Arm & Hammer Scrub Free Bathroom Cleaner with Oxy Foaming Action. It is less than $5 a bottle at my local grocery store. I have a 31 year old bass boat with a white hull. When I purchased it, it look like it had not been cleaned for years. I tried test spots with Simple green, vinegar, toilet cleaner, to no avail. I then tried this shower and tub cleaner, and it took the stains out very quickly. Although it says no scrub, I still used a stiff bristle scrub brush to work it in and spread the foaming action around the hull to prevent streaking. I got my hull clean in about an hour and a half, and I am pumped to know I do not have to spend a lot of money on a "marine" product for this issue.