Not the best idea.
Bob:This is really not the best idea. Crazy Dave just made a post about this for the trailer sailors. High pressure washing can harm the gelcoat. The other problem is that it can also wash out the caulking under any hardware (winches, cluthes, rails, cleats, tracks, stanchions etc). So if you must do it you need to be very careful and use as little pressure as possible (also remembering that MAYBE the pressure washer is not going to take off whatever you are trying to remove).My first recommendation is good old soap and water, some of the deck/non-skid cleaners seem to do a very good job too. If you have specific marks a little softscrub on the non-skid will sometimes help. I have tried the Island Girl Pink on non-skid that had sap and spider crap in it. It was the only thing that worked.So I would try everything else before power washing unless you are going to redo the non-skid .