BC grade exterior ply checking?

[DrainBamage]

I've been reading on boat building sites that some types of plywood will check and delaminate unless encased with fiberglass. Sounds like marine grade fir is the most common to do this. Has anyone experienced checking on their boat floors? I don't want to put carpet on the floor I'm installing, but I also don't want to coat it with an anti slip paint only to have cracking later on.

Any insight is greatly appreciated.

 

[jigngrub]

Seal your decking with 2 part marine grade epoxy and you won't have to worry about any checking and you won't have to use any fiberglass cloth.

 

[DrainBamage]

Thanks, I did buy marine epoxy but wasnt sure if i needed fiberglass. I'm also considering MDO, since it takes paint really well.

 

[tomme boy]

All of it will check over time. Seal it with at least 2 coats of epoxy and then paint or cover with carpet. I have built several boats out of ply and have had one start to check a little. Since then all surfaces have been covered in cloth and none have done it.

 

[jigngrub]

Some people don't realize there are 2 types of marine resin, polyester resin and epoxy resin. Epoxy resin is strong enough to use by itself and I prefer and use 4 coats for an exceptionally tough and durable finish.

Polyester resin is very weak by itself and has to have the reinforcing of fiberglass cloth or mat. Polyester resin will crack and peel after about a year if used by itself.

MDO plywood coated with epoxy resin will be your best build. I like MDO better than the Douglas Fir marine grade plywood. MDO is very strong and designed to be used in wet/damp applications. We use it on the construction site to form concrete walls, so you know it's strong and water resistant.

There are only 2 better grades of plywood for boat building. HDO and CCA kiln dried pressure treated plywood... but both are very expensive and MDO gives you the best bang for the buck $$$.