Re: The number one way to wreck your boat
I use a pressure washer on my boat, but it is not a high pressure gas unit that could take your fingers off, it is a little Karcher electric unit. It does a great job of taking a winter's worth of green slime off the decks. I am very careful not to direct it at deck fittings where there is a danger I could force water under them, although I doubt it could do any harm to properly bedded fittings. I just use it for the larger surfaces, and then I go at the nooks and crannies with brushes.
As for the bottom, I see no harm in using a good pressure washer to clean the slime off when I haul out, in fact I find that is just about all I need to do in the way of prep before a fresh coat of antifouling. (assuming there are no barnacles or mussels of course!)
1979 Santana 30 Tall Rig