If you use any electrical heat source use two. Put them on separate breakers. Hate to rely on a cheap bulb to protect your hardware. I have used two ceramic heaters. They each have a t-stat so let them fight it out. If one dies you are protected.

100 watt bulb would keep my engine compartment 10 degrees warmer then the outside temp

Bulb em and Hug those bravos for a month or two!!!!!!! No probs from there....your arms might get cramped a little!!!!

Light bulb would have gotten ya through the night ok just make sure the drain plug is in and that your light is susspended down low in the bilge (warms up the cold air at the bottom that way

Jon

My buddy's boat had 2 bulbs in his sea ray this winter sitting in the water .It froze and busted the block and 1 head . It got down to 18 just one nite this winter here in Mississippi,even sitting in the water i would have thought it would have been ok.He got lucky Boat US paid the insurance claim.Is it worth the chance?

Update:

Got back from LOTO,
went to the shop,
drained them, put it
back to bed,
now we get to enjoy
3" to 5 " of snow