Snotter is right. Epoxy is very waterproof and looks nice when you first apply it, but it will not hold up to UV degradation and will oxidize and become chalky and dull much sooner than a polyurethane paint (which is not as waterproof and should never be used under the water line when immersion is a long duration or it will blister. It is ok if above the water line and gets wet. Since it is not submerged, it will not be adversely affected.