If your boat is near Baltimore, then you might not have too many barnacle problems. Otherwise the pressure washer is the first place to start.
What I've found helpful, if it's pretty clean in the first place, is using a drywall sander. Basically a long stick with a swivel head that holds the sanding medium. Which is like a gritty screen. Any hardware store will have them. Then you just wet sand either with a water hose or a bucket of water. The best part about it is no dust!
1973 Jensen Ranger 26