Rebuilding boat floor.
 

My wife, a cabinet maker, was approached about rebuilding the interior in an old boat. I was just curious if anyone has done this and if they had any advice. Can one use pressure treated wood or is marine grade plywood necessary? Any good options besides carpet for the floor that you would recommend? Any advice is appreciated, thanks.

I would recommend putting this thread on the general discussion.

There are very extensive discussions on this sort of thing on lots of marine-oriented websites. Doing the Google on that topic will get you lots of good opinions.

The biggest problem seems to be water penetration of the fiberglass or gel-coat either from the inside or outside of the main hull, especially for mass-produced boats made when fiberglass was just starting to get really popular. That rotted out the plywood core leaving vastly reduced hull strength (plywood is supposed to supply much of the stiffness and strength of that kind of structure). That same problem arose then they started using foam core laminates instead of plywood, or used plywood/fiberglass laminates for the top deck. When holes were drilled through a top deck for wiring or fittings, water immediately soaked into the plywood starting all kinds of rot.

My take on things so far is that plywood has to be totally encased in fiberglass wherever it will be exposed to water. Which pretty much includes floors. And a marine grade should always be used (birch?). Supposedly it's stronger and the glue is more water-resistant.

x2 ... i have seen these escalate exponentially in $$$ ... make sure their pockets are deep enough and they know the risks ... and you know the risks ... boat rebuilds and fixes are notorious for sucking the $$$ blood out of you

Boat rebuild
 

Not sure if you are speaking of fibreglass or aluminum boat ( eg, flooring, casting deck)?! If it's aluminum, using pressure treated wood is a "No No" as the cooper arsenate used to treat the wood will react with the aluminum,