This stuff works great. Tonight I decided to use it to scrub the cockpit out, I have guests coming on Thursday so I am in full on boat white tornado mode....
What took me an hours with soft scrub last time took almost no time at all.
I have used it on hulls before, cleaning the odd scuff or that brown mustache that you get when you visit the dismal swamp... Wow that stuff is amazing!
MaryKate "On and Off" - Hull and Bottom (http://www.amazon.com/MaryKate-On-Off-Bottom-Cleaner/dp/B0000AXNNI)
Craig-sounds great, but keep this in mind. Oxalic acid in salt water will wash the "Waterway Frown" off, like you used a paint brush and fresh paint. It's amazing.
Look for SavoGran wood bleach. Oxalic crystals
It has Oxalitic acid in it, a bit of detergent and is a bit thicker so it does not drip quite so much....
Best not to get it on any cloth.... Works great though!