If unwrapped, the floor drains could freeze over and prevent water from draining overboard. Other than that, just growth on the bottom and as mentioned slippery surfaces. A short haul in the spring would take care of all that you would need to: bottom cleaning, paint, buff, wax, lower unit oil, zincs, etc. I guess that is one other precaution: most change their lower unit oil in the fall to assure there hasn't been any water entry that could damage the lower unit. I kept my previous boat in 1 winter and thoroughly enjoyed going to the marina, turning on the cabin heat, and tinkering/hanging out on the boat. I have used it (my old Sailfish) on nice winter days, going for a cruise. I only did this when the temp was above freezing and would allow the motor to drain out before it would freeze up.