I live off the Chessie in Maryland and have been quite comfortable this (my first) liveaboard winter. I have three 1500 watt heaters set up on timers. They come on about 1.5 hours before I return from work and shut off a few minutes after I leave in the morning. I also have an electric blanket.
For the one real snow, I shoveled the side deck and the dock and put salt on the latter.
That does nicely for now.