IMHO Boats are tough to sell. The best time to sell is now, because as soon as it gets warm in the North East, people think of doing warm water things, like boating. And anyone that buys a boat in the fall/winter will be looking for a deal (just as you would).
If you want to sell, do it now. Waiting until the end of the year may mean getting a lower price, if you sell it at all, and if not, then you end up paying for preparing it for the winter layup, storage, etc. Then next spring, you start all over again.

Of course, now there is another year of depreciation on it.
If you are sure you want to sell, do it now, or take the change and possible price hit later. If you do sell it now, I'm sure you have some boating friends, you know the best thing about boating (from a cost point of view) is "knowing someone that owns one"!

Good luck.