First, some historical notes.
There is a captain in Russia, Evgeniy Gvozdev, who made one single-handed circumnavigation in a 5.5 m sail boat – micro class racing boat.
Few years later he built a boat 3.6 m long in his apartment building kitchen, brought her down through the window and circumnavigated single-handed again.
Today, 4 years after his return he plans to go third time on a boat which should be 3m long. The boat now is under design. Going though the Roaring 40es is one of the options.
The question for today is – what type of heating device can be used on a boat this small?
It should not use electricity, should not consume oxygen from the cabin, and, ideally, should not use any fuel
. Granted, it should be tiny.
If you want to know more about captain Gvozdev, here is his website:
It is in Russian but I can post some material here in English.
He is now finalizing a book about his adventures. It will be published in Russian some time in the future.