Hatch lid material

Dear builders,

Could you please share your opinion and maybe some experience on making stiff hatch lid for board compartment. On my build now I’m, using 15mm Plywood. But plywood will suck water and with time it will be destroyed. So now I’m looking for other options with the same 15mm thickness.

Please advise.

Thanks in advance!

CFK sandwich board, strong and light, it can be made thinner i.e. with 8mm core. Foam core with 2x 300g CFK on each side should be enough. Rohacell would be a good core material but not cheap. AirexC70.75 works as well.

Rohacell: Rohacell / Hartschäume / Sandwich-Werkstoffe - Suter Kunststoffe AG

Airex: Airex C70.75 / Hartschäume / Sandwich-Werkstoffe - Suter Kunststoffe AG

If you want to build it cheaper, you can also use a wood core, just make sure the edges are coated with epoxy or paint to avoid water entering the core.

I built a sandwitch board with rohacell and a box for my inflatable with airex, see here: Daniels (un)geared inflatable (slowly built)

The plates are very strong and still in use.

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Thanks for sharing. Probably the most cost-effective and lightweight solution would be to use lightweight plywood coated in epoxy. However, I will try to find something similar to Airex in my country.

I am currently making the top of the MALA box in Airex C70 in 15 mm thickness, the result is very rigid and very light. This is a lot of work:
2 layers of fiberglass on the inside and outside edges then 1 layer of fiberglass on the top and bottom (also covering the inside and outside edges) then 1 layer of carbon fiber on the bottom (on the MALA side) and 2 layers of carbon fiber on the top. And finally glazing before 2K varnish.

don’t forget to install the inserts (resin mixture + microballoon) before installing the carbon.

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Looks really good! (20 char)

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Skill level 10+ ! (20 char)

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Looks really nice, but it is too complicated. I’m trying to make my build as cheap as possible and at the same time reliable. So need to follow this strategy )