For anyone who might have an interest, I put a propane heater aboard Cloud Girl, my 1985 M17 galley model, last year. Worked well during nights in the 30's (frost in the cockpit) where I sailed, at 8280 feet on Lake Granby, CO last season. The smallest heater was still overkill, but I don't need to crank it up, or use it long to get the effect needed (often just used the pilot light). One pound propane tank and regulator in the stern wet locker, single line run to the heater by the galley, only 2 connections that are easy to check. Yes...I handled the exhaust properly. I also am careful with ventilation. I don't sleep with it on either. Contact me off line if you wish; I could scan a couple of photos, I think. The biggest challenge was mounting it, which I did on an upside-down L-shaped sheet of stainless, anchored top and bottom. The space lost was no issue as I am a single-hander. I will be moving on to my next boat, a 1982 Cape Dory 25D, this season. I'm not ready to part with my little Cloud Girl yet, however. My last three seasons with her have been deeply satisfying. David Patterson