Peter Bennett wrote in
news.com:

I think the best solution for his heating problem is a small Espar or
Webasto diesel hot air furnace. He did mention that he has a Force 10
propane heater. The one I had one on a previous boat was a
bulkhead-mounted "fireplace" with no provision to circulate the air.
When I stood up in the boat, my head was cooking, but my feet were
freezing.... That sort of heater needs a fan mounted above it to
circulate the heated air.


This is the best idea, but there's no room on the small cruisers for it.
Lionheart had a fuel oil forced air heater installed in the port lazarette
when it was built. By the time Geoffrey got it, the heater was all rotten
inside and he removed it to make room for the aft cabin heat pump, which is
more important in Charleston. It looked like the salt air had simply
consumed the diesel heater's steel combustion chamber. It was totally
rusted out.