To replace a boat transom, assemble a carriage bolt, fiberglass gel, wood glue, plywood sheeting, hammer, Sawzall and electric drill. Examine the type of engine the boat has. Remove the outer drive if the engine and external drive are attached.
Remove the rivets that hold the old transom, and carefully bang it out using a hammer. The old transom wall should be used as a template for the new one. Choose the appropriate thickness of the wall to make it easy for replacement. Use the proper equipment during the replacement. Use a Sawzall reciprocating saw for the outboard engine, or use a cut out stern drive opening for an inboard engine.
To get the proper thickness, use waterproof wood glue to join the pieces of plywood together. Protect the wood by applying fiberglass gel over it, and give it enough time to dry. After the fiber gel is applied, it forms a layer that protects both the inside and outside wall of the boat. This strengthens the transom and makes it durable.
Attach the new transom with carriage bolts, and then apply a marine grade sealant to the seams. Allow it to dry for approximately 72 hours. For the outboard engine, replace the transom cap and then bolt it.