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Foil Board DIY

Forum for hydrofoil builders.


stevez
Medium Poster
Posts: 143
Joined: Wed Jan 13, 2016 11:17 am
Kiting since: 2008
Gear: Moses hydrofoil
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Re: Foil Board DIY

Postby stevez » Tue Jul 03, 2018 6:58 am

junebug wrote:
Fri Jun 29, 2018 1:56 pm
Allow me to amend my question — what does everyone think should be the minimum thickness for a 42x20in paipo made of strips of Paulownia?
Here's my 39 x 17in paipo made of strips of Paulownia which I finished building a few months ago.

It's about 2cm thick. It has just a single layer of 6oz glass top and bottom with a second layer over the base plate. No carbon except for a couple of small patches over the inserts that probably don't do much.

It pretty strong and stiff and is holding up fine. I wouldn't say there is zero flex, but there is zero noticeable flex with the above configuration while riding. I don't think it's strong enough for a surf foil, where you generally stand a lot further forward, and want to be able to pump it. But for a kitefoil like the Stringyfoil above, riding strapless, it's plenty stiff and strong enough.

So to answer your question, it does depend, but I'd say about 18mm is probably the minimum. It goes up if you're riding a surf wing, or riding with straps. Or you'd have to make it stronger with more layers of glass and/or carbon reinforcements.

The area that takes the most strain and is most likely to fail is the bottom of the board exactly at the front of the base plate. I put a rubber pad there consisting of an old car tyre material. Before I did that, with just the baseplate attached to the board directly, the fibreglass was stressing and showing signs of starting to crack after a few sessions. Putting a layer of rubber there seems to have resolved this.

It weighs about 2.6kg. This is my first build. I made a lot of mistakes, but it turned out fine in the end, and gets the job done.
20180703_121451.jpg
20180703_115208.jpg
20180703_115134_1.jpg

junebug
Medium Poster
Posts: 140
Joined: Sat Jan 04, 2014 4:14 pm
Kiting since: 2007
Gear: Twintip
Foil
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Re: Foil Board DIY

Postby junebug » Wed Jul 04, 2018 4:38 am

stevez wrote:
Tue Jul 03, 2018 6:58 am
junebug wrote:
Fri Jun 29, 2018 1:56 pm
Allow me to amend my question — what does everyone think should be the minimum thickness for a 42x20in paipo made of strips of Paulownia?
Here's my 39 x 17in paipo made of strips of Paulownia which I finished building a few months ago.

It's about 2cm thick. It has just a single layer of 6oz glass top and bottom with a second layer over the base plate. No carbon except for a couple of small patches over the inserts that probably don't do much.

It pretty strong and stiff and is holding up fine. I wouldn't say there is zero flex, but there is zero noticeable flex with the above configuration while riding. I don't think it's strong enough for a surf foil, where you generally stand a lot further forward, and want to be able to pump it. But for a kitefoil like the Stringyfoil above, riding strapless, it's plenty stiff and strong enough.

So to answer your question, it does depend, but I'd say about 18mm is probably the minimum. It goes up if you're riding a surf wing, or riding with straps. Or you'd have to make it stronger with more layers of glass and/or carbon reinforcements.

The area that takes the most strain and is most likely to fail is the bottom of the board exactly at the front of the base plate. I put a rubber pad there consisting of an old car tyre material. Before I did that, with just the baseplate attached to the board directly, the fibreglass was stressing and showing signs of starting to crack after a few sessions. Putting a layer of rubber there seems to have resolved this.

It weighs about 2.6kg. This is my first build. I made a lot of mistakes, but it turned out fine in the end, and gets the job done.

20180703_121451.jpg
20180703_115208.jpg
20180703_115134_1.jpg
Looks great! Thanks so much for the tips. I wouldn’t have come up with the car tire padding on my own.

How did you get the rocker in it?

stevez
Medium Poster
Posts: 143
Joined: Wed Jan 13, 2016 11:17 am
Kiting since: 2008
Gear: Moses hydrofoil
BRM cloud
Brand Affiliation: None

Re: Foil Board DIY

Postby stevez » Sun Jul 08, 2018 9:59 pm

junebug wrote:
Wed Jul 04, 2018 4:38 am
How did you get the rocker in it?
It's laminated in 3 layers. I got the rocker by clamping and gluing it bent.
Not as much as I would have liked, but enough to make a difference. I didn't allow enough for springback.
junebug wrote:
Wed Jul 04, 2018 4:38 am
I wouldn’t have come up with the car tire padding on my own.
A better solution is something like a 5-6mm perspex plate that Greg from BRM and others were using with the paipos. It's hard but has a bit of bend, so it distributes the load over a wider area.


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