I tried it along with a couple of friends and it didn't seem to work any better than other polish that I have tried. The only thing that we didn't do was put multiple coats on as the directions recommends. Kind of expensive. Left a nice shine on the hull, but did not seem to make any difference with the yellow stains. I had to use hull cleaner to get the stains off.
I have tried a different polish just recently. Bought it at a local Auto Zone. It is called Liquid Glass. Says it is made for any metal or fiberglass. Specifically says can be used on boats. I used it years ago on a Vette I owned. It goes on very easy. I put 2 good coats on the boat and let it bake in the sun between coats as it says on the directions. It put the best shine on the hull of any polish I have used and cleans up an shines all of the polished SS better than any product I have used. We have been out 2 or 3 times since we polished the boat and no stains and what has gotten on the boat has just lightly brushed off. Might be worth a try.