Eryka...where are you???
Chef - Spent most of July in Canada. Couldn't really post about it in my blog (for obvious reasons, who's going to write in the local paper that they'll be away from home for several weeks
) But do want to write about it now that we're back; great cruising. And cooler and dryer than we heard it was here!
Hard to think about winter and heating yet, but here goes. I don't know that we have the "best" method, but I do know that we have a method that works in the Chesapeake, refined after 8 years of living aboard in Annapolis. Actually I think the "best" method of heating is to take your boat to Florida, the Bahamas, or the Caribbean for the winter, but I don't think that's what the OP is asking.
Our marina, like several others in the area, doesn't bill individually for electricity, so that is a factor in our cost decisions. We use an oil-filled electric space heater (the kind that looks like an old-fashioned radiator) in the main cabin, and a pair of small ceramic heaters one in the head and one at the toe of the V-berth. Our mast is keel-stepped, which means its a giant heat conductor - or cold conductor in this case. We wrap the below-decks portion with insulating material to minimize heat loss. Reflectix (the silver bubble-wrap looking stuff from Home Depot) is effective, efficient and easy to work. We also have a Webasto diesel heater that can heat the entire boat on the 1/2 setting - for if we're at anchor, or if there's a power outage. As others have mentioned, condensation is an issue in winter here, and the drying effect of these heaters is an advantage.
We tried tarping over and shrink-wrapping the boat; didn't seem to help the heating all that much, and we don't have a headliner, but the cover needed maintenance after every wind/snow storm, and it kept ALL the moisture in, making the condensation issue truly horrible. We settled for just fully enclosing the cockpit, giving us an airlock and cool storage room.
Pappy, feel free to PM me or email me (my email is just my screen name @att.net) if you want to chat about living aboard here - we really do love it!