Took it out today to give it a wire brushing and shake out the dust. While it was in the winter sunshine I took a few pictures. As a couple of people have asked about it, here’s a detailed description.
It’s made from a short length of 2 inch copper pipe- which was bright and shiny originally but has now become a bit corroded and slightly pitted due to the heat..
The basic carcass, flanged copper ends, one fits inside and one out. The bottom one riveted, the top one brazed in place . A criss cross of smaller diam copper tube allow it to stand nicely.. the top has a little piece of 22mm tube brazed on for the flue outlet. I’ve added an extra layer of copper to make it a snug push fit into the flexible flue pipe.
The two copper sheet ‘hit and miss’ air regulators
The old army mess tin. Two little self tapping screws opposite each other hold things in place as shown below.
Assembled. Showing the 2 holes open
The 1 metre of 1 inch semi flexible metal flue tube push fits directly onto the heater, goes through the main vent hole , through a 3 inch hole in the inner baffle and then to outside through the deck vent hole.
There’s only one extra hole in the boat and I’ve never had any rain drips or splashing get through. The discolouration is due to some tar residue running down from the flue pipe.
The additional metal tubes are from a scrap vacuum cleaner The stainless one simply pushes onto the flexi one where is pops up though the deck vent when the stove is in use. The aluminium one has the end bent over. I ensure it’s facing downwind to give more suction so the fire burns bright.When sailing I don’t use the stove and stow the extra bits inside the boat, but leave the flexible section in place. I’ve fitted a CO detector inside the cabin
This cleat holds the handle of the mess tin firmly in its place within the boat. The bolt is longish and has a compression spring and washer behind the ply panel to keep the oak cleat nicely tensioned
To light the heater I half fill it with charcoal or tiny wood chips .Then squirt some meths (alcohol) inside through the upper hole with an old washing – up liquid plastic bottle and it’s usually burning brightly within 2 minutes. I use my fingers or sometimes a teaspoon to add more fuel Once going well I need to adjust the draught with the regulators to control the burn. The draught all depends on how much wind there is .Using some old pliers saves burnt fingers.
Charcoal is best if you want a nice gentle glow. That’s simple lumpwood charcoal without any additives . The ‘easy light’ stuff is to be avoided as the flue soon gets bunged up with residue and the smoke is evil
Wood chips burn a bit faster and give off a good heat but unless you have a ready supply, you’ll have to spend some time doing tedious cutting.
Although the heater is tiny and only holds a cupful of fuel it gives off a fair heat. So OK for raising the temperature a bit when one is sitting aboard during a chilly evening. I’ve blanked off the aft vent but leave the centre vent open and my research has shown that the airflow comes in through there to balance out what goes up the flue. Since the fresh air flows in around the warmish flue pipe before it gets to me it’s pre warmed – so to speak. The flue pipe is generally cool enough at the upper end to enable me to warm my hand on it. And I ream it out from time to time with an old car clutch cable, in case it’s getting plugged I’m aware of the dangers of this kind of heater. I could set the boat on fire or gas myself with CO if I acted unwisely.. I can assess and guard that risk myself, but please, if you do something similar assess the risk for yourself.
I’m sure that other materials and methods would also work. A slight enlargement , to say, 3 inch dia tubing would be warmer for a cold climate. and stainless steel would be a good construction material if you had it.