If you are looking for a product that truky cleans aluminum boats Purple Power Aluminum Polish truly works. it is a spray on spary off application that takes literally no scrubbing for most boat stains. It does contain acids so take all appropriate precautions when using. I swear this stuff works! I found it on the O'Reilly website and had it shipped to the store for around $13.00 fora gallon. My 12 foot aluminum boat will only take about 1 to 1 1/2 quarts to clean the entire boat.