Re: Extreme Cold
About 20 yrs ago, winter bubbling became fairly popular at our little sail club in Michigan. Since we were concerned about members jury rigging goofy heating within their boats, we made a rule limiting on board electric usage to no more than 100 watts.
We designed cheap convection heaters using a light bulb, for those who desired a little air circulation around things like their engine block. These heaters consisted of a cheap porcelain light fixture (the kind you see in closets or basements) mounted to a slightly larger piece of thin plywood for stability. Then cut out top & bottom of a large juice can to place over the bulb, which acted like a chimney. This was simply held in place a couple inches above the plywood by 3 or 4 thin metal brackets, probably cut from other juice can material. Not sure if this part worked, but someone came up with the idea of painting the juice cans flat black in an effort to absorb more heat from the bulb. We also wired these with something like a 10ft cord, so users wouldn't be burdened with trying to self wire the fixtures, or use short cords whose connections might fall into bilge water.
The juice can also provided some protection for the light bulb in case someone accidentally knocked it over. The contraption cost less than $5 but it's effectiveness was always questionable.
The more apparent problem using electricity in a bilge, is the obvious danger from an unexpected spark. Guess what, Gasoline fumes are heavier than air, and even the smallest amount will find their way to the deepest areas of a bilge.
That's why all approved marine electrical equipment is certified as "Ignition Protected". Our little $5 heater contraptions certainly were NOT "Ignition Protected" and neither is anything else you can purchase at "Home Depot".
Last edited by lightfoot; 02-05-2014 at 10:58 AM.
Reason: shorten the post