Solid fuel heat
I've got a Newport 30 II that I live on and a Cole solid fuel heater that works fine. It takes a little while to heat things up but I've not had any problems with it. I always make sure there's no fire and the ash is empty before leaving the boat and I never leave the fire burning during the night when I sleep.
It has a small metal door that slides up and fire screen so the fire is visible that makes for a very cozy cabin.
During the winter there's nothing like sharing with friends a hot chocolate and kahlua during the evening with the fire burning or a cup of coffee in the morning while there's frost on the docks.