Best Material to use to Repalce Floor

What is the best material to use to repalce the floor in my 1978 CC? Is it marine plywood, treated plywood, or some type of non-wood composite. And if it is a non-wood composite where would I get this material?

SkiLew

I used 1 piece of resin coated treated plywood to replace the variety of very very rotten floorboards under the glass of my '84 2001.

you glass over anything that you plan on using. Even if you use composite starboard you have to glass over the seams to seal the wood that is already there.

An alternative to marine plywood is pressure treated plywood that is first allowed to "dry" several weeks in the sun prior to using. The advantage over marine plywood is the rot resistance of pressure treated plywood. The disadvantage is that it is not a structural grade plywood. Either choice must be totally encased/sealed with epoxy resin and/or fiberglass once installation is complete.

I pulled up a floor in mine that had been previously replaced using 3/8" "exterior grade" plywood, resin coated, bottom only. It was poor grade, filled with voids, and only 4 layers. I replaced the original bulkheads, middle, and rear, and forward, with new crossmembers made from White Oak. Cut, planed, triple resin coated. I anchored the laterals into the primary stringers with a 3/16"X1 1/4"X 1 1/4"X 4" angles and stainless TEK screws, Into the secondary stringers with # 10 X 1 1/4" stainless wood screws (you have to be careful not to pilot drill thru the hull on these puppies). Then I used 17/32" 8 layer high grade plywood, coated three times, with a urethane resin, 6 coats on the edges. I used a construction adhesive on top of the stringers and all the laterals (oh yeah, i put in a few extras, under the seats, and the shaft packing access, and front battery access), laid the floor down in 4 pieces, and screwed it down after pilot drilling and countersinking, with the same #10 X 1 1/2" stainless steel flat head screws. Glue, carpet, and now I can have a watersking Elephant on board!

66:

As there are many good methods to installing or replacing floors, I am sure you method will perform very well. The only thing I would add to your write-up is the importance of sealing the screw holes prior to installing the fasteners. After the hole is pre-drilled and countersunk, you should seal the now exposed wood with epoxy resin (or similiar). The water will find that screw hole and start to rot the wood around it.