that I had to keep the board pointing down dramatically to maintain a not too unstable fly. I realized later that the fuselage was bent.

A stronger fuselage with high penetration nose was made for session 3 where I could fly very well but only in one direction (one of my front line was 50cm shorter than the other one...that didn’t help).





Session 4 was 10km of awesome ride. The foil is taking off at very low speed, remains stable, goes upwind, downwind, and don’t really bother the ventilations. My max speed was stunning 30km/h, a record that can only be broken...

So that didn't cost $2000 ???
How could it possibly work LOL

S H I T .......H O T !

Love it - and very inspiring - seems the trickiest piece might be the mast which finding a couple of seconds on line was the go. Have now been eyeing up my kids old skate boards visualising which would be high wind and which would be low wind foils. Great job with the Tuttle strengthening....

I really hope this is real. Any chance of a photo of it in action?

Well, alcohol probably had a bit to do with the nose. I'll make boobs for the next one so that everyone is happy...
Foil + board cost me less than $200 and could probably be nailed working a full week end if I had to do it again.

Foil mass is 3.5kg / board is 4.5kg

As weird as it can be, it looks like anything can fly as long as the front wind creates lift and the rear wing balances it.
How long it lasts depends on how stiff mast + fuselage + attachment to the board are.
How fast it flies is directly related to the drag.

I ll try to make vids this we if wind blows.

Nice man.

I am puzzled with the TKF, are they based in Au? Would be great if u can share the contact details, I recon will go your path than :) Cheers

I've just ordered one :-). Here comes a whole new adventure!!!!
Hey Luc, any chance of catching up for a chat sometime?, I'll bring the beer :-)

Thanks everyone for your messages and glad to see there s few DIYers around.

Hence the previous references to penetration