[Rich]

One thing that I use that seems to clean better than most is "Roll Off".

In fact, when someone often washes their boat and there is some stains left behind, I often walk up, spray on some 'Roll Off' and hit it with the same brush they were using to clean the boat. They are often amazed that the dirt/stain came off so easily, especially after they just tried to scrub and clean the spot.

I wouldn't use it on the whole boat, but I use it for spot treatment. I keep a bottle with me as I'm washing my boat.

If the boat does NOT have bottom paint, and the bottom has a any water stains on it (which it probably does) the easiest thing to use is "On Off". Follow the directions. But I have used a garden sprayer myself. Just don't get it on any galvanized metal trailer or your I/O, and again FOLLOW the directions on the label, this is a strong acid based cleaner.

Parafunalia has both of these on their shelf for sale.