Boat Heater 1

I was going to wait until this was all done to post but decided following along would be more interesting.

We decided that the boat needs some sort of heat. Since electric, propane and hot water is out of the question it leaves a solid fuel heater as the best bet. I grew up with a house heated by wood and then spent many years building fireplaces so solid fuel heat is very appealing to me.

With that decision made the design process took awhile. We have a bunch of restrictions: cost, size, safety, efficiency and space. Cost is important in all our decisions and for this I wanted to keep it under $50.00. This was actually a hard restriction since it would be easy to design something and weld it but metal costs are quite high.

Next is size. Since the boat is small the heater can't take up much space but it also doesn't need to be huge and provide too much heat. I picked the dimensions of 15" high by 6" wide maximum. Safety is paramount on a boat when dealing with fire so all parts near the flame must be extremely well insulated. Efficiency was another tougher design area that I had to compromise a little on. The old school type of potbelly stove produces a poor amount of heat for the amount of fuel used. Finally space on the boat limits where the heater could go which was important for limiting what sort of shape and mounting the heater had to be.

This is the basic plan I came up with. The bottom black is a hydraulic cement base. On top is a 4" fire box encased in hydraulic cement. The two low white rectangles are air intakes and the longer white one is a secondary hot air intake going into the throat to promote secondary burning of the gases. The large dark grey area is the heat exchanger, this is the area I was forced to compromise to fit into cost and size restrictions. Making it more efficient ran up costs rapidly and the tiny size restriction also made it challenging to fit different designs.

Materials where kept simple as possible to keep costs down. Mostly various piping and hydraulic cement. Lots of cutting and fitting due to the small size (on a side note this design could be made slightly larger for under $20 using more common dimension materials).

The construction got a little hectic trying to figure out some issues on the fly but in the end it all worked out.

Rough design all done and ready for testing. I have done a few small to medium burns so far and have been very impressed with the amount of heat it can radiate for the small amount of fuel. Possibly larger air intakes or a taller chimney to promote a stronger draft could help but it will take more tests and trying out different fuel sources to know. More work needs to be done on building a mounting bracket and heat deflector as well as stove painting.
I will update later on as it continues to get tested and let you know how it works.