Frankly I am looking for something really small... something to just take the edge off.

Down to 50f, I have found the cabin quite comfortable by just closing it up at night. So I just want something to take the edge off down to 40f... anything lower than that, I am not likely to be out sailing.

The smallest heater I have found thus far is the Dickson Newport... suitable for a 30-36 foot boat, and needing 12volts to run a fan, and a 3 inch flue.

Origo makes a small alcohol heater... some 5200 BTUs... anyone ever use one?