If your looking for forums to sell your boat, without paying a fee, I would suggest using this site, as well as other Bass Boat Boards.
I have sold 2 Demo boats in the last 2 years. One was sold from here on the Boats board, and the other on Bass Boat Central. Another good place in BFHP.
If you are looking to pay for advertising, I would suggest www.boattraderonline.com , there you can get it listed in the boat trader that arrives statewide every Friday, and list it online to viewers nationwide.
Typically, a boat like yours is easier to sell, so you probably want to post it here on the boats board, as well as some of the other discussion boards that allow it, or have a designated place for Boats For Sale.
Hope this helps.