Georgia does not issue titles for boats, however they do register boats for the purpose of fee collection. You can't file for a lost title when there isn't one to find. Saying that, a search of FL DMV tells you how to do it. Basically the seller needs to provide the last registration paper work and a bill of sale to you. Call or stop in at your local DMV - A lot of states do not title boats and there must be a way to transfer. Here in GA cars, trucks and motorcycles are not titled after a certain age. FL has a way to transfer these also. Here's a link for FL DMV title/registration
http://www.flhsmv.gov/dmv/FFFVO.pdf
It's a pdf so it might open slow.