Depends a lot on where you are located. I assume you are in an area where the water does not freeze around your boat so that is good. Consider that the water around your hull is not frozen so it is above 32 degrees and will in fact put heat into your hull when it is below freezing air temperature. Not enough to keep waterlines from freezing but every little bit helps. Now throw in two bilge heaters in the engine room(always run both in case one should break). Then a few well placed ceramic heaters inside the boat. Keep a couple of ocillating fans going inside the boat and you are ready for winter on the Tennessee River. Now further north you may have to drain the engines and genset. Pump in pink antifreeze if a raw water cooling system. Put pink antifreeze in the freshwater tank. Pump out the blackwater tank. Close all seacocks including head. Good luck. We are thankfully able to run our boat all year and we have folks on the dock who can crank the genset if the power goes out due to weather.