Thanks for all the response on the propane heater idea for a boat with an enclosed engine and bilge. I e-mailed the "Mr. heater" company and they said that they do not support using the propane heaters in boats with enclosed engines & bilges as the propane is heavier than air and could cause an explosion. I think it is one of those things that you could get away with but the one bad day would be it. I'm looking to dress warmly!