Even though it's currently 46 in Dallas...

[Spiderhole]

...call me paranoid, but I don't trust the weather service. It snowed 5 hours to the North of here yesterday. It's close enough that if it were to drop I wouldn't feel comfortable with water in the system still. I pulled the plugs on both sides of the block on my 4.3L, pulled the lower plugs on the exhaust manifolds, and pulled the lower hose off the water pump. It's supposed to climb back up on Sunday, but I would will still sleep better at night and it only took 10 minutes.

 

[alldodge]

Assuming the boat is on a trailer and not in the water.

It would take temps to go below freezing and stay there for several hours to do damage. A 40 watt light bulb in the bilge will keep the motor toasty warm