DIY Home Made wooden Hydrofoil fins

[windfreak74]

I was thinking that maybe it would be fun to glue the twwo halfs of the foil with a polyurathane to make the middle a kink of vibration dampner.
Do you guys think it will do a good job?

[BWD]

I don't think it would have much effect.
Probably wouldn't hurt though, if you clamp it well.
If you use polyurethane, don't let it expand too much!

[zfennell]

Hi Pedro.

as long as all the planks in your core run full length, using just epoxy (IN THE CORE) will be fine.
shear loads are relatively low. Also, flexural modulus and strength (of bamboo?) are pretty good.
Hawaiis does it all with wood, but i think you should consider it your "factor of safety".

the core is pretty thin compared to Hawaiis (8mm vs 25mm) so that will be a problem w/o lots of reinforcement on the surface. maybe 10X more flexible due to geometry differences.

read this:
http://www.mothflyers.co.uk/blog/lets-build-some-foils/
(moth foils are very similar in size, so a good example. a google search will find other examples in the moth forums)

once you get a handle on that we can talk about whether you want glass or carbon and make a guess for how much.

also look at the kind offering from Europe2:
(viewtopic.php?f=196&t=2382637)

you won't need to get it right the first time.
he's given you a way to compare the stiffness of your strut with others.
if you are not satisfied with the results you can add more fibers before the board ever gets wet.

-bill

[windfreak74]

Wow guys!! thanks for all the input!
This thread is awesome!!

[Hawaiis]

I tried bamboo, it is ok if short enough, ie 18". My 24" wing was creating a resonance in the water. I use solid Koa wood for the strut, I bought pieces of Ipe(Brazilian Walnut) and lignum vitae just to try the stiffness. Hardest wood you can find or just a thin core and glass or carbon the outside.
Use epoxy, don't use polyurethane.

[zfennell]

...........or just a thin core and glass or carbon the outside.
.......

i agree.
i think this is the way he must go.
the core will offer shear and buckling resistance.
flexural strengh of wood is just a bonus

all longitudinal flex is restrained with uni fibers
all torsional flex is restrained with 45deg fibers.

this sounds more like Bille all the time
i guess we've come full cycle.
-bill

[windfreak74]

Great input!
Ok i have a 3 feet of 6 0z. carbón were would i gain more aplying it.?
fuselaje , mast or wings with carbón?
My thought was to use 4 inch strip cut in 45° to each side of the mast.and the rest wrap the hole mast in 0/90 in carbón on the outside to look good!
or use carbón in the wings and only use fiberglass on mast( i have 3 meters of 6 oz.fiberglass).I i can wrap about 12 layers of glass on each side.
or remake the mast in 22 to 25 mm and 135mm in chord.

Again im a a newbie in glassing and carbón!
opinions please?
Pedro

[Hawaiis]

Strut

[BWD]

Carbon +/-45 on the mast.
Cover the outer layer with a layer of fiberglass, protects against dings and fairing/sanding.

[Randahl]

This thread is pretty cool to read about guys on all points of the globe in various stages of R&D on their own foils. And who knows who else is out there fiddling away that doesn't post on this forum?

Foils and their function are sorcery to me. I was under the impression that if you didn't get your calculus right, account for all the variable and get your tolerances to the micrometer that your foil would fail miserably. To be honest when I first saw pictures of some of the homemade foils on here I laughed because they looked so hokey and I figured they would be flops.

This thinking is probably why I am one of the guys who shelled out a small fortune for a carbon fiber "professionally" crafted foil... the wizardry to make a functioning foil is beyond my technology.

But, I see videos of these foils actually working (to varying degrees of success) and it's undeniable proof that foils are within the grasp of mortals. Thanks to the guys on this thread for proving it. To be honest, I am in the infantile stages of learning to ride the foil, and I am much farther behind a lot of guys riding homemade wood foils vs. my space age carbon fiber bank breaker.

If I had read this and other threads before buying mine, maybe I would be taking a look at cheaper alternatives to what I ended up buying, and maybe I wouldn't be so paranoid about losing or destroying my foil and watching a few week's pay vanish. But the allure of lightwind and upwind riding is irresistible.

The only drawback to trying to learn on your own foil is that it's hard to tell if the foil is the problem, or if you are....

Keep at it, this is encouraging.