Nope.
Not structural and fiberglass will not stick to it for long.
Been discussed here many times.
Try checking out coosa board. It's a composite material that's waterproof that I know some who have the extra $$$ use.
Try using the search function. You will find a lot of reading material on the subject. You may even want to start with archbuilders thread, 16' Nescher ski boat complete restore. He used seacast for the transom and stringers. Another one would be micks110, 1962 Arkansas Traveler restoration. They both detailed their projects very well.
Take care and have fun.
Bob
I know i never want to do this again and i will if i use wood.
38......if you do it correctly....the wood will last 40 years. far longer than you will have the boat.
if you do it even margionally you should get 5-10 years out of it.....just make sure that you read read read here and let us guide you.
cheers
oops