click link then on your state it will tell you all you need and have the forms to print.
GOOD LUCK
http://www.discoverboating.com/owning/register.aspx
Here's what the link says
Transferring Ownership of a Watercraft
If the watercraft is not titled, simply complete the back of your watercraft registration. If you have lost the registration, then a complete bill of sale with the year, make, hull identification number, registration number (if available), and the names and addresses of the buyer and seller may be used to transfer ownership.
If the watercraft is titled, the assigned title is used to transfer ownership. If the title or registration is lost, a duplicate can be acquired by the owner from a Secretary of State Branch Office. Without an assigned title, registration or bill of sale, a court order or surety bond is needed to transfer the ownership. For more information contact your local Secretary of State Branch Office or the Michigan Department of State, Communications Section at (517) 322-1460.
If the new owner does not want a title and the watercraft does not need a title to list a lien (bank loan), the previous owner’s title is surrendered when the buyer transfers the registration into their name. The Secretary of State Branch Office will arrange to have the previous title cancelled