We have been using Opti-Seal on Boats with great results. Water tend to get on the boat and bake water spots on it. Black gelcoat is the worst. Opti-seal puts down a layer of protection unmatched by waxes. Water spots just wipe away with Opti-ID. Thanks David.

I guess I missed reading this when it was posted.
For the past two seasons I polished my boat with Poli-Seal and then topped it with Opti-Seal.
It was done in May of each year and seemed to hold up for the entire season. The boat was kept on a lift with a canopy, but it still got some exposure to the elements. It did get used about every week-end and for a couple of weeks of vacation as well.
The product seems to work as good on boats as it does on vehicles.