Re: Plywood vs. Marine Plywood
Most of the folks on this forum will tell you that using fir marine ply will save you money over using cheap construction ply and having the boat break or rot in a few years. But you'll have to glass it all to avoid checking.
They will also tell you that using fir marine ply and having to glass it all will cost more than using Okeme or Meranti marine ply and not having to glass it, or only glass the underwater parts of the hull. Epoxy and glass are not cheap, and involve a lot of labor with generally toxic materials.
Kinda like building a nice house or a cool car out of cardboard -- it can be done if you ignore code, but your work and carpet and paint and fittings will be wasted when the cardboard fails....
Bottom line = if you can't afford decent materials to build a 20' boat, get the plans for a 10' boat you can afford to build properly.
I ignored the warnings about cheap ply and used it to build the centerboard for my dory skiff, just coating it with a thin coat of epoxy, no glass.
Surprise, surprise, surprise...it failed, broke in half, and could have caused the loss of the boat under more extreme conditions. I rebuilt it from Meranti marine ply and fiberglassed it, and expect it to outlast the hull planks.
Non-marine ply bottom from my dory skiff - previous owner's big mistake, note the rot -
Cheap non-marine ply centerboard before installation -
After two hard seasons -
Replacement Meranti marine ply with glass -
Last edited by Thorne; 03-05-2008 at 06:58 PM.
"The enemies of reason have a certain blind look."
Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.