Deck materials for a 34' sailboat....

[Roly]

If you have access to a female deck/coachwork mold, what would be the cheapest and lightest material system that would provide the required stiffness?
polyester-CSM-WR-CSM /Foam/polyester-CSM-WR-CSM
polyester-CSM-WR-CSM/Balsa/polyester-CSM-WR-CSM
6mm ply/foam/6mm ply/ light epoxy-glass cloth outside.
Another format?
Weight saving is more important than cost. (Marginally )
The hull is strip planked glassed both sides in epoxy. (A rebuilt strip-planker)

To elaborate, my current deck/coach/cockpit is way over weight from previous owners reclading over defects (rot) and to change the cosmetic "look" with the times. I have access to a complet fibreglass deck mold so I could make a new one!
Why bother? Same reason we replanked and glassed the hull with different scantlings.
I could remodel the current coachlines to a more aesthetic profile and use it as a male mold for foam and glass replacement
in epoxy, but it seems more work than using the mold.
Sounds like a very odd thing to want to do; I have done much crazier things to old houses, which, BTW, I advised the client against!
Besides, this is fun!

[Roly]

Could a female mold designed for polyester, be used with polyester gelcoat and then epoxy and foam, so as to save fairing & finishing?
Just rambling here;They all seem possible.

[marshmat]

Since you have the mould already, I don't see any reason not to do the whole thing new. Especially since you say the current deck is pretty wrecked and hastily patched.
Foam will probably be cheaper than balsa. I would do this as a proper composite laminate and not a plywood sandwich. If you use a core (such as foam), as opposed to a solid fibreglass layup, you should consider vacuum-bagging the laminate. You'll also want to make sure you get any structural ribs, etc that were on the old deck, built in the same places and to the same strength on the new deck.
It's hard to come up with many details for a laminate schedule without knowing a lot more about the boat; photos help.
I'm not a fan of CSM; it sucks up a lot of resin and is not as strong as cloth (although some people insist that it's necessary against a core). Cloth and roving are best where possible. A mat or veil layer is nice to have against the gelcoat to avoid print-through of the cloth texture.
I see no reason why a polyester mould would not be fully compatible with epoxy; epoxies are not particularly reactive and don't tend to dissolve things.

[Roly]

Thanks for the reply Matt. Project at



We hope to lose a lot of weight topside to make up for added weight in the hull. As we have the mould a whole new deck seems to be the way to go.
Tom has give us the scantlings and we added a 50% SF. (hence the weight)
The coach roof is 30mm thick in the mast area. (mast keel stepped)
It is not glassed inside yet, and would be way easier losing the existing deck.
Also sheer plank is currently compromised by chiselled in rebates.

Sounds an ill conceived project but it is great experience for us.