Manik - 07 September 2013 06:46 AM

... My thinking was, and still is, to have 6mm Okoume with a single layer of 200 or 250g/m^2 glass over it on the outside. Inside the cabin I would then have approximately 50mm insulation laminated onto the panel, with a bit of framing, and a 1.5mm plywood panel over the interior insulation foam, to get that nice wooden look again, and more importantly to prevent the interior foam from being turned to mush through abrasion, standing on it, etc.

With my present estimate I’m getting around 9.4kg/m^2 for cabin panels, and 6.7kg/m^2 for non-cabin panels (which don’t have the insulation or extra 1.5mm plywood). I’m hoping a total of 3mm epoxy is enough to get the wood coated on both sides, glass laminated on, and the insulation layers and covering plywood bonded together. Maybe that’s being way too optimistic though?

Do I have to glass both the inside and outside, or would glassing on the outside be enough?

Cheers,
Marco

Well… I wouldn’t say moved my cruising grounds, more like extending them a little. 😊 The Wadden Sea is my #1 destination, but if I can take the boat further north / have a longer season, then that would definitely be a nice extra.

Hi Marco,

Insulation:
I cannot share your idea about the insulation foam. Sailing season on the North Sea starts in mid april and by then its “warm” enough to go sailing without foam. Season in Finland starts beginning of may, when the ice is melted and then you will need no insulation, because the air is warm. Unless you want to sail in winter there is simply no need for it in a wooden boat. Winter sailing is no fun!

If you insist on insulation, why do you not sandwich two 3mm plywood sheets with 15mm foam in between. This is more than enough insulation for a boat.

Glass and epoxy coating:
The need of glass inside and out is a function on your inner supporting structure. If you have only a few frames and stringers its good to have a stiff ply panels, so laminate inside and out, but if you have reasonable framing only the outside will do. 200gr glass is enough in every case.

Epoxy coating is definetly not 3mm. I think you mean three coats of epoxy, this is around 300 - 350gr / m² total per side.

If you build with 6mm ply and some glass and epoxy, expect to have a panel wheight of 4,2 to 4,6 kg/m² ...  framing, fairing and painting extra.

Cheers, Michel

...Or you could build it with 3mm ply on the inside, then foam insulation / sandwich all over it and then just a heavier (normal sandwich) glass skin on the outside???? If you did ply on the outside, you would want to glass it anyhow…..You would want something more solid than a foam core on the bottom though.