I had a solid fuel "Tiny Tot Stove" on the 38' sailboat we built. The disadvantages were: getting fuel, Stowing fuel, (We used drift wood, downed forrest wood, coal and charcoal.) There were ashes to remove and throwaway, and potential for sparks out the stack. After that experience, we did not bother to consider solid fuels again.
We used a diesel Dickenson on the 62' pilot house sailboat we cruised for 4 years--Calif. to the Med, Baltic and back. Problem was getting heat from one part of the boat to another, so we used fans, some help. Also it was very hot from the stack and. caused wood ceilings to shrink. We put a fan to cool--and move heat around the lower saloon. That was our primary source of heat during a winter in Norfolk VA when the temperature got down to 14*F. Although it was a drip pot burner, there was a pump to get diesel from the main tanks to the burner, and gravity could not be used- No use when under way--longer stack required than just the several inches out of the deck.
We used a "Pro Heat" 45,000 BTU forced draft, fuel injected diesel hydronic truck heater (circulated a liquid through copper pipes and small computer fan driven "radiators" in each cabin)--liquid was easer to pump thru the boat than running ducts, which would have to have been at least 4" and better at 6" throughout the boat. That could be used when underway under power. It was the best, since heated the boat fairly evenly. We could also pipe waste main engine heat through this same system for when we were underway. No back drafting because of forced air-but a lot of electrics: Low pressure fuel pump from the fuel tank, injector high pressure pump, air compressor,
forced draft exhaust,
The equivalent would have been the Eberspacher Espar Airtronic Heater or Wabtsco forced air in the C Dory. Although there are fairly small circulating water heaters, none are small enough.
And the vulnerable Wallas stove/heater running on diesel.
