We lived in Philly last winter....
We lived in Philly last winter, and it was hard at times, but not that bad. The marina we are in has a bubbler system to prevent freezing, but it didn't work. Only 2-3 boats had the little electric motor with propellor, and those worked well. So we ended up having about a foot thick of ice around our boat. I would routinely go around the boat and break up the ice and shove it under the ice away from our boat.The good thing is, when it freezes, the water is dead calm, so no rocking.We used 2 1500 watt electric heaters. Most of the time we only had one on, but when it got really cold we would turn the other one on. Condensation was not a problem for us, because the little electric heater with the fan would dry the boat out. In fact it would be too dry, and we would get sore throats. The only problem is if the electric goes out, then you loose your heat. For this, I bought one of those propane heaters that take the 1lb. tanks, and kept it in my car trunk. I never had to use it, but it was there just in case. I returned it after winter. WE also had an electric blanket. We would turn that on a half hour before bed, and it would be nice and warm when we went to bed.I did add insulation to the quarter berth, because the heat was not getting back there. If I were to live on the boat during winter again, I would add insulation to the ceiling and walls, because most of the heat just goes right out, considering the boat is just plastic. BY the way our boat is 27ft pacific seacraft.If you leave the heat on all the time, then you shouldn't have a problem with using the water system on your boat. I would winterize the engine though. And leave any doors or places that have plumbing open to let the heat in. One big problem is, that the water on our side of the dock was shut off. The other side was heated, so I would have to hook up the water on that side and fill our tanks. BUt when it got really cold even the heated faucets froze, so I bought a 5 gallon plastic water bag from wal mart and would make a few trips to the bathroom and back to fill up our water. It was a pain in the A**. But it was only for a month or two.This year I took the boat out of the water, because I need to do some work on the bottom, and we won't have to live on the boat in the winter. Good luck.