Re: transom question
The best way to test a transom is to actually drill a few holes in it from the inside. Of course, when you are buying a boat you are not allowed to do this. For fiberglass boats tapping the outside of the hull will give you an idea. A sharp tud generally means a solid hull. Dull "tuds" means wet wood or rotted wood. Thing is, it generally takes for you to have heard these before before you can learn the sound....
If it is an outboard you can try to see if the transom will flex while pushing in the lower unit.
Fixing a transom is not technically hard, but is a lot of work. Go to the restoration forum and look at the projects there and read what it takes...