Jinx,
Go to your grocery store or supermarket, or hardware store and pick up some
"iron out".
http://www.soap.com/p/super-iron-out-rust-stain-remover-66639?site=CI&utm_source=CSE&utm_medium=CPC_S&utm_ campaign=Google&utm_content=pla&ci_sku=SMT-004&ci_gpa=pla&ci_kw={keyword}
Use a sponge to wet the area with the rust rings.
Put a bit of the iron out powder on the sponge. Put the sponge on the rings and rub it enough to be sure that the area is well covered. Leave it alone for 5 minutes. Take a bucket of clean water and rinse the area, and you will find that the spot is gone.
The rust in the spot combines withe the chemicals in the cleaner to transform the iron into a water soluble substance. Then, water will rinse it away.
By the way, Iron out, works well in a washing machine for whites, that might have a slight or gross yellow or brown stain from iron.
Iron out will also remove iron stains in a bath, sink or toilet as well. Just get the area wet, and then use the same technique.
I always keep a container of Iron Out in my boat - along with a pair of heavy long rubber gloves. When using Iron Out, it is a good idea to use the rubber gloves to protect your skin from any chemical reaction.
By the way, when I bought my boat, the manufacturer recommended Iron out for this very thing.
I keep the iron out in the boat, so that any time that I have been in a body of water with heavy iron deposits and find a brown rust water line on the boat, I use the cleaner to remove the rusty water line. I spray down the boat, go over the line with a sponge filled with Iron out, and by the time I get around the boat, go back over the boat and spray it off. The rusty water line will be gone.
I also find that Iron out works very well for hard to remove general stains on the fiberglass. I always keep a couple of fiberglass scrubees in the cleaning locker. When cleaning the boat, if I have run into a spot that won't come clean, I just wet the area, dump some powder on the scrubee, go over the stain a few times with the scrubee, and the spot is gone.
Take care
REW