I wear one nearly all year -- I just hate being cold
I favor this type, with the glideskin on it.. its windproof also... so you have more warmth with less bulk. Also make sure it doesnt have a zipper in the back -- I have been burned buying a top with a zipper in the back that I didnt realize was there, and it isnt necessary and is annoying when you are driving the boat...
http://www.oneill.com/#/men/americac...ls_crew/black/