This was a 1994 Reinell 20' ski boat that had been only superficially cleaned in 11 years of use. A 40 hour project, but it's looking beauteous again. :xyxthumbs
On the hull (as recommended by autopia members): soak with water, degreaser, and acid cleaner, then pressure wash. Buff with wool pad and 3m heavy cut compound, 1000-1800 rpm.
The interior vinyl was cleaned, then dyed, then water sealed. You probably won't be dyeing, so use a good, aggressive vinyl cleaner. Mine is proprietary, supplied by my local supplier.