One thing we always do is keep the chemical foot/handwarmers on the boat, (even though we have propane heaters) they could save a life under extreme unpredicted situations, don't cost much and right now is the time to stock up as Wal-Mart etc. stocks them by the thousands

I prefer the foot warmers as they're bigger, hotter and hold heat much longer which could mean a great deal if you really NEED them