Absolutely ,have to transfer,We were stopped by Homeland Security Zodiac coming home to the island from Friday Harbour.If you don't have the paper with your name on it,they assume you stole it.But when you do your transfer,have the old owner give you three bill of sales.One for the boat that you send in with your transfer application.One for the trailer which you produce in B.C to transfer the trailer to your name and get plates(not required because you fill out value on the transfer papers).One for the motors and all accessories,which you hold if anybody wants to add it all up ,they won't.You will save a bundle of tax money and it's legit,border guys told me I was smart to do it that way otherwise you get taxed on full amount of bill of sale you send in.