Agree that cotton retaining moisture is a killer in cold climates. The most brutal I have experienced is surprisingly during the summer when baked by the sun then after sundown the dampness chills one to the bone. Day sails are one issue but longer duration voyages are another matter.Honestly, I generally wear cotton turtlenecks in the winter because they feel better next to my skin and I have a lot of them. But I will wear synthetics if I feel there is risk of getting wet. I only wear synthetics when skiing, because I know I will sweat. "No cotton" is one of those rules we all know, and then break when we feel like it. Pretty funny, actually. That said, I've gotten wet in cotton enough times to understand the roots of the rule. It's a good rule.