Zero Flex DIY little foil board

[WH Lithuania]

Lowed my Moses T60 Sport as it has zero flex. But really need something much smaller. My friend shaper is going to make me a smaller board (around 111x41) but we not sure about the construction. I don't like the flex that comes with sandwich boards. What would be the stiffest DIY construction?

[kitexpert]

Make a thick foam board with double stringers (also gives good strength for foil attachment). Wide carbon strips on both sides on top of the stringers, then usual glass on top.

If it will be thin board using carbon is best way to make it stiff. Core is not that important, it can be plywood. Board that small will not be too heavy anyway.

[WH Lithuania]

Make a thick foam board with double stringers (also gives good strength for foil attachment). Wide carbon strips on both sides on top of the stringers, then usual glass on top.

If it will be thin board using carbon is best way to make it stiff. Core is not that important, it can be plywood. Board that small will not be too heavy anyway.

Thanks. Plywood is not that light, I doubt it's a good option for core.

[TomW]

Foam core about 30-40 mm thick.

Quick way: buy 2 pieces 120 x60 x50 mm xps builders foam. The blue stuff they usd for ground insulation.
Rough up one side of each a bit with 40g sandpaper. Glue together using PU wood glue. into 100mm thick blank.

Cut outline, shape in the bottom rocker, then top. Use an electric hand planer them sanding boards with 40g down to 120g.
Shape rails.
Drop in woodstringers or high density foam around foil plate. Extending forward.
Seal with epoxy and glass balloons, mayonnaise consistency.
Sand clean.
Glass 5 layers 6oz bottom, extra 2 layers 1/2 of bottom.
Deck you will need 5 layers 6oz, + 2 layers deck patches.
The xps foam is soft 20kg/m3..need a lot of glass.

Another way, but harder to get materials. Glue together 2 layers of 10-12 mm thick divinycell or corecell foam over a " rocker form ". If you get 80kg/m3 density it's hard enough to not use stringers around foil plate.
Then just cut outline, shape rails. 3x 6 oz each side. 2x extra glass on deck and bottom around and forward of plate.

Don't forget you'll have to have solid epoxy " plugs" where you will drill for mast plate. Cast those plugs in the foam before glassing and do in stages to avoid exothermic reaction that will melt your foam.

[WH Lithuania]

Foam core about 30-40 mm thick.

Quick way: buy 2 pieces 120 x60 x50 mm xps builders foam. The blue stuff they usd for ground insulation.
Rough up one side of each a bit with 40g sandpaper. Glue together using PU wood glue. into 100mm thick blank.

Cut outline, shape in the bottom rocker, then top. Use an electric hand planer them sanding boards with 40g down to 120g.
Shape rails.
Drop in woodstringers or high density foam around foil plate. Extending forward.
Seal with epoxy and glass balloons, mayonnaise consistency.
Sand clean.
Glass 5 layers 6oz bottom, extra 2 layers 1/2 of bottom.
Deck you will need 5 layers 6oz, + 2 layers deck patches.
The xps foam is soft 20kg/m3..need a lot of glass.

Another way, but harder to get materials. Glue together 2 layers of 10-12 mm thick divinycell or corecell foam over a " rocker form ". If you get 80kg/m3 density it's hard enough to not use stringers around foil plate.
Then just cut outline, shape rails. 3x 6 oz each side. 2x extra glass on deck and bottom around and forward of plate.

Don't forget you'll have to have solid epoxy " plugs" where you will drill for mast plate. Cast those plugs in the foam before glassing and do in stages to avoid exothermic reaction that will melt your foam.

Thanks TomW! What about using carbon instead of glass? 5+ layers of glass will be heavy. I would really like to get something around 2kg and super stiff

[tmcfarla]

I did 2 layers of divinycell (1/2”, I think it was 80 weight), glued together with gorilla glue. I don’t have a foam cutter, so the only shaping was cutting it out and sanding the rails round. I think top and bottom were each: 2 layers of 6oz carbon fiber twill and 2 strips of 6 oz unidirection carbon (each maybe 6 inches across). I put some extra layers of carbon where my feet and foil go. It is about 42” x 18” x 1” and weighed just over 2kg before I put the pad on. I’ve been using it for a while as my only foil board and it is holding up well. It has no flex at all, as far as I can tell.

I’m not very experience with this and I don’t have a workshop or garage. It took a while to do the first one, but wasn’t very difficult and turned out really well. Vacuum bagging was done with a vacuum cleaner and some over sized storage bags. The only difficult parts I ran into were 1.) after gluing the foam layers together, it lost a little bit of its rocker so ended up a bit flatter than expected and 2.) getting carbon fiber over the rails was difficult and unpleasant.

[bgpeters]

Where did you get divinycell sheets from?

[rynhardt]

I build corecell M80 core wakeskates that are 100cm by 40cm, approximately 20mm thick (approx because of the top concave).
Using approx 300gsm glass at 0deg yields a very stiff board.
Total weight with grind base is about 2.2kg.

So.. Cheapest option for you might be to just buy a wakeskate and try it first before building.

[WH Lithuania]

I build corecell M80 core wakeskates that are 100cm by 40cm, approximately 20mm thick (approx because of the top concave).
Using approx 300gsm glass at 0deg yields a very stiff board.
Total weight with grind base is about 2.2kg.

So.. Cheapest option for you might be to just buy a wakeskate and try it first before building.

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?

[tmcfarla]

Where did you get divinycell sheets from?

I got divinycell at Amazon (via some fiberglass supply store that sells stuff on amazon) it was about $80 for enough foam to build a pocket board. No idea about availability outside the US.