Typically you are required to license a pleasure craft in Canada. In order to do that you need to prove ownership. According to Transport Canada you do that by providing :
- name, address, and signature of previous owner;
- name and signature of new owner;
- description of the pleasure craft (make, model, and other details requested on the application form);
- hull serial number (HIN) or compliance label number (if available);
- pleasure craft licence number (if already licensed).
- A bill of sale or a signed purchase agreement.
I would retain the U.S. title document as support for your bill of sale.