so the UV protector on the Sunbrella still allows UV to penetrate through to what ever is under it? That would require a new sail cover every two years.........interesting.

So in summary, the North 3DL main is a fragile sail, not really suited for a marine environment or at least a very long life in a marine environment. I guess this is another example of life being full of compromise. If your really need the 10ths of a knot the sail gives you, the compromise is throwing boat units at sail covers every few years? Personally, I would never appreciate the sail so would never spend the money for either the sail or the multiple covers....but that's me.

Kinda reminds me of the story I got from Interlux Technical service years ago. "You're using this marine paint outdoors, in a boat yard, where the wind blows and the humidity changes? There's the answer, that's why you can't get a decent finish. In order to use that ($20 can) paint, you need special brushing liquid at $18, thinner ($18) and $26 badger hair brush. It would be better if you could just move the boat indoors." So we have marine paint you can't apply in a marine environment.