There was a thread about this a couple of months ago. It can be a little complicated because of the fact that the trailer is a "vehicle" and the boat is not. I have my 1448 w/25hp Merc insured through Progressive for about $100/year. When you are considering whether to insure or not, don't just think of replacement costs. Other things can happen too. Accidents, by definition, aren't planned events and they do happen. Medical and liability are also important issues and in our very litigious culture, you can get sued for just about anything. Best to insure. The price surely goes up with the value and hp, but worth it in any case.