99% of the time, a "free" boat is just a way for the owner to get out of the cost of scrapping the boat. Nearly as often, the new owner dumps a bunch of time, and money into it, but can't complete the project for some reason, and the boat is offered for "free" once again.
It is important to understand that boat building is about as far away from house carpentry as the space shuttle is from the Wright brothers' plane. Houses generally don't twist and flex like a sailboat can, so a nail is often a sufficient fastener, for house building. What I'm trying to say is that whatever work done by the OP may need to be removed and begun again, using proper boat building techniques.
If I were you, I'd be looking for a complete, ready to sail boat, and sail during the years it could take to make a free boat seaworthy.