Re: transom rot
Depends on what you're using and your method but yes, you need to prep your wood.
Basically what I did:
1. Make sure it's dried out (especially treated)
2. Glue 3/4" together wood
3. Cut out shape
4. Coat it twice with resin then on the third coat added fiberglass cloth
5. Glued, tabbed and now finishing up the last layer of fiberglass