My detail lady uses Bon Ami. It is made of egg shells and contains bleach but it does not scratch the gel coat. As it cleans, it polishes.
When I was pouring in the gas additive, the pour spout was defective and a bunch of red fluid spilled down the gel coat and onto the swim platform [gel coat, too]. I tried hosing it off with water, but the red stain stayed. I didn't have much time to mess with it, so I sprinkled Bon Ami on all the stain and left for the week. The next weekend, I took the hose and flushed the Bon Ami off. The red stain was completely gone. And I did not scrub, polish or wipe at all!