Zero Flex DIY little foil board

[rynhardt]

I had plywood wakeskate, but it was way too heavy. Need to find one in composite construction.

And the major question - where do you buy those high-density foams?

I source my foam locally (South Africa), which is imported by a boat building supplier. Maybe contact a boat-builder in your area?

[WH Lithuania]

Not much boat builders here really

I'm thinking about the stringers. Does making a groove and filling it with carbon fiber + epoxy work well for max stiffness?

[rynhardt]

Not much boat builders here really

I'm thinking about the stringers. Does making a groove and filling it with carbon fiber + epoxy work well for max stiffness?

Stiffness is all about the laminate on the outside of the core. The only reason you'd want a stringer inside the core would be to avoid the core from compressing under load, i.e. if you use something like expanded polystyrene and you don't want dents.
With structural foams (Airex, divinycell, corecell, pvc) something like 1Mpa compressive strength (corecell m80) is plenty strong enough to not need stringers.

Say you weigh 90kg, that's 883N. Area = 883N/1000000Pa = 0.000883 sqm = 29mm x 29mm.
I.e. if you put your entire weight onto an area 3cm x 3cm, corecell M80 could handle it just fine.

[TomW]

Corecell / divinycell can be hard to get in small quantities. But it's best way for beginners.
You can use less glass with the 80 weight. Xps is super soft.
I think you will waste your money on carbon. But if you insist, get the 200-250g unidirectional, 1m wide and use it only on deck and bottom, slice it into 3 strips 33cm wide. Get 2 meters. don't wrap rails. You'll have to do the vacuum bag thing with vacuum cleaner. It's good cheap way.
You'll not get down to 2kgs. That's pro level built first build. I'm struggling to get there. Down to 2,3 kg...

[WH Lithuania]

Yea, it's complicated with those high density foams here as there is really no way to buy it unless in bulk orders.

I'm just wondering is it possible in garage conditions to achieve something close to production boards. Moses T60 Sport has zero flex, from the outside it looks like it's molded two-piece board that is glued together. Not sure what is inside, maybe somebody knows? Is that just the molded shell that makes it so stiff or there are some other tricks? And how to achieve it without molding

[Kykeon]

Stiffness is all about the laminate on the outside of the core. The only reason you'd want a stringer inside the core would be to avoid the core from compressing under load

Same laminate with thicker core will have the same flex? Or I misinterpret your writing?

[rynhardt]

Stiffness is all about the laminate on the outside of the core. The only reason you'd want a stringer inside the core would be to avoid the core from compressing under load

Same laminate with thicker core will have the same flex? Or I misinterpret your writing?

Same laminate with thicker core will be stiffer.

[TomW]

WH,

Agree with Rynhardt.

Yes you can get pro results in your garage. But not first board and without vacuum bag.
You are in Lithuania? must be boat building in Finland.
I'm a bit lucky. Divinycell has a factory 60km from my shop ( garage) . But still have to buy a few full 2,4 x 1,2 m sheets to make it worth it.

[TomW]

You can try this:
Get the 1200x600 x50mm xps foam sheets from builders supply.
Follow my earlier instructions to shape it. Keep your final shape around 40mm thick, thinner at nose.
Drop in wood stringers all the way through the board where foil will be mounted. 150 mm between. Foil plate has 90 mm hole center. Of course you can fabricate glass/ epoxy stringers on a table and drop them in.

To compensate for soft foam, and have more durable deck you can vacuum bag on a layer of glass and thin wood. A veneer about 1mm is good. You can get strips of it and piece it together. Or if you can get 1-2mm plywood, available at hobby suppliers.
If your deck is flat then it's easy. You can use vacuum bag and vacuum cleaner trick.
After it cures clean it up and glass the whole thing.

It's not going to be 2kg!

[TomW]

You can get a stringerless eps surfboard blank from Seabase.eu in UK.
They cost about 70£, of you buy 3, shipping is about 100£. ( to Sweden, so I bet Lithuania is the same)
They have 2,3lb ft3 foam.