Nautical ease makes a really good one specially formulated for fiberglass. I think were going to be selling this in our store too. Here is a photo:
And the product description:
This special formula enables you to finish your boat or car with a clear, smooth, hard coating which can only be described as glass like. It is the most easily applied and buffed off marine finish on the market today. It will not yellow, chip, peel or crack regardless of how many applications you apply.
NAUTICAL EASE POLISH reduces friction, frequently increasing speed and efficiency, helps [censored] barnacles, algae and resists salt water. As a polish/cleaner it easily removes white haze from oxidation, which is very common in the marine world, without harmful abrasives, as it polishes.
This formulation is very different from all waxes and other products on the market today.
I got a box of stuff from nautical ease and recommend their entire line.