NYC XYZ wrote:

Anything plasticy does... who doesn't use 303 or something similar
on their boats?

If it was hardshell plastic, I wouldn't bother. But being that it's an
inflatable I have...I don't want a hole to develop one day -- on the
water, no less!

I'd say 303 is a waste of money for a PVC boat. PVC outgasses and
becomes brittle after about 5 years, so UV damage is inconsequential
in comparison to that.

I do use 303 on the latex gaskets of my drysuit, and it seems to make
a huge different in longevity. I tried 303 on the nylon fabric of
my PFD, and it faded anyway, so its UV resistance might be overrated.

If you put 303 on a boat before going out, it'll wash off anyway.
Maybe it will keep PVC soft for longer than 5 years, but if that's so
I never heard anyone mention it.