Re: What and How to learn a boat's history?
If the boat is documented with the Coast Guard you can get some information about previous ownership by searching their database. It will tell you the names and locations of previous owners (assuming each renewed the the documentation when they bought it) and some other stuff like the year it was built and the model year. Nothing really that would help you in deciding to buy the boat though.
The best information you can get would probably come from a good surveyor that you hire to inspect the boat before you hand over your hard earned money.