The easy way is to scrub it by hand and just wash the dirt down into the bilge with a hose. Takes a long time to dry, though. I use my carpet machine, pull the seats and clamshell and run it right in the boat. Use the hand tool for the corners. It cleans up pretty well.
What Duane said... Instead of the regular hose… I run a hose from my hot water tank. Sprinkle some Oxy Clean powder around and start scrubbing. Smells nice once it’s dry. The hot water will also help clean out the bilge.