This boat is a poster child, the upper portion of the enclosure covered for a time, then niether part covered. The lower portion has become barely translucent:
Often the bird dropping are an even larger problem; the vinyl must be cleaned every trip and residue that sits for more than a few days etches a permanent mark.
The covers on the fixed windows (polycarbonate) have cause no additional scratching, have slowed UV damage, cool the cabin, reduce window
cleaning, and reduced scratching. Simple enough.
But what to cover the soft windows with? Concerns abound that without some padding or lining the canvas will eat the vinyl whole, perhaps worse than UV sun exposure. Others use plain Sunbrella with success. I've taken a hand full of Sunbrella, rubbed it on Strataglass and seen no damage.
On the right is a weather beaten 16-year old cover, the edging eaten
right off by the sun. Under it is pristine 16-year old Strataglass. The rest of the dodger has been replaced twice and is not as good.Could the skylight have been better protected? No, I don't think so.
On the front windows I have a non-contact cover. It was simpler to build and seemed like a better idea... though I don't know that it was. The front and side windows are already far worse, the result of scratching from rolling and kayaks sliding by.
Would a lined Sunbrella cover be better, as many have suggested, or would it only hold more grit and be more prone to scratching? Would it be like cleaning the glass with a grit-encrusted rag? Always puzzlement. I pretty sure plain Sunbrella is the answer.
Or not to cover....
In very windy anchorages I've been told that covers can flap and scratch the vinyl. No question, if you take Sunbrella and rub it against vinyl, at acts like a fine rubbing compound. Clean cotton, by the way, will not do that and so it can be used for cleaning and polishing, but as a cover it wouldn't last and certainly wouldn't stay clean.
No universal answer, it seems.