We use Krud Kutter. Spray it on, let it sit for a couple of minutes, then wipe it off and all the dirt and 99.9% of the stains come off on your rag. Have a lot of clean rags handy, they fill up fast with dirt, etc. Use brush for hard-to-get-to places. We then power wash to remove any left over KK. Amazing stuff and it's FAST.
After the boat is dry, use Hobie Protectant or 303 on topside (except where you might usually step) and hull. Easier to clean the boat next time because not as much sticks to it anymore.