I live on a small sailboat... and when I’m away from all the comforts, I found one thing indispensable, an old, sturdy cast iron hibachi, if you can find one. Some of the new ones they’re making are really garbage.
I found that when I was traveling, that old hibachi bolted to my transom fulfilled all my cooking, water heating needs very well. I’m not saying it’s the ideal appliance for cooking, but it will burn anything...when I was traveling, if I saw the beach with a lot of driftwood on it, I stuffed my cockpit lockers full of wood... as long as I used sun bleached well weathered wood, I never had any problem... an added aesthetic benefit is that if it’s evening and the fire has burned down to coals, the salt in the wood makes multi colored flames, very neat.
The downside is, if the wind is blowing in the rain is falling, you need that first cup of coffee in the morning, you have to learn how to make a fire in any weather... but if you love your coffee, you learn!
Is there another method besides gasoline and a road flare? I guess that method might not go over well on a sailboat. ;)
/johnny