EVERY Boston Whaler has water in the " closed" cell foam . That foam breaks down from the constant pounding of the hull . This fact does not keep people from buying them as they run just as good as when they come out the factory door . Weighing it is useless ,unless you scaled it when it was delivered . There are to many variables, including the usual disclaimer, " factory weight listed is within + - 5-10 % of that number . Not familar with the boat you're looking at or its construction materials. I would look into that , if all composite , I wouldn't worry about the foam being wet , unless it sits low in the water . A surveyor on a used outboard 17' inexpensive boat better be dirt cheap , something most people don't have done on that size hull .