Hi Henry,

first of all, you are not alone with this 'improper winterizing'. My boat is in Michigan, I did the same and it is still ok. Luck, maybe... But if you have used antifreeze to winterize it, you have a good chance that the engine will survive the cold. Here is the reason: A) No thermostat is 100% shut, they all leak a little bit and therefore you probably got some antifreeze into the block as well. B) The water pump housing as the weakest part will be fine since you've flushed it with antifreeze. C) A shut down engine is never completely filled up with sea water so there is always some air. D) In Maine, I assume your water to be salty...

Good luck,
Chris