The purpose of this project is to design and mass-produce kits for a floating tiny house that can sail. It combines high-tech modeling and fabrication and low-tech assembly that can be carried out DIY-style on a riverbank or a beach. This boat is a four-bedroom with a kitchen, a bathroom/sauna, a dining room and a living room. The deck is big enough to throw dance parties. It can be used as a river boat, a canal boat or even a beach house. It's rugged and stable enough to take out on the ocean.

Wednesday, May 16, 2018

Marine Russian Stove: Heat Storage

This is the next in a series of posts devoted to solving the problem of fitting a traditional Russian stove aboard a boat. It is interesting to see how the concept evolved based on feedback from the readers, following the same pattern that the entire Quidnon project has taken, where half-baked ideas eventually turn into fully baked ones based on good ideas contributed by knowledgeable, experienced people.

The reason for the name is that this stove will do everything that a traditional Russian stove does: it will provide space heating, a warm place to sleep, hot water for washing, heat for cooking, and can be used to heat rocks for a sauna/steam room. But the Russian stove is a massive piece of masonry erected on its own foundation, and masonry doesn’t belong aboard a boat except perhaps as ballast. (The distinctive red bricks out of which much of Boston was built had sailed over as ballast aboard British ships and were so plentiful that the colonists took to paving sidewalks with them.)

And the reason for including not one but two marine Russian stoves in Quidnon’s design is to make it possible to travel and live aboard a Quidnon in Russia, and overwinter aboard in places where rivers freeze solid and temperatures can stay below -20ÂșC for weeks on end, but where there is generally plenty of firewood available. Quidnon’s hull, made up of 3cm or so of plywood and insulated with closed cell foam and radiant barrier, and hauled out on a riverbank, replaces the traditional log cabin. To keep it warm, the marine Russian stove replaces both the traditional Russian stove and the stove used to fire the Russian banya (sauna, if you prefer Finnish).

On board, all of these many functions provided by the use of masonry in a traditional Russian stove have to be arranged for in other ways. Space heating is provided not by radiant heat but by forced warm air; hot water is produced using a heat exchanger; cooking (and heating up sauna rocks) is on a stovetop rather than a pizza oven-like vault. (Heat can be directed to the stovetop—or not—using a baffle.) With the stovetop shut off the stove will generate minimal radiant heat, allowing its heat output to be piped and ducted to where it’s needed. (Who needs extra-hot galley or heads?) Heat is stored in the hot water tank instead of within a masonry structure. In a wood-fired stove, masonry can get four times hotter than water can get under atmospheric pressure before turning to steam, but water has about four times the heat capacitance of masonry.

Most of these concepts have been worked out already and described in the previous posts. The only new element I have added since then is a water-to-air heat exchanger around the hot water tank: forced air will be made to flow around all six sides of the water tank. Thus, it will be possible to fire the stove in the evening long enough to get the water hot, then use that heat to produce warm air all night. On colder nights this may not be enough to keep the entire cabin comfortable, but with the hot air ducted to where people are sleeping it will at least keep the berths warm: a boat-sized hot water bottle. The position of the hot water tank is directly below the stove itself, keeping the runs of plumbing very short and placing the mass of the water low down where it will add to the boat’s stability. The hot water tank is integrated into the structure of the stove, and this will save on materials.

This stove will ship as a kit consisting of sheet metal shapes plasma-cut and bent on a brake so that they can be assembled using hand tools. The kit will be designed to pack flat efficiently, and will include all of the plumbing, hardware, insulation, sensors and electronics (a programmable controller for regulating the flow of fresh air from outside, for dialing in air and water temperatures, plus an alarm for when it’s time to add firewood) and a thermoelectric generator to power the control circuitry (and for charging phones and laptops).

This stove is a marine stove, meaning that no effort will be made to certify it for residential use. Some locales regulate wood stoves more strictly than others, and it’s up to you to figure out if you can (or have to) use it legally. Keep in mind, this is a stove that two people can lift and move (with the water tank drained) and so it doesn’t have to be a permanent installation. If you have a fireplace that’s grandfathered in, then you are probably good to go. If not, you’ll need to install a flue somehow. It may be a bad idea to use this stove in an urban or suburban environment in what currently passes for “developed” countries (i.e., litigious and riddled with bureaucracy). But there should be few issues with using it in a rural environment, especially on a homestead.

If you use it on a boat, then the standard marine disclaimer applies, which goes something like this: “Please check your local and federal regulations concerning the use of wood stoves aboard.” But it should, by its design, pose many fewer risks than most marine wood stoves. It will be insulated with rock wool all around and remain only warm to the touch even when fully stoked, making it safe to use around toddlers. It cannot be made to overheat the water, and will automatically shut down the hot water circuit by emitting a puff of steam. And it will regulate the burn rate as needed by adjusting the amount of fresh air pumped into the combustion chamber from outside. The firebox will remain completely sealed off from inside air (except while adding wood) minimizing the chance of CO inhalation. The kit will carry product liability insurance, but anyone filing a claim would have to answer a simple question: Did a qualified marine surveyor approve the installation?

I hope that this stove design will turn out to be very useful both on and off boats. It can be used to heat a cabin in the woods while providing cooking and shower water. It can be used for summer cooking, canning, and to keep greenhouses warm during cold spells by piping in warm air. And arriving, as it will, in the form of a lightweight, flat-pack kit, it will be possible to install it in roadless locations such as cabins up in the mountains, where hiking in a masonry or a cast iron stove would be too difficult.

So, how many of you would consider buying this stove? And how much would you be willing to pay for the kit to build one? It would be very helpful to have some indication of the level of interest before committing resources to working out the detailed design and organizing the fabrication process. Potentially, the sale of kits for building this stove will offer us a way to financially bootstrap the project. It will also allow us to get our feet wet with managing the logistics of producing kits, so that we can learn by making mistakes that are small and cheap rather than boat-sized and very expensive.

For those who have been Quidnon fans for some time, I hope that you will find the bootstrapping approach appealing. I see it as a potential way to keep the emphasis on building some excellent boats rather than on hurrying up to making money to pay back investors.


  1. I need something similar for a very small unpermitted house in a rural area. I don't like most of the options on the market because they all seem to lack one or more of the essential functions (no water option, ect.) And they are mostly out of the budget. I'm very interested in purchasing a kit.

  2. Dear Dmitry,,,
    Assembled using a few hand tools--including a welder, I'm guessing? If not, how is the water tank and stove made air and water-tight? Also, how is water-heating efficiency maintained when scale builds up from heating unsoftened water? (I don’t recall a deck-based rain-water collection system.)
    I absolutely love this whole project--the design process and the outcomes. The relatively few questions/problems I've had earlier have been largely addressed, but with new iterations, more arise.
    Were it my project, these stoves would be 'cold climate add-ons' instead of integral to the completed boat. I already have a travel trailer with full kitchen w/3-way refridg/freezer, gas stove/oven, sink etc., bathroom with shower, sink, water storage/heating, a-c and a gas space heater. The value of the trailer varies from negative to very little, depending upon the prices of gasoline and scrap metal, so parting it out and reapplying the as-new components into a Quidnon seems very cost-effective, especially for me, who has no intent to overwinter in the frozen North (no matter how very desirable exploring Russia is to me).
    What I'm hoping for is are multi-level, easily-upgraded Quidnon offerings—one more easily purchased by those of us not squeezed into your cold-weather target-market. Level one might be a bare-bones ready-to-assemble insulated hull; level two would include masts/sails w/complete rigging. Level three could be levels one and two completely outfitted for moderate climate use and level four for the full-blown, over-winter-anywhere model with all the bells and whistles. All available at different price points, and easily up-graded if/when needed. I believe that if your product line was increased thusly, so would your sales, with very little, if any, increased costs.
    The stove, depending upon price and assembly difficulty/costs, might be a great seller for those building a tiny house, or those of us who wish to upgrade to a ‘modernized’ DIY Neo-Russian heating/cooking system. My uninformed guess on price-point is in the thousand dollar range, but I truly don’t know. It seems that most choosing to live in a tiny house often don’t have a lot of money to spend, but again it is pure speculation from me—and nothing more. As far as using the stove sales to finance the rest of the venture, I was under the impression that financing was already largely in-hand, and after your initial boat was built and tested/proven—that production of the fleet would commence very quickly.
    Lastly, does the complete hull components include copper sheathing up to the waterline, and if so, how thick is it and how is it attached?
    Keep up the great work Dmitry. It is a fascinating project that I’d love to see completed/be a part of, presupposing with my existing health concerns, I get to live that long.
    Best always,,,locojhon

  3. Hi Kara,

    Thank you for your interest! I hope a few more people chime in, and then I'll start working out the details.

    Locojhon -

    No welding will be required. All welded parts (and there are very few) will be pre-welded. The structure will be made watertight and airtight using gaskets and fastened together using bolts and metal bars.

    These stoves are definitely add-ons. One of the options will be a bare hull with no amenities of any sort.

    The crowdfunding yielded barely enough money to come up with some stove kits, definitely not enough for a whole boat. Other than bootstrapping, the only other option is equity crowdfunding (i.e., debt) and I don't like debt.

    The copper sheathing will be cut to specific overlapping shapes scored on the inside surface to hold glue, glued on using an epoxy-based adhesive and fastened using bronze screws driven into epoxy-filled plugs. It will be standard 0.55mm roofing copper with thicker 0.69mm available as an option for greater longevity and abrasion resistance.

  4. I would be interested in such a stove for a summer kitchen, and I could perhaps pay as much as $1000 for such a stove. This is a wonderful project.

  5. This is a great idea. It would have use in virtually any living space. Heat, hot water, spa, cooking surface, etc. It is the Swiss Army Knife of stoves!
    Any idea how much the kit for the "Victorinox" will cost?

  6. Around 700 USD seems like a good price.

  7. If any of you readers are having trouble grasping how the system works, it's important to read the previous blog post.
    What gauge is the metal? Is it sheet steel or stainless? It would be great to submit a prototype stove to a month of daily use with different burn times and temperatures. How well does the firebox wear over time?
    Like Quidnon, this stove is a clever design and could be very useful to many people. I believe these things will need to be seen to be appreciated and could very well gain wide appeal over time.
    Locojohn's estimate of $1000 seems in the ball park to me, but hard to say.

  8. Dmitry, I've been following this for a while, and like many others, I love the scope and vision you bring to your project. It seems like this stove is a stand alone product that works for Quidon, but also in other applications, so perhaps another crowd-sourced initiative to road-test the stove in a cabin environment might be warranted? I agree with Pantalones Frescos that a road-test for this design would be wise. Market Quidnon while marketing a tested "Marine Russian Stove" would be effective.

  9. I'd be interested in one to put in the far end of my house from my existing cast iron woodstove. The cost of the kit itself is less important to me if the nature of the exhaust is limited so that a 3" pellet stove flue can be used, as they are cheaper than a class A woodstove flue. I'm considering a pellet stove for that part of the house for that exact reason.

  10. Very cool project! If I had my way and the world was a different place I would do this kind of thing all the time. Actually I did for about 10 years or so.

    This stove might benefit from some strategic insulation. I understand that you have air space and water flow for insulation but there will inevitably be some times and locations where extreme heat is concentrated and that could lead to failure. There is fire brick that comes in 1" thick pieces. There is ceramic wool that is fantastic for design as it is highly heat insulating and can be easily shaped to fit where needed. There are also woven fabrics that are very high temp resistant. You probably already know all this and about rtv silicone but I just want to throw this out there.

    I have a couple of tent stoves that I have modified and use for different things there might be some useful info there.


  11. In agreement with all previous comments. Count me in.

  12. Jeff, the stove, as explained above has a layer of rock wool insulation surrounding a sheet steel firebox. This is contained using sheet aluminum which shouldn't be too hot to the touch during operation.

  13. Pants - Insulation keeps outer layer cooler but in turn focuses heat on inner layer increasing the need for refraction in the firebox.

  14. Over on another blog, an interesting discussion on stoves.

    How To Safely Heat With Wood, by W.S.
    June 1, 2018

    In the comments, someone mentions a Russian/Finnish TWIG Stove.

  15. The surface to volume ratios of the heat storage tank-As with Masonry 30 cm thick=12 hours of heat storage.
    High latitudes-You would want "thickness" of 50cm for 24 hour "Thermal flywheel".
    So a 50-60 cm diameter cylinder of the same height for storage.
    If the thermonic generators are up to a 10 watt load-circulation pumps would start only when heat is produced in the exchanger and if that is in the (vertical flue) draindown to the storage tank could be automatic.
    The heat Storage tank as well should have a bottom drain to lay up the unit without frost wreaking it.
    A separate larger tank and lower temperature
    heat harvest storage could function as a Japanese soak tub in winter layup and be a storage well for say bags of potable water ect when cruising.
    Todd Millions

  16. The heat exchanger water flow seems backward. The drawing has cold water intake at the top and the hot water outlet at the bottom. But heat rises; it doesn't fall.

    I made a similar system that used a coil in the stove's firebox, with the cold water intake at the bottom and the hot water outlet at the top. That, coupled with an elevated external tank (with its own outlet and inlet), produced a natural water flow. Cold water entered the tank and sank to the bottom, where the water flowed to the coil. Cold water into the coil from the tank, heated and rises, flowing back to the external tank's top, all without pumping or water pressure. (The coil was in the firebox of a wood cooking range.)

    As depicted, the flow direction fights the tendency of heat to rise.

  17. There's a growing market for this kind of stove in the school bus conversion (Skoolie) community. Both heat and hot water in one unit? I would think marketing this to such people would be well received.

  18. Hi Dimtry,
    I'm following this project with great enthusiasm. This will be my retirement home. I'm definitely building one of these kits.
    Wondering about the flue/ chimney location? I note that the deck arches are a fair distance away from the galley and loo, so these chimneys will standing independently, like metal exhaust pipes to a height just under the sail beam(?), correct? At first I imagined them to be fitted into the arches, but that's not really possible, or is it?

    What sort of top cap do they get that would prevent high seas from washing water down the chimney? Or in that situation would one just remove the venting chimney cap and snap on a water tight cap? I would suppose this problem got solved in the 19th century, but just hadn't seen anything about it.
    Thanks for building this dream (boat).
    Cheers, Jake from New Zealand

    1. Hi Jake,
      Yes, the chimneys will be freestanding. They will most likely be removed and stowed away while sailing. The cap can be the standard Dickinson marine flue cap which I have found to work well enough.


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