What's your location? I would think pretty much anywhere north of the FL panhandle and you're in need of winterizing. Even south of there it's not completely out of the question to get a cold snap for a few days.
Water freezing will crack an iron block. Water doesn't move anywhere when it expands. It expands in place.
You'll have no engine, no boat, and a huge bill for a few months next season if you skip it.
Hopefully by now the point has been made. :)

