Can I build boat transom in this way ?

I know wood transom will rot easily.Last month I bought a high density of foam board, I think it is the same as cutting board in my kitchen, and not strong as GRP board.
In my workroom there are many small GRP pieces left no use, such as cutted from hatches. Now I am thinking can I laminate them together then used as a transom
This will be much stronger and heavier then high density foam, aslo save much money.
How about my idea ? :?:

 

No good. Use plywood. Encapsulate in epoxy all surfaces. The transom might well outlast you if you pay attention to details.

 

why ??? I think they will last longer time then wood.

 

why ??? I think they will last longer time then wood.

 

No expert here, but I think if its the board used in cutting boards, it is
High Density Polyethylene Plastic

You are right about it being rotproof, but the question will be how successfully it will bond in layers, and how strong it will end up as.

Without having a sample, and knowing the size of the boat, my impression is that it may not end up sufficiently structurally stiff.

Waterproof fastening to the existing hull may create issues as well, as standard epoxy wont adhere to it very well

 

Your description of your idea is a bit vague and we don't even know what kind of boat you have -------and a lot of other details necessary to commenting intelligently.
You said "... cutted from hatches...". Cut what? Plywood? Fiberglass? Spend a little time, relax, and try to include as much information as possible.

 

I , agree 100%

 

HDPE (cutting board stuff) would make a fine transom, except you can't bond to it (no adhesive sticks to it), it's really heavy for it's strength and stiffness and you can't screw to it very well either. Other than these small issues, it's great. Lots of things, including boat parts are made from it, though usually through bolted together or to other things.