Has anyone ever actually ever looked through their sail window and seen anything useful? Almost all sails have them, but they're always too small to be worthwhile. I find I'm always looking around or under the sail, not through the window. They probably need to be twice the size and one panel higher (to account for heel).

For whatever reason, they do seem to make the sail look nicer, but they don't do anything.

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I use the window in the main to find the lay line for the bottom mark quite often. If the bottom mark is past the back of the sail we have gone way too far and probably won't make it with the kite up.

Tiger Mike

I think the window on my N20 sail is just fine. The problem I have with it is that its usually so full of spray that you need to wipe it down with rainex to keep it clear. I don't know if Rainex would hurt the windows though.

I am having trouble with that issue- overstand and then I find myself going uphill to the C mark!!!! not very efficient.
Thats a good idea though.

I think I would sorely miss them if they weren't there...kinda one of those taken for granted things. No, you can't see through them terribly well but you can see shapes.

I try to take note of what works and doesn't work for different wind/sea conditions as that does change our angle down wind. Not totally accurate but using the different letters as "brake markers" depending on the conditions seems to get me pretty close.

Anything more than 90 deg (which ends up in the blind spot usually is inefficient (for light winds) or just means I won't make the mark if it's honking.

Tiger Mike

If you ever try racing without the windows in mainsail and jib, you will understand "clearly" why they are there <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
At the starting line they are very good, and they are a real safety precaution on the course as it is easier to spot other boats on a collision course.
If you dont race, the windows are still great when passing boats or other objects. We sailed much of last season without windows in our main and jib, and really missed them. Our sails will definately have windows installed this season.