The interesting question is, how well does that coating "keep" the UV from attacking the sealant
, as opposed to mitigating the rate of deterioration.
I know of one case where the window started to pop within ten years, despite the UV-protective coating having been applied correctly, and remaining intact.
The case I like to keep in mind is the situation where the boat is temporarily keel
up, and something like a battery
breaks loose and tumbles across or into a port which has no mechanical retention.
I would certainly have strong storm shutters ready, on any boat with such a detail travelling offshore
, and they would be of a type which kept the water
out in the absence of the port, rather than simply being intended to bear the brunt of external impact, as some shutters do.