You inherited it, so you have no stake in it nor any capital. No loss for you any way you look at it.
Go on NADA and look up what it would be worth. That's your base number.
Donate it to some charitable organization that accepts boats. They will sell it and make a profit, to give to poor children or some other group. Use the base number as your tax deduction.
In the end you will make more that trying to sell it, plus you will have the satisfaction of helping others.
I know a lot of people that have yard sales or sell their crap on Craigslist. Personally, I simply donate any un-needed stuff to the Salvation Army and I don't even bother taking the tax deduction. Some things are more important than worrying about a few dollars. Plus, the donation is simply a lot less hassle.