Here’s a story I heard on a boat yesterday while fishing in a chill. “Greg” decided to go fishing for blackfish on a buddy’s boat one day and they ran a few miles outside the inlet. The temperature had dipped below freezing. Offshore, Greg noticed white smoke coming from the bilge hatch. Water in the Automatic Bilge Pump had frozen solid and the motor overheated trying to unstick itself. It sparked, causing a fire to jump up the wires towards the fuel tank. Fast action with the fire extinguisher saved them from an explosion and/or immersion in chilly water.
Anglers are most likely to push the margins of weather. Running a boat in extreme cold is not a casual thing to consider. Take heed of all that cold can do before leaving the dock.
First, think of all the places on board where water could freeze overnight. Water expands as it freezes, and could crack through-hull fittings, cause seacocks to jam, and harm your engines or internal systems.
Tell someone where you’re going. And when you plan to be back. See above; if you get in trouble the faster help can find you the better. This would be a good reason to invest in a SPOT Personal Tracker.
Alcohol does not warm you up; it will make you cool down more quickly and, of course, impair your judgement. Save the flask for after you’ve driven home from the marina.