I searched the archives and found some brief info of spray skirts, so I am looking for opinions on how much of an actual  advantage they offer in wind and waves?  Lake paddling only, not whitewater.  I know they help, but by what kind of margin? 
I will be making only my 3rd  solo trip this year in mid September.  I bought a set of beautifully made and fit Cooke covers for my solo canoe years ago, but never encountered enough bad conditions to use them.  At least part of my trip this year will be on bigger water. So I do not want to be over confident with them in use, only to find out the difference is minimal.
Yes, I know, find some bad water locally to test them.  That does not seem to work for a variety of reasons I will not bore you with.

Thanks for the help.

MossBack

I had Dan Cooke outfit my Prism with a spray skirt several years back.  What Fallguy says about "warmth" is definitely true.  That being said, I haven't really used the skirt all that much since most of my travel occurs during summer months.  I don't need that warmth and I don't really care all that much if it rains.

I think the value of spray skirts for lake-travel-mostly canoe campers can be found primarily in the shoulder seasons.  It's colder then and staying dry & keeping your gear dry is more important. 

I suspect there is something to be said for being more aerodynamic but I don't think I'd buy a skirt with additional paddling speed in mind.  As far as dealing with waves in big water, well, fortunately I haven't had the "pleasure" yet of a real test when the skirt was on.  There's bound to be value there, if you know the odds of big wave splash are significant.

My biggest issue with the skirt is how best to handle it during portaging.  No matter how you deal with it, it consumes more time and can get a little frustrating during a multi-portage trip.  I'm sure there are more effective techniques for managing it than what I use.

My bottom line: I put the spray skirt on when I solo in the months of May and October... and maybe September.

Jimbo   

Been a long while since I took a science class, but if the wind is flowing OVER that canoe cover, doesn't it exert some downward force to give some added stability in choppy water?

My canoe skirt is plaid.

The Bernoulli effect on an airplane wing certainly lifts the plane up by creating a low pressure area due to the difference in the speed of the air flow.  But a canoe probably does not lend itself to the Bernoulli effect for several reasons.