When it was time to get rid of my old boat, I sold it to M&M Marine Salvage. I didn't get much for it - maybe $100, but that's better than paying dump fees. The business is on Jenness Hill Rd, Meredith - just north of town a bit off route 3. It wasn't the smoothest transaction I've ever done - but the boat was gone.
http://www.mmsalvage.com/