The best product is "On/Off", you can find it at any west marine or boat store. It will make the fiberglass look like new but you will need to wash it with soap and water afterwards as well as apply a fresh coat of wax. It will remove any organic stains or rust stains, make sure you wear gloves though, it's potent stuff.

I second this one. I tried and it it worked great with very little elbow grease.

If you don't want to scrubb get some Attwood or starbright hull cleaner. Brush it on with a soft brush and it will eat the stain right off.

I ended up using "the works" and it worked pretty good. Sorry for the ignorance but do I need to use a boat wax or can I also use a car wax?

I use 3M restorer wax. Pretty much anything 3M is good. Car wax will work but you will have to reapply it more often.

"The Works" will eat rust off, very little scrubbing unless its real bad ..... Good stuff for keeping your boat clean.

Been using it since 1997.

Cheap, efficient and "It Works'" !!!

Thanks everyone for your info. Greatly appreciated.