I've used that product on my wood deck and still find I need to re-topcoat it every 2-3 years to keep it looking nice. Even power washed the deck and did all the cleaning steps they require. Have had similar results using a premium Behr product that on fences is "labeled to last 8-years" ... well after 5-years of weather exposure and it looks like it need a re-coat.
If it's one thing I've learned on boats ... paint ONCE and you'll be painting FOREVER!
For boats and especially longevity, I don't think one can do any better than marine vinyl. I mean look at this ... 20-years old and put on a mooring in the salt 24/7 for all those years and the vinyl flooring is still sound and looks good! Carpet at 20-years would look like crap ... and is heavy!