Originally Posted by james.mileur
Nice picture. I bet a 60w incandescent bulb in a Walmart plastic drop light cage would be more than adequate for the coldest night. Maybe even 40w. 12' extension cord to the outside outlet on the starboard side or to the power post.
Uncle Bob could probably provide the heat output, battery drain rate on the inverter if boondocking, and the parts list and specs if you want to construct a photocell/temp sensor box with diodes, MOFATs, widgets, and a framatz converter. He's my hero.
(how can I resist diving in )
Find a 12V
heat strip or use an automotive lamp.
Basic math is not in your favor:
36 W is 3A at 12V
3A for 24 hours is 72 AH.
Group 24's will do that for a day before you need to recharge. Group 27's for a bit more than a day.
Drop back to 3.6W and you can run for 10 days.
Except .... battery capacity drops when it's cold. Hmmm .... so cut that all in half if you intend to run in the cold on batteries. Don't even think about the inverter ....
Quick and dirty approach:
Stuff some insulation between the "door" and the plumbing. That will keep it from getting as cold as fast.
If you are not running shore water, blow the lines out with compressed air. If you are running shore water (and shore electric) get a piece of heat tape and do both the water hose and the enclosure with the same stuff.
Lots of strange ways to go ....