Given what I know about running at night (30 mph, not so great), and what I think I know about your winter temps, not sure I'd trust much of what your seller said about winterizing... unless you'll be on the boat 24/7 with other heat sources running.
The whole regime is extensive and with details specific to your boat, and varies somewhat depending on whether you're storing in water
our out, but in very general and abbreviated terms:
- run potable (environmentally friendly) antifreeze
through your engines and then shut the thru-hulls
- ditto genset, if you have one
- ditto air conditioning
, if you have one
- run potable antifreeze
(aka pink stuff, RV stuff) through your freshwater systems (drinking water), "saltwater" (river, whatever) washdown systems, if you have one, hot water
heater, etc. This is the one where the system can be largely emptied with compressed air, and you may or may not need pink stuff at all except for your waste holding tank
. (A waste tank thru-hull should be closed, too.)
The light bulb idea is pretty good, though. Also, a low speed fan can help move that slightly heated air around, helps minimize condensation
. You could put a light and a fan on a timer...
If wintering in the water, you may need a de-icer... which usually keeps water moving enough that, along with the movement of the boat itself, means ice usually won't start lifting the hull
out of the water...