Proper Replacement Plywood Sizes

[Radeleur]

OK, so I have spent 3 months reading (and reading and reading more) and researching this.

Each person, place and source have their own opinions regarding this.

One thing, that I have seen more often than not is to replace with in-kind size. Meaning, if it had 3/8, to replace with 3/8.

By doing this in today's world, with the available supplies and proper knowledge about encapsulation, it will actually be better than before in most cases. My example is the cockpit flooring in my 1989 Champion. Upon removing the floor, I learned a couple things. In 1988, wait he said just said 1989, that is correct. My boat is a built in 1988, model year 1989 boat. Anyway, first, they used AC plywood for my cockpit floor plywood and second, it is NOT glassed on the bottom. It is just resined. So, if I used the same size and applied resin and 2 layers of FG on top and bottom it would already be better than the resined bottom FG top.

Additionally, in the case of my Champion, when originally built it was glued down to the stringer tops and nailed, yes, I said nailed, down.

I welcome alternative thoughts and discussion.

[Seriouslyjim]

Hello, Radeleur...

A couple thoughts (and I am by no means an expert)... I'm in the process of replacing all of the wood decking/seating/live well tops on my '94 Cajun 179. The ply was so rotten I cannot tell just what thickness it was, originally. And in the spots where the wood seemed mostly intact, it was thick but definitely NOT a marine ply. Going with 3/4" Marine ply to replace and the trim issues are definitely a pain, though manageable so far. My flooring used steel sheet metal screws but I don't believe they even aimed for the stringers... just screwed through the fiberglass subfloor rather willy-nilly.

Anyway, if you have spots where the original floor "inserts" under overhangs or otherwise must fit into a slot thickness-wise, be careful of too much resin/glass/carpet thickness. Oh... and NOTHING is a straight angle cut on the wood in my boat... must have that sleek, streamlined look, don'cha know? Radius-ed corners, beveled edges, back edge wider than the front edge, etc... definitely an exercise in patience and care. Been picking up good tips on the forums here...

Good luck... take care!

[rgsauger]

If it had 3/8 with one side glassed, then 8mm-5/16 glassed on both should be fine

[rojoguio]

Cajun used End Grain Balsa too. I remember their old brochures, they had pictures and articles touting the superiority of End Grain Balsa. Well, plywood would have been much better. Just heavier too though.