TOPIC: Advantech for floor

I am under way on a classic build and wanted to know others experience with Advantech. www.huberwood.com/advantech/products/advantech-sheathing - It came highly recommended so I bought 3 sheets 3/4 inch and it seems to be good stuff. I was leery about OSB but was assured it is better than marine ply and people have actually tested pieces of it submerged in water for years with no rot or delamination or significant change in weight. I plan on one piece for the floor and the rest to make a rear bench seat, front floor, front V-berth platform, steering helm box, etc... I will be spraying Spray-Lining and Coatings polyurea liner over everything with a very mild texture. Also for flotation - 2 part closed cell 200 board foot foam spray kit from Tiger 2 inches thick along all the sides sprayed over with the same liner polyurea and covered with sheething leaving a gap of 2 inches from the floor so if any water intrudes it will drain out eventually

Looks like you did your homework. I checked the website link you provided it says greater resistance to swelling and delamination. It's not waterproof but nothing else is either except a complete composite resin or plastic. Plan on replacing it in 50 years. Go for it and let us know how it works out for you. Do you plan on glassing over the top or just painting?
I'm working on a project now but am going a different route that I've never seen before. Replaced the floor with original regular plywood but will be putting down an overlay of FRP. Fiberglass reinforced plastic. I've used the stuff before but not for anything like flooring. Worth a try. There is no heavy abuse on a small trailer boat so it should work out.
www.fiber-tech.net/frp-panels