Would the fumes be dangerous if I were to use an alcohol oven to heat the cabin occasionally?
Mark Matthews responds:
As far as I know, alcohol fumes aren't dangerous—just nauseating. The dangers from an alcohol stove come primarily from the alcohol spilling and creating a fire. If you've never had to battle a fire fueled by alcohol, it's a bit bizarre the way a liquid can spill everywhere and then start burning. Sometimes the flame itself is hard to see because it burns at a low temperature.
The other problem with your idea is the open flame. It's not so bad with well-ventilated areas, but any open flame down below in a sailboat is cause for caution. I once had a rough passage in which the contents of an open locker rearranged themselves. Little did I know that the toolbox had fallen on top of a can of WD40, puncturing it. When I moved the heater in front of that locker, whoom! My mate found the fire extinguisher and put out the fire (after giving me a good shot with it). The lesson is that special care has to be taken with all open flames on board a boat. And of course, you'll want to keep a hatch open a little to make sure you have enough fresh air circulating as well.
A final drawback to alcohol is that it puts out water vapor, which can create mold and mildew. That said, all the drawbacks in the world are canceled on a cold winter night when all you have is an alcohol heater! I've opted for a small electric model now that we're dockside. It puts out a dry heat, is cheap, and the convenience can't be beat. But living out on the hook is another story!