If it's on a trailer I'm going to assume it's a 19' Cape Dory
Typhoon. That year, probably worth $2,000-5,000 depending on condition and outfitting.
If I were you I'd go to Boats for Sale - New and Used Boats and Yachts - YachtWorld.com
and see what comparable boats of the same make/model and era are listed for. That's going to give you a better indication of it's real market value than our estimates.