Once registered in Canada, it's just another boat. Write up a Bill of Sale with full names, addresses, (use Driver's Licenses) the boat registration and HIN numbers, all included items such as downriggers and electronics and the total Sale/Purchase Price. You should list and price a kicker and accessories separately to minimize tax. Both Parties must sign and date it. An identified Witness is necessary, too. It's the responsibility of the Purchaser to register the boat and to pay the tax.