Thank you for your question. I look forward to working with you to provide you the information you are seeking for educational purposes only.
If you have a bill of sale and the proof that the boat is not stolen from the police, then you need to fill out a new registration form on the boat/trailer like it was brand new and just purchased. So the boat is generally registered with wildlife and fisheries (you do not say what state you are in) and the trailer is registered with DMV and this would be a brand new registration since it has never been previously registered.
we live in bushnell florida. also do i simply take the report from a police officer and a bill of sale to our county DMV just as we would the cars?