Home made Hydrofoils

I see Kiteforum has added a new section for home builders

I tried to, nothing to report, had an issue with my mast insert.

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Plummet said..
maybe today. I've been skunked the last 2 weeks with the wrong conditions.

Got out maybe 10-14 knots. 10m edge. To start with I would just shoot out of the water like a rocket. No mater how much front foot pressure. I came to the conclusion the front hood was too far back. Repositioning it work and no more rockert ship launches. About 100 crashes later I managed a token 10m glide. Wohoo. Then a maybe a 20m glide followed by some porpoising.

godammit the small foiling I did felt grand.

Now i'm hoping for a little more wind so I don't have to work the kite so much.

Welcome to the hooked on foiling club. Plummet

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Plummet said...

Plummet said..
maybe today. I've been skunked the last 2 weeks with the wrong conditions.

Got out maybe 10-14 knots. 10m edge. To start with I would just shoot out of the water like a rocket. No mater how much front foot pressure. I came to the conclusion the front hood was too far back. Repositioning it work and no more rockert ship launches. About 100 crashes later I managed a token 10m glide. Wohoo. Then a maybe a 20m glide followed by some porpoising.

godammit the small foiling I did felt grand.

Now i'm hoping for a little more wind so I don't have to work the kite so much.

If you are working your kite as beginner, go up a size. It is too hard trying to get up on a wing, find your balance point and fly your kite all over the place as well.

When first started in 10 knot conditions on the LF, I was flying a 19..... while young Jordan Gridis was flying a ten and doing 2.5 times my speed. Having the big kite and pull allowed me to forget about everything but trying to foil.

Today it was blowing 20 knots and I was flying a 5.5m kite. I got better.

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dachopper said..
Is it fair to say though, that you can learn to balance on the foil, without the kite ( depowered at 12 ) , or balance on the foil with the kite powered and in a lower position, requiring "lean" on the board.

Are you ontop and balanced, ontop and leaning, or just leaning right over when powered downwind?

In the beginning, you need to be able to get on the board easily, build speed up quickly but controllably, standing dead straight up on the board, then letting it rise up and getting on with fighting the foil. All the porpoising and wiggling you do will suck your efficiency.

You can sheet in and get lift but any extra lift you get from a powered kite will decrease your weight on the board, and you'll risk getting lobbed.

Leaning the board and loading up is good for small kites and light wind but in the beginning is harder to control the balance, and work the kite too--muy difficult.

Dead-straight up-and-down takes away a lot of variables. Any weight off the center of the balance will do all sorts of horrible things, until you get used to it.

I found having the kite closer to the water took away the variable of any lift from gusts reducing my weight and causing ventilation, but increased the odds of (what felt like) building runaway speed. I was still riding with the board straight at that time.

Better to start on top of the board, with a big kite with lots of "depower" at the bar, that you're super-comfortable with flying, and ride the apparent wind from the kite and then try to just ride the foil.

But riding the foil without the kite is something you need. Getting used to instantly adapting to having pull from the kite then having NO pull from r kite is vital, especially for foiling jibes. Again, takes practice I think. Might be easier for experienced directional riders...

Wohoo. First session on the hydrofoil with real mans wind. topping out at 26 knots and lulls to 10 knots. Had a swell ranging from 1.5 to 3m. That was bloody challenging. Took the 8m and trimmed in the gusts and worked in the lulls. god damn the HFhas a massive wind range! Broke through and now i'm up and riding skimming the surface and getting glides between the swells. Freaken fanastic. There was one point where the wind backed off to 10 knots or so for 10-15 mins. all other kiters couldn't stay upwind and I was the only one out. Even with my pleb status I was still upwinding on the 8m. Yeha!...

I finally finished my foil project. I am pretty happy with it. Not the most beautiful ever but it works.

Tested it yesterday alongside my DIY surfboard. Conditions were rubbish. Very gusty wind and messy chop.

After a few attempts to get up I finally got my feet on the board and dived the kite slightly it rose up out of the water. Unfortunately I only managed to stay on one second.

After a few more tries I decided to call it quits and try when conditions were better.

I am just so happy that it works technically..now i just need to learn to ride it!

On a different note. I was struggling to keep the board pointed where i wanted to and it just kept turning and flipping onto its side. I think the chop must've played a role but it might be me.

Any advice how to get going on my foil without falling off?

The water mightve been a bit shallow so maybe the wings were hitting the bottom when i twisted it. I dont know. It was just a bit deeper than the foil. Will try deeper water next time.

In the meantime any ideas and advice welcomed!!??


[:

D]

Sweet. Its freaken cool to ride something you have made yourself.

Just keep at it man. You will get smashed for the first few sessions and it will feel all wrong and completely stupid.
But that's ok its part of the learning curve.

I made the mistake of setting my front foot strap too far back. I would just rocket ship out of the water each time I tried to launch.
If your doing that try a more forward position.

A good piece of advice I found was do the first few sessions trying not to foil. Weight heaps forward and try and keep the foil down and do surface riding.
As for the foil having its own mind in the water. yes they do that. It takes a while to get the technique to man handle them. Once the foil is in front of me I Grab the top rail with my hand and use my knee to lever the board on its side ready for the water start.

For me 13-20 knots on the 8m is idea.

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MozKiter said...
I finally finished my foil project. I am pretty happy with it. Not the most beautiful ever but it works.

Tested it yesterday alongside my DIY surfboard. Conditions were rubbish. Very gusty wind and messy chop.

After a few attempts to get up I finally got my feet on the board and dived the kite slightly it rose up out of the water. Unfortunately I only managed to stay on one second.

After a few more tries I decided to call it quits and try when conditions were better.

I am just so happy that it works technically..now i just need to learn to ride it!

On a different note. I was struggling to keep the board pointed where i wanted to and it just kept turning and flipping onto its side. I think the chop must've played a role but it might be me.

Any advice how to get going on my foil without falling off?

The water mightve been a bit shallow so maybe the wings were hitting the bottom when i twisted it. I dont know. It was just a bit deeper than the foil. Will try deeper water next time.

In the meantime any ideas and advice welcomed!!??


[:

D]

Looks nice. Wood and glass?

Water starting -- hold the tail, front foot in the strap and use that to keep the board on its side with the mast on the surface. You should be able to float on your back with the board perpendicular to the kite. When you're ready to go, send the kite (gently) and sink the tail with the back foot. That'll load the kite and push the board onto your feet. And should stop you from trying to edge the start.

With your water start, initially your goal should be to get onto the board and ride it completely flat and standing straight up and down, bearing slightly downwind. You won't be able to edge the board and keep everything balanced at this stage....

If you surface ride, you'll track upwind like a rocket anyway, so get some space from the shallows before letting the speed build and the foil rise.

Kamikuza. Yes glass and wood.

Pro Merc.... how's it going ? Any progress?

You should see what I have sitting in my shed !

So. Lesson learned for me this week. My first 10 sessions I have the wrong rear stab angle which was making the foil a lot harder to ride. It was rear responsive and twitchy. Tho since I'm learning I didn't know that's not how hydrofoils are.

Changed from 2 to 3.5 aoa and its a different animal all together. Its way more stable and easier to ride.

Morale of the story. If you a building a new design make sure you can adjust the rear stab angle.

My first foil was built modular, everything disassembled, you could say I still have the same foil but every part has been replaced at different times after it broke or required upgrading to a different design.
So I have gone from a foil with alloy and wood components to a full carbon design, I found that vac bagging the easiest way to build it, a front wing is about 4 hours work. The fuselage was trickier to build as I moulded it in two halves using electrical conduit, using plasticene to make flat spots for the wings. I then imbedded nuts to attach the wings, then glued the halves together and wrapped it in carbon.

As for the rear wing, I now have 2 washers under the front, this pushes the nose down as I was finding the nose wanted to lift as speed increased. It is now fairly balanced with no nose lift with speed changes.

That sounds like your permanently mounting the mast to the fuselage - when you say threaded bolt and glass it in, is that correct ?

Permanent mounting is by far the strongest and stiffest form to construct the foil and mast together. If your using carbon however, you need to be careful about galvanic corrosion, and about locking in metal against carbon as it will react.

If your wanting a removable fuselage, you have 1 option. You need to fit a barrel nut sideways - using the mast to take up the compression load, but not a hollow mast, it should be solid atleast in that area to spread the bolt compression. If u use an insert with the barrel, so long as the barrel gets to the surface of the mast, the compression load should be OK, the hole may wear or deform over time. Make sure the edges of the hole are atleast 2x the diameter of the barrel nut away from the end of the mast _ or if u using composites, the barrel may push a slot vertical through the bottom of your mast and become free if the hole is close to the end.

If you don't use a barrel nut, and have something that is contained inside an insert, the critical thing here is making the insert stay put inside the mast.

If the mast is composite layup, you need to somehow get the insert in there as the first part of the layup so u can vacuum bag and squash the fibers onto the insert / nut. Galvanic corrosion is again an issue here with wrong material choice. But, if you do it successfully, u get an insert that is going nowhere, and is absolutely rigid with the mast. U can't thread composite.

Nick.