Friend of mine buys US boats all the time. The most important thing to have is the Title (ownership), the bill of sale and ensure boat numbers match on the title. The border seems more concerned about the trailer and yes, you still have to take the trailer to Canadian tire to get certified within a certain period of time. This is done all the time and just make sure you have the proper paper work as mentioned, pay the appropriate tax and It will be a breeze. Registration in Canada should be simple too. Color pictures of the boat, copy of the title(previous owner), copy of your receipt (bill of sale), copy of your license. This can be done on line. One important thing to remember is to keep a copy in safe place, of the receipt showing you paid the taxes and duty on the boat. 3 years from now Revenue Canada will be asking you to prove you paid the taxes on the boat. If you don't have that reciept you may have to pay again.