This is our 4th winter aboard in Newport, RI. We also shrink wrap with the translucent plastic with a PVC support frame. We heat with a reverse cycle heating unit that works until the water dips below 40 F (end of Dec). We bought several small electric space heaters over one larger one to give us flexibility. We insulated the hull with foil sandwiched bubble wrap that you can get from Home Depot. We have a fully enclosed cockpit and I rigged an exhaust fan to suck air out of the cockpit thru a dorade into the main salon, taking advantage of the tropical heat (90*F) on deck during the day. We also have a Force 10 propane heater we use only when awake. Our marina uses bubblers to circulate the water around boats and pilings. This does a pretty good job of keeping ice away from the hull. I am not sure it's necessary. Occassionally I have to break ice up (11" thick 2 winters ago!). We bought slip on crampons to make walking on docks more secure in icy conditions. Several people have slipped off the docks and drowned here during the time we've lived aboard. As mentioned water is shut off in the winter and we have to fill up every week or so by running hoses from the heated lavatory. This has become something of a community gathering, as we all fill up on Saturday mornings. You need to "walk the hose" (making sure all the water is out) after use to keep it from freezing. Woe to those who don't walk the hose and let it freeze solid! We thought that we might have to abandon ship when storms roared in, but floating on a frozen bay greatly limits the motion! Here's a pic of me breaking us out several winters ago. Over all we've enjoyed the winters but not as much as sailing.