I have been wiping & cleaning with a pressure washer using soap after every outing with my boat & the crud on the hull just kept getting darker & darker. I boat in the dirty Ohio river & I can see crud building up on the hull causing a bath ring around my boat. After winterizing I tried just about everything to clean but nothing worked, a buddy told me to use polishing compound & a drill with a bonnet on it to buff it off. Knowing that's abrasive I didn't want to start that. I had tried the Star Bright hull polish but that wouldn't cut the crud. I talked to a woman in Walmart that said she & he husband have a boat & she buys this for her husband to use. This stuff is wonderful, just spray let it cut the crud & wipe it off. This stuff is so great everyone needs to know about it.