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. Kits will start at around $50k (USD). The design has been tested in simulation and prototype; full-scale production will begin next year.

Friday, February 8, 2019

Frame Joinery Redux

Although most of the problems with hull structure have already been solved, there remained one problem that stood in the way of completing the design: how to join together the frame. It consists of 4x4 softwood (fir) timbers (3.5x3.5 finished size) combined into a box structure that reinforces the bottom the deck, the bow and the transom and provides support for mast steps. After working out a design that included a dozen different steel brackets that had to be custom-fabricated at considerable expense, I realized that I don’t like it at all: too complicated and too expensive. And so, as usual, I sat back and waited for some new ideas to filter in from the ether.

Eventually this happened. An unrelated project required me to build a rectangular frame by joining together some square cross-section sticks using L-brackets. To avoid the wood at the ends of the sticks splitting as I drove in the screws, I wrapped the ends using several turns of fiberglass packing tape. It worked just fine. The tape took up all the force that would have gone into splitting the sticks along the grain, and the resulting joins were impressively strong.

Transferred to Quidnon’s frame design, this technique will make it possible to assemble the frame using just 3-inch-wide perforated steel strips cut to two or three different lengths and bent to various angles. Some of the brackets will need to be bent to specific angles other than 90º, but this is not a complicated procedure.

The procedure for fabricating the frame now consists of the following steps:

1. Using a chop saw cut 8-foot 4x4 timbers to required lengths.
2. For each timber, shave down the first 6 inches off each end on all four sides using a planer.
3. For each timber, router off the corners on the first 6 inches on all four sides using a router.
4. Roll on a layer of epoxy to the prepared ends, wait until it “tacks up.”
5. Wrap each end in three layers of 6-inch-wide fibergass tape.
6. Saturate the tape with epoxy; let it cure.

Frame assembly then consists of matching up the timbers and the brackets and connecting them together by driving in a lot of self-tapping screws using a cordless drill. There is no need to worry about the wood splitting, and the resulting joints are strengthened by the fact that they are pre-stressed: the wood is compressed between the screws and the fiberglass. In a humid marine environment the timbers will gradually absorb moisture and swell, increasing the pressure on the fiberglass and the screws, holding them in place securely. (The choice of softwood for the timbers is critical: when hardwood swells, it generates enough force to burst fiberglass.) The strength of the joint is determined by the force needed to crush the wood fibers, which is somewhere around 6 times greater than the force it takes to split them along the grain.

There are still several more complicated pieces that will need to be fabricated: engine bracket, mast tabernacles, masthead fittings, tiller and keelboard hardware and bow rollers. These are all key elements of the design and there is no way to simplify them. But the frame joinery is now very well in hand and can be done cheaply using components that can be locally sourced in many places around the world.

Friday, October 12, 2018

A HOUSEboat vs. a houseBOAT

The most important design aspect of a tiny house is the success of its interior layout. The tight quarters may look quaint on paper but in reality turn out to be claustrophobic. The need to stoop and to contort yourself to fit into the small spaces may lead to bumps on the head and cramps. Lack of storage may seem inspirational for those aspiring to minimize their earthly possessions, but inevitably results in clutter. Lack of private spaces may inspire greater intimacy short-term but lead to strained relations in the longer term. And so on.

The set of such problem to solve is even greater when designing a houseboat because of the need to compensate for the almost constant rocking motion in all but the most sheltered marinas and anchorages. Berths (beds) have to be oriented with the head pointing aft: cribs rock side to side and while having your feet bounce up and down is tolerable, having your head do the same generally isn’t. There can’t be any sharp corners, especially where your head or your knees and elbows might end up, and there have to be handholds within easy reach. Shelves and tables have to be fitted with fids to prevent items from rolling off. Dealing with the inevitable condensation is far more important on a boat due to its proximity to water. (Many sailboats will drip cold water on your head as you try to sleep.)

These problems are easily solved by paying a few million dollars for a megayacht, but our goal is to make living aboard an affordable, comfortable, competitive alternative to paying rent. Not only does this tiny house have to float, but it has to be mobile and move both under engine and under sail. The constraints that this imposes on its design are quite formidable. Consequently, only now, after several years of design effort, is it approaching the point where there are no conceptual problems that remain to be solved and construction planning can begin.

Until recently, the design was close but not quite all there. Headroom was adequate for a boat but not for a house—not enough for a tall person to stretch. The cabins were reasonably sized but odd-shaped because of the curvature of the hull. Ventilation was adequate in some spots but missing in others… and so on. The breakthrough came from a very simple realization:

If Quidnon doesn’t make a good tiny house, it won’t matter how good a boat it is.

Previously, we made an effort to appease boat enthusiasts who look for “sweet lines” (curves, that is) and sailing performance (sailing against the wind, that is). Curves are expensive because they add complexity in engineering and construction and result in lots of scrap, while sailing performance to windward is a ridiculous thing to strive for in a houseboat, especially one that has a motor that can be turned on whenever the wind becomes uncooperative.

The effort to indulge and appease the sensibilities of sailing enthusiasts was not successful. They thought that Quidnon was ugly, ungainly and uncompetitive—as a boat. What they thought of it as a house—specifically, as a tiny house—well, they probably didn’t. Sailing enthusiasts either have lots of money to burn or live vicariously through those who do and aren’t interested in tiny houses. And so their opinions didn’t help advance the project.

There is a basic rule that applies aboard boats: if a thing isn’t useful, then it belongs overboard. And so it will be with all of the non-practical considerations that have burdened this project since its inception. Quidnon is a HOUSEboat, not a houseBOAT. Since most of these considerations were purely aesthetic, jettisoning them will not negatively impact performance.

If Quidnon is first and foremost a house, then, like virtually all other houses, it should be rectilinear, with right angles everywhere; basically, a box. There are good reasons why houses are rectilinear: curved floors and slanted walls are nightmarish to live with and more expensive to build. In a rectilinear design all the dimensions can be read off just two drawings—plan and elevation; most of the cuts needed to make parts are at right angles, resulting in less scrap; most of the assembly can be done using a tape measure and a carpenter’s square.

Are there any boats that are rectilinear? Yes, there are, and they are quite ubiquitous. They are called barges. And so Quidnon is now a barge, with just a couple of small concessions to sailing efficiency: the bow is rounded rather than slanted and the aft section of the bottom is curved so that the transom just kisses the waterline. These tweaks improve performance somewhat: the bow generates less resistance while the transom doesn’t drag water behind it. These tweaks don’t add much to the cost or the complexity of the design and don’t produce too much scrap.

Speaking of scrap, minimizing it is key to minimizing the construction cost of the hull: it’s material that you pay for but then simply throw away. Not only that, but you have to actually make the scrap: every piece of wasted material has to be cut out of a piece of stock to make the piece that you are actually going to use. Quidnon minimizes scrap by using whole sheets of standard 4x8-foot (1220x2440mm) plywood as often as possible.

For example, the deck layout is 16x36 feet. Ignoring the openings for the hatches, cockpit and engine well, which do generate some amount of scrap, it is constructed out of two layers of ¾-inch (20mm) plywood screwed and epoxied together (which is then covered with a layer of fiberglass and epoxy and surfaced with aluminum diamond hatch).

Note the tiling pattern: in order for none of the seams to overlap between the two layers, out of the 36 pieces of plywood only five need to be cut in two. This is most easily done on a panel saw. The layer with the cuts will be ¼ of an inch narrower than the layer made up of whole sheets because of the 1/8 kerf of the cuts. But ¼ of an inch distributed across 7 gaps is less than 1mm per gap and is negligible.

Similarly for the sides and the bottom. Each side is made of 18 sheets of 4x8, only one of which has to be cut in half lengthwise. Some amount of scrap then needs to be cut away to make the profile of the bottom and the bow. But then the construction of the bottom hardly generates any scrap at all. The overall goal is to have less than 10% of the plywood end up as scrap.

In addition to minimizing scrap, the barge hull shape has made it possible to dramatically improve the ergonomics of the cabin layout. Headroom is 6½ feet (2m) just about everywhere. There are four double-berths (beds) that are 6 ½ by 4 feet (2m by 120 cm). Most importantly, there is now room for a very comfortably sized stateroom (living room) in the bow.

Let’s take a tour of Quidnon’s redesigned cabin, starting at the bow and working our way toward the transom.

When I first started designing Quidnon, the very first seemingly insoluble problem I came across was where to put the couch, the coffee table and the TV. Few reasonable people would agree to live in a house that’s missing a living room, a den or similar. Having looked at a lot of boat designs, both sail and power, none of the reasonably small, reasonably priced ones had anything that resembled the traditional living room found in most homes. A good living room has a couch, one or two armchairs, a place for a TV set, a few end tables and a coffee table to tie it all together. The best ones have lots of natural light and a great view.

So, how can Quidnon provide all of that? Switching to a barge hull opened up what was before an awkward, cramped wedge-shaped space in the bow (that is found on most boats) into a spacious 160 sq. ft. (15 m2) rectangle. There is room for a wrap-around couch, two end tables, a huge 3 by 6 foot coffee table and enough bulkhead space to mount two 50-inch screens.

There is also quite a bit of storage space: 10 cu. ft. inside each of the end tables and 20 more under each of the port and starboard settees (couches; the seats tilt up) for a total of 60 cu. ft. (1.7 m3).

Above the settees there are two rows of shelves with 34 linear feet of shelf space, enough to hold a 500-volume library.

Above the shelves is a row of deadlights (which are portlights that do not open). The commercially available deadlights and portlights start at around $200 each. For Quidnon’s 44 deadlights, that would come to at least $8800. To avoid this expense, Quidnon’s deadlights are just 1 ft. diameter holes milled through the hull with a layer of 1/4-inch polycarbonate plastic caulked and fastened over them on the outside. Since the holes weaken the structure of the sides by around 50%, this is compensated for by doubling the hull thickness by adding two strips of plywood, 16 inches wide, over the holes. The materials cost for the additional plywood and the polycarbonate is around $1200.

Lastly, the two red boxes in the two corners of the bow are air vents that are connected to a deck arch above. The vents are louvered and can be adjusted for both intake and exhaust of outside air.

Moving aft from the stateroom is the salon, which can be partitioned from the stateroom by a folding divider.

The salon contains two facing settees (couches) with a drop-leaf table between them. On both sides of each settee is an end table. The seats of the settees tilt up to provide access to the storage space beneath them, providing, together with the end tables, 40 cu. ft. of storage space.

In the center of the table, between the two drop leafs, is a vertical slot that is ideal for securely holding laptops and tablets, cell phones, keys, wallets and other small but important items.

Above the table is a large translucent hatch (skylight, shown in light green) that provides a lot of light. It is designed to prevent ingress of all forms of water (rainwater, sea spray, condensation) and can be angled up slightly for ventilation. It can be removed completely for loading and unloading, making it unnecessary to haul heavy loads up and down the companionway ladder. A deck arch, mounted directly above it, provides an attachment point for a hoist.

On both sides of the salon are pilot berths. They are accessed through hatches that are above the backs of the settees and are separated from the salon by double longitudinal bulkheads that form the walls of the keelboard trunks. The pilot berths’ hatch doors are thick and filled with foam, and together with the double bulkheads provide excellent sound insulation and privacy.

The pilot berths (beds) are 6.5 by 4 feet—large enough to comfortably sleep two adults.

At the foot of each berth is a sea chest that provides 20 cu. ft. of storage space for clothing, children’s toys (the pilot berths are perfect for children and as nurseries) and other possessions.

The pilot berths are supplied with fresh air through air vents connected to a deck arch above. With the pilot berth hatches open, they can also provide fresh air to the salon.

Below the pilot berths are the water tanks. At 135 cu. ft. each, the two tanks provide 8 tonnes of salt water ballast. Fresh water is stored within these tanks inside floating bladders—up to 2000 gallons of it. As fresh water is used up, it is replaced by water from the outside using a pressure-activated pump. The use of water ballast adds a lot of versatility. It is necessary when moving under sail and/or through large seas; it is helpful when docked or at anchor, to reduce motion; it isn’t necessary or helpful when motoring on inland waterways and being able to dump it when hauling out or when recovering from a hard grounding is a positive benefit. It also saves lots of money (the equivalent weight in lead would cost over $16,000) and provides the added benefit of being able to store 2000 gallons of fresh water.

Moving further aft, there is the galley (kitchen) to starboard (right), the heads (bathroom) to port and a companionway (vestibule) in the center. Only the galley is shown in the elevation drawing. The galley cabinets provide 50 cu. ft. of pantry space.

The heads offers the usual amenities, including a full-size shower stall that can be fitted with a bathtub. All sorts of options are possible for both the galley and the heads, including composting toilets, flex-fuel stoves and the likes. If the stove in the heads is eliminated (not everyone plans to overwinter aboard in the Arctic or needs an on-board sauna) then there is enough room for a vertically stacked washer-dryer unit.

The companionway is an open area that links together the heads, the galley, two aft cabins, the salon and the cockpit via the companionway ladder. At the bottom of the companionway ladder is a foot locker while hooks along the sides of the companionway are for hanging outdoor clothing.

Aft of the companionway are the two aft cabins. Each has a table with a seat, a row of shelves and a double berth. The table can be used as a chart table and the shelves packed with navigation equipment, but it can also be used for doing any other type of sit-down work. Space under the berth provides 40 cu. ft. of storage space.

The aft cabins and the heads can be closed off using sliding doors (shown in magenta). These doors are counterweighted so that they don’t spontaneously slide back and forth due to the motion of the boat but stay in place.

Between the two aft cabins is the utility chase that includes the cockpit, the anchor chain and line locker beneath it, the engine well and the gasoline tank and propane locker further aft. The engine well is heavily insulated to dampen the engine noise when motoring. Since the engine is a gasoline outboard rather than a diesel, it produces a high-pitched whine rather than a heavy throb, and is easier to suppress using a few layers of foam.

This, then, is the tiny house that will also function as a houseboat and a sailboat. Some things about it are still distinctly odd for a house; the shape of the windows for one, the fact that you enter it via the roof (deck) for another. But this can’t be helped; if you could enter it at ground level, then so could water, and house windows don’t work at all when submerged.

Now that Quidnon is barge-shaped with no funny angles the joinery has become dead simple. It involves plywood panels screwed and glued to softwood strips. And then the entire hull gets fiberglassed on the outside, making it relatively indestructible.

Quidnon’s conceptual design is now complete. What lies ahead is producing the detailed mechanical drawings, the bill of materials, a parts list and a set of assembly instructions. Much to the dismay of boat hobbyists and enthusiasts, the sailors among them especially, it is manifestly and resolutely a HOUSEboat, not a houseBOAT. It will get built, and people will live aboard it. Once in a while this shoebox of a boat will erect its masts, drop in a motor, hoist the sails, promenade around the harbor in stately splendor and eventually disappear over the horizon, to the slackjawed amazement of tourists and bystanders.

Friday, October 5, 2018

Coppered Bottom is a No-Brainer

The last post on the Quidnon blog attracted some attention from various places around the net. One in particular—the forum Sailing Anarchy—attracted over 400 visitors. I followed the link and tried participating in the discussion.

The sailing anarchists just couldn’t wrap their heads around the concept of a houseboat as a lifehack that lets one avoid getting wiped out by exorbitant real estate prices and rents. Well, I’ve said this many times before, but I’ll say it again, briefly: in the US, housing is a racket, on par with other rackets, such as health care, higher education, national defense and quite a few others. The very lightly regulated recreational vessel space offers a wonderful opportunity to escape the landlubber debt trap.

The sailing anarchists also couldn’t accept the idea that it is better to build a boat from scratch, at considerable expense, than to buy an existing, used boat, many of which can be had for very little money. The problem there is that none of the existing boat designs fit the bill. Sailboats are either big and unaffordable or small and too cramped. Powerboats with accommodations for a family are also too expensive, both to own and to move from place to place because of exorbitant fuel bills. Houseboats are generally dock-bound and not seaworthy in any sense.

Some anarchists thought that the Junk rig wouldn’t work well. Little do they know that the Junk rig is one of the oldest and most successful designs in the world that has stood the test of time, providing low-cost propulsion and ease of handling for more centuries than any other. Some thought that the boxy hull shape was unstylish, ugly and simply wrong, unaware of the fact that sailing barges, scows, cargo lighters, dhows, bateaux and junks of similar lines had been the staple of coastwise navigation around the world throughout the age of sail.

I presented my list of requirements which Quidnon must fulfill, but which no other boat does, to no avail. Apparently, these anarchists are rather closed-minded. Not a single comment they made was on target. But one valid question did come out of the discussion: Why cover the bottom with copper sheet when bottom paints are available. Since this is an easy question for me to answer, and since the answer is instructive and demonstrates the type of thinking that informs the whole design, I will answer it.

Quidnon’s bottom is 16 by 36 feet, or 576 sq. ft. The bow, transom and sides below the design waterline add an additional 208 sq. ft for a total of 784 sq. ft. Roofing copper comes in 4x8-foot sheets, or 32 sq. ft. Dividing one into the other gives us 25 sheets. 16-gauge (1/16-inch) copper sheet is currently priced at $91.29 per, for a total of $2,282.25.

This may seem like a considerable expense, but now let’s consider the cost of bottom paint. After much experimentation I settled on Interlux Micron CSC Ultra as the longest-lasting paint. It costs $209.99/gallon and its datasheet claims that a gallon of it covers 439.7 sq. ft in a single coat. The manufacturer recommends 3 coats and a minimum of 2. This gives us 784 sq. ft times 3 coats divided by 439.7 sq.ft/gallon, giving us 5.3 gallons or $1,123.

Note that the paint only works for about a year; after that, the bottom starts growing slime, then sea grass, then barnacles and mussels. If you don’t plan on going anywhere, then you can just let your boat turn into a floating island festooned with seafood. But the need to move may arise suddenly: the marina may close because of an approaching hurricane and kick everyone out; your job situation may require you to move your floating home to a new location; a shortage of money may require you to give up the slip at the marina and take up life at a mooring or at anchor. With a neglected, painted bottom the prerequisite to moving is an expensive and lengthy (3 days at least) haul-out which includes hiring a Travelift and someone to pressure-wash and paint your bottom (unless you yourself enjoy spending your days with a roller, wearing a bunny suit and a respirator, and being exposed to toxic fumes anyway). Haul-out and bottom painting costs vary, but you generally end up spending upwards of a thousand dollars, and if you want your boat to be able to move effectively, you need to do this every year.

And so by going with bottom paint instead of copper sheet you will save $2,282 minus $1,123 in construction costs, or $1,159. But every year thereafter you will spend a minimum of $1,123 + $1,000 or $2,123 in maintenance costs. Over the 30-year expected lifetime of the boat, this will amount to as much as $60,000. Compare that to copper sheet: yes, you will pay extra up front, but thereafter all you will need to do is a semiannual cleaning: find a sheltered, shallow spot that dries out at low tide, anchor, wait for the tide to go out, and then take a scraper on a long handle, a roofing spade or a similar hand tool and scrub all of the copper you can reach. The seafood you can’t reach will be crushed and fall off by itself. If that’s still too much work, then you can hire a diver to scrub the bottom for you while the boat sits at the dock. This service generally costs only a few hundred dollars and can often be done on short notice—when you find out it’s time to move.

Attaching the copper to the bottom is slightly technical but not particularly difficult. The bottom is made up of 3 layers of 1/2-inch plywood screwed and epoxied together. Fiberglass matt is then nailed to the plywood using bronze annular nails and saturated with epoxy. The matt is then covered with 3 layers of fiberglass cloth, leaving an epoxy-coated surface, tipped off with a soft brush to make it perfectly smooth. The task of attaching the copper sheet is then as follows:

1. Thoroughly abrade the epoxy on the bottom with 100 to 200-grit sandpaper using a rotary sander.
2. Clean off sanding residue using denatured alcohol. Be sure not to leave any fingerprints.
3. Thoroughly abrade one side of a copper sheet with 300 to 600-grit sandpaper using a rotary sander.
4. Degrease using trichlorethylene.
5. Rinse the copper sheet in one of two solutions for 1-2 minutes. Option 1: 6 parts copper chloride, 30 parts 70% nitric acid; 200 parts water. Option 2: 25% aqueous solution of ammonium persulfate.
6. Rinse with distilled water; let dry.
7. Coat the bottom evenly with epoxy and apply the copper sheet prepared side down. Use cotton gloves when handling the copper sheet to avoid contaminating the contact surface.
8. Cover the copper with polyethylene sheet, then weigh it down with sandbags until the epoxy has set.

Why don’t other boatbuilders use copper cladding for the bottom? Well, it used to be a popular option during the age of sail. Ships were periodically run aground (careened) to have their bottoms scrubbed. But ships now use powerful bottom paints (illegal for use on smaller recreational boats) while for smaller boats copper is simply not an option. Look at the bottom of just about any commercially produced boat. It is made up of compound curves, and it is an expensive proposition to make copper sheets take up compound curves. Add to that the fact that most commercially produced recreational boats are made of fiberglass and vinyl rather than epoxy, and these don’t provide a good substrate for attaching copper sheet. Quidnon’s bottom is curved (slightly) in one direction only—fore and aft—and can be tiled with sheets of copper: 4 sheets across and 5 sheets lengthwise, for a total of 20 sheets with almost no scrap.

There is nothing to stop anyone building a Quidnon from deciding to use traditional bottom paint instead of the even more traditional copper sheet, but the decision to use copper appears to be a no-brainer: lower costs, no need for haul-outs and time spent on the hard in a boatyard and generally more flexibility.

Monday, September 17, 2018

Quidnon 2.0

This boat design project started out by setting out some very ambitious requirements:

• A houseboat that makes a comfortable tiny house big enough for a family
• A competent, seaworthy sailboat, with masts that can be put up and taken down by a single-hander with the boat in the water
• A motor boat with an outboard motor for an engine that can be installed and removed easily, positioned in an engine well to prevent cavitation, collision damage and other problems with transom-mounted outboards
• Never needs a haulout: copper-surfaced bottom resists marine growth; settles upright and can be dried out and scrubbed at low tide
• Can be beached and relaunched by rolling over logs using anchor winch
• Can be assembled quickly from a kit on a beach or a riverbank by moderately skilled people
• Uses materials that are readily available almost everywhere: plywood, softwood lumber, bolts and screws, fiberglass and epoxy, galvanized mild steel, polypropylene three-strand rope
• Designed for all climates and seasons, from frigid to torrid
• Can be constructed and maintained at minimal expense

Over the past four years since I launched this project several people have made significant contributions to it: modeling, prototyping, contributing ideas and criticisms, helping spread word of it. Taking our sweet time with it has been very helpful in preventing us from building the wrong boat.

But what would be the right boat? How will we know when we have the right design? Well, one very basic indicator would be an empty list of unsolved problems—problems not in the sense of having every last detail worked out on paper (that’s largely a matter of grinding out mechanical drawings) but in the sense of not being sure what to do. And until very recently the list of unsolved problems contained the following big ones:

• No good, useful interior layout for the U-berth (the front section, normally called the V-berth, but Quidnon’s bow is semicircular, making a U). We went round and round on it, but the space was just too awkward.

• No reasonable procedure for installing and removing the keelboards or the rudder with the boat in the water.

• Complex joinery that required pieces of lumber to be milled to a variety of bevels, then steam-bent, adding expense and making the kit difficult to pack flat.

• The angled twin rudders, and the rudder linkage that went with them, gradually grew in complexity to include Ackermann geometry, a system of levers for amplifying the tiller angle and various other details, making it quite baroque.

• There was no straightforward way to construct the chain runners so that they would be neither too fragile nor too heavy and expensive.

• Rolling the hull over logs is made difficult because the bottom is curved throughout, causing the logs to squirm out from under it.

There were a couple of other, relatively minor problems as well. I will mention them later on.

And then something happened that broke this entire logjam: I consulted with a marine architect who raised certain criticisms of the design. They made perfect sense, and forced a rethink that made all of these problems go away.

• The hull doesn’t heel enough to make chine runners effective. They only work well at a considerable angle of heel, and with a hull as wide as Quidnon’s the heeling angle is insufficient to make them scoop up enough water to stop the sideways slide. Solution: get rid of them altogether.

• The hull doesn’t heel enough to make it necessary, or at all useful, to angle out the keelboards or the rudder blades. Solution: make them all vertical. It then begins to make sense to make the keelboard trunks into full double longitudinal bulkheads with a slot between them, leaving them open both at the bottom and at the deck. Keelboards can then be loaded into the trunks from the deck. An added bonus is that this creates a double baffle between the salon and each of the pilot berths, providing sound insulation. Another added bonus is that there are now two large deck drains, to quickly get rid of any seas that climb aboard.

• There is no reason to introduce the cost and complexity of twin rudders. Solution: have just one rudder, mount the rudder post on gudgeons and pintles along the aft wall of the engine well with the rudder blade nestled in a recess under the transom (which is already included in the design, to let through the stream from the prop). Instead of the baroque linkage, we can then have a simple tiller connected to the top of it. When at anchor or at the dock, the rudder can be pulled out to reduce noise and wear.

• There is no reason to curve the sides or to angle them out. It doesn’t improve sailing or motoring performance at all, but it complicates the joinery. It is better to simplify the construction, minimize the cost and maximize useful interior space by making them flat and vertical. This gets rid of most of the complex joinery and the need to steam-bend pieces.

• If the sides are flat, there is no reason to curve the bottom throughout. It has to have a curve at the bow, to help it move smoothly over the water, and it has to curve up gently toward the transom, to avoid dragging water behind it and to keep its center of buoyancy where the ballast is. Giving it a generous flat section in the middle makes it possible to roll it over logs while further simplifying the joinery.

• The fancy bow, where the sides sweep together to meet the bottom at a flat point, will not help performance. On the other hand, it is what makes the space in the bow so difficult to make any reasonable use of. The solution is to make a simple barge hull: at the bow, the bottom curves up to the deck with constant curvature while the sides are perfectly flat. This makes it possible to use the space as a comfortable livingroom of 114 sq. ft. (10 m^2).

What will the result look like? Well, my new motto is “Start your morning with a 3D model and get it over with.” Here is the 3D model, constructed out of highest-quality cardboard and scotch tape.

Yes, Quidnon looks like a barge. That’s because it is a barge. Efforts to make it look like something else—by slanting and curving the sides and giving it a fancy bow added complexity and expense while taking away useful internal space. Also, these little nods in the general direction of yacht design did nothing to appease people who like fancy yachts with curvy lines—there is no pleasing some people!

These major simplifications make it possible to produce the detailed plans over the course of the next few months. This is important, because the money with which to build the first Quidnon should be in hand over the course of the next year, allowing us to move on to the next phase: building and testing it.

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 -20ºC 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.

Tuesday, February 27, 2018

Marine Russian Stove, Take 2

[Update: I added a schematic of the hot water plumbing system and improved the description of how it will operate.]

Thanks to all the feedback I received for the previous iteration of the design, it is much improved.

The basic goals of this design are as follows:

• The stove has to be cheap and easy to fabricate as a kit out of sheet metal stock using a plasma cutter and a brake.

• It should be easy to assemble the kit using a few hand tools: wrenches, screwdrivers and a pop riveter.

• It should be able to burn either wood or charcoal.

• It should also make it possible to fit a propane burner as an option. (Some marinas do not allow solid fuel stoves.)

• It should provide heat to a cooktop, a water heater and an air heater. Each of these may or may not be in use at any given time.

• It should produce negligible amounts of radiant heat (except from the cooktop, and only when it is in use)

A lot of people commented in favor of heating a thermal mass, and this is indeed a good idea. Thermal mass heaters, such as the traditional Russian Stove, use masonry to hold heat. But masonry doesn’t have a place aboard a boat, and hiding a few bricks inside a sheet metal stove won’t make much of a difference. However, there is one substance that is better than masonry at storing heat, and it’s free. It’s seawater. It takes 4.18 J/gK to heat seawater, while soapstone—the preferred material for solid mass storage—is only 0.98 J/gK, so its more than four times worse at holding heat.

Quidnon holds 5 tons of water ballast, and the best way to store heat aboard a Quidnon is to heat the ballast water to some reasonable temperature, such as 15ºC (60ºF). Running salt water through the water heater will cause it to crust up with salt deposits that can only be removed mechanically, using a grinder. It is much better to reinject heated fresh water from hot water tanks into the fresh water bladders floating inside the ballast tanks. This would also heat the surrounding ballast water, producing the same effect.

But this was part of the plan all along. The following realizations, however, are new, and demonstrate the power of the design process we’ve been following on this blog, where experienced people contribute many excellent ideas.

The first very important realization, thanks to Rhisiart, is that the stovetop needs to be directly above the firebox in order to produce sufficient temperatures for applications such as stir-frying and generating steam for the sauna (via sauna stones). But the stovetop doesn’t need to always be hot. When the stove is being used to heat the interior of the boat (via hot air) and/or to heat water, it should be possible to close off the stovetop using a sliding baffle.

The second very important detail, contributed by Jef, is that it is very important to be able to completely seal off the firebox from the interior airspace and to feed the fire by taking in outside air. I already knew how important this is: lighting a charcoal stove on board on a stormy night would sometimes send ash and lighter fluid fumes flying into the cabin. The trick was to catch lulls to light the flame, because once the draft was established wind gusts no longer mattered much.

This has prompted me to follow Jef’s advice and to add two air injectors. The bottom air injector is used for stoking the flame and can be driven by a small fan. Once the fire is burning, the top injector is used to produce combustion of the flammable gases emitted by the wood at just the right spot. The flow rate for the injector can be turned down, to keep a couple of hardwood logs burning all night, or turned up, to rapidly heat the stovetop and/or a lot of water.

Other parameters of the design were relatively easy to derive. A 3-inch flue is reasonable for a boat-based stove (I’ve used it successfully before). The cross-section of the flue has to remain the same both inside and above the stove. There is enough space available on Quidnon for a 16-inch-wide stove (plus a couple of inches all around for rock wool insulation and an exterior jacket made of either aluminum or stainless steel sheets pop-riveted together). Thus, the width (w) of the flue box inside the stove is 16 inches, and its depth works out to

πr2/w = 3.1415 * (3 / 2)2 / 16 = 0.44 = 7/16 inches

The most common size of firewood is 16 inches long, so the firebox is 17 inches deep. It is reasonable to keep the profile of the firebox reasonably square, so it is 16 inches wide by 16 inches tall. The ash box at the bottom and the stovetop compartment at the top, above a baffle, bring the total height to around 30-32 inches.

The reason the section below the stovetop is taller than at first appears necessary is because of the threshold. Thresholds are commonly used inside stoves to keep in the hot gases, raising the combustion temperature and making for a more efficient burn. There are two thresholds: one in the firebox, and one below the stovetop. The front opening of the stove (which is fitted with a door that seats tightly against a gasket) is sized so that the top of the opening is just below the bottom of the threshold, to keep combustion gases from escaping into the cabin while loading firewood. The ash box is similarly sealed from the inside air.

There are two heat exchangers: air and water.

The simplest and cheapest heat exchanger design is one with hot flue gases on one side of a metal plate and the medium to be heated on the other. For the air heat exchanger, just as with the flue, it is important to maintain the same cross-section both outside and inside the stove, and a 3-inch duct is reasonable for piping hot air under the cabin sole and distributing it throughout the boat. This translates to the depth of the air heat exchanger also being 7/16 inches. It may at first seem strange that the cold air is pumped in at the top, since hot air rises, but this makes no difference since it then has to be forced under the cabin sole anyway.

For the water heat exchanger, the flow is much slower because of the very high heat capacitance of water, and matching the cross-section of the input and output pipes to the cross-section of the heat exchanger is unnecessary. Above the stovetop, the flue forms a square box, insulated on the front. It shares its back wall with the water heat exchanger box, which has a couple of nipples welded to it for letting water in and out.

It is a given that the water heater will generate some amount of steam, and this steam has to be released. It is also a given that quite a lot of the time the water heater will not be used, and the stove’s sole job will be to heat air. This will make it necessary to vent the steam and to let the heat exchanger stand empty.

For this, I am thinking of doing the following.

A demand pump set to 16 psi injects cold water from the fresh water tanks directly into the hot water tank until the air release valve located near the top of the tank starts spitting water and is manually closed. The air release valve is connected to a nipple located a couple of inches from the top of the hot water tank, leaving an air pocket at the top that allows it to operate as an expansion tank, absorbing excess pressure periodically generated by steam. The demand pump keeps the tank permanently near full and pressurized as water is drawn from it. So far, this is just a pressurized cold water system with a reserve tank.

When the stove temperature sensor reads above 80ºC, a second pump starts injecting water from the hot water tank into the top of the heat exchanger. This is not a demand pump but a simple circulator pump, and it doesn’t particularly care what pressure it’s generating (up to a point). The heated water drains out of the bottom of the heat exchanger and back into the hot water tank through a check valve. It keeps running until a temperature sensor in the hot water tank reads above 80ºC.

It is at that point—when the circulator pump stops running—that an interesting series of events has to unfold, because the remaining water trapped inside the heat exchanger starts to boil and generate steam. Steam pressure forces most of the water remaining in the heat exchanger down into the hot water tank. As steam pressure in the heat exchanger continues to increase, the pressure relief valve opens and vents the steam.

As steam is being vented, pressure in the heat exchanger falls below 16 psi but the check valve keeps water from being forced back up into the heat exchanger. The heat exchanger then stands mostly empty (if the check valve leaks a bit, the pressure relief valve will periodically produce puffs of steam) until the hot water tank cools down below 80ºC, and if at that point the stove is still above 80ºC the circulator pump starts squirting water into the heat exchanger again. After some amount of hissing, during which the heat exchanger generates steam, the hissing stops and water starts being heated again.

Tuesday, February 13, 2018

Marine Russian Stove

During the decade or so we have spent living aboard, we went through a succession of methods to keep the cabin warm during the cold months. On our first journey south, we cast off from Boston in mid-October, the day before the marina would have kicked us out because we hadn’t signed a contract for winter dockage. We progressed south rather more slowly than we had expected, and made it as far as Charleston in early December. There we decided to overwinter, and proceeded further south three months later. When we first set off, all we had on board was an electric space heater, plus a propane heater powered by 1 lb. camp stove canisters. We went through a large pile of these. The electric space heater only worked when we were tied up at the dock and plugged in to shore power. While under way, we tried to keep warm by burning propane. But propane generates a lot of moisture as it burns, causing the entire cabin—the clothing, the bedding, everything—to become dank, robbing the body of heat, while the moisture in the air condensed on the underside of the cabin top, causing it to literally rain inside the cabin. (There are few things more disagreeable than an intermittent cold drip on your head as you are trying to sleep.) When we got to Baltimore, we tied up at a marina to which I had previously arranged to have shipped a propane-fired Cozy Cabin Heater. It was designed to be plumbed to a 20 lb. propane tank, and included a flue, thus solving the moisture problem. I installed it using the materials on hand and life got significantly better. Once in Charleston, where we overwintered, we used this heater along with the electric space heater, and the cabin stayed comfortable.

Eventually we got back to Boston, by which point the Cozy Cabin Heater died, as had the company that made it, and hunting down replacement parts for it turned out to be a nightmare. This is not at all unusual: most of the equipment manufactured for the recreational marine market is shoddy, overpriced and falls apart rather quickly. At that point, as part of a thorough refit, I replaced it with a Tiny Tot charcoal stove, made by a tiny company somewhere in Michigan. The heat it delivered was intense and very dry, and kept the cabin toasty all by itself on even the coldest nights with no condensation problems. But we had to get up every 2-3 hours to add 5-6 charcoal briquettes. Solid fuel stoves were forbidden at the marina where we stayed, but nobody noticed. Also as part of that refit I insulated the entire cabin with two layers of radiant barrier, ½ inches of Pink Panther foam insulation, another layer of radiant barrier and a layer of fancy 1/16-inch varnished cherry plywood with oak trim. This made a huge difference: there were no more condensation problems and the cabin felt warmer than one would have guessed by looking at the thermometer. The one remaining problem was the cabin sole: there was no way to insulate the bilge and it was still cold. In spite of putting down rugs everywhere possible, it was difficult to keep our feet warm.

We were about to set off sailing again when we became pregnant and had to “upgrade” to a larger boat. The reason “upgrade” is in quotes is because we sold a very good boat—Hogfish, the eminently serviceable, versatile and fun 32-foot sharpie custom-built by Chris Morejohn—and bought an unwieldy, boring maintenance nightmare that is the typical commercially built yacht—a 36.5-foot Pearson. Its only real selling point is that Pearson made a mistake and made the fiberglass of the hull ridiculously thick, thus making it fairly indestructible. Over the five years that I owned that Pearson I came to genuinely detest it. Rest assured that I will never buy another commercially built production boat again, having learned firsthand all the different ways in which they are crap. As far as I am concerned, it’s either going to be a Quidnon—or a nice homestead. But if all goes as we expect, I’ll have one of each.

The Pearson came with a very strange piece of equipment: a Newport evaporative diesel heater. It used a little electric pump to squirt diesel oil into a bowl, and it was your job to get it burning. This involved tossing in some tissue paper soaked in diesel, lighting it on fire, and using a little electric fan to vent the fumes and fan the flames until the bowl of oil heated up enough to start evaporating and burning on its own. When everything was working as it should, it produced a pretty-looking warm glow, much like a fireplace. The rest of the time it produced prodigious amounts of soot and made the cabin stink of diesel oil. And the once in a while—invariably on a cold and stormy night—it would blow out, and coat the walls of the cabin, and everything inside it, with a fine film of smelly, oily soot. We used that heater for one winter, then gave up on it and let it sit, unloved and unused. As far as the rest of the boat, we did get some use out of it. I moved it south one summer, single-handing all the way down the coast, then had my family fly down, and there it stayed, at the dock, until we sold it. I didn’t enjoy sailing it; it sailed like a pig, with a strange corkscrew motion and a jarring “stomping on the breaks” effect at every other wave as the Pearson buried its fat snout in it. Well, that’s what you get with a hull that’s shaped like an endive. Its best feature by far was the heads: it had a full-size shower stall. Its second-best feature was the galley—once I tore out and rebuilt half the cabinetry.

Another problem with an endive-shaped hull (and most production cruising sailboats are, unfortunately, shaped like that) is that is almost impossible to insulate. On Hogfish, the sides were made of flat plywood sheets, curved in a single direction, and this was easy to insulate by adding flat slabs of foam. This is also going to be the case with Quidnon. Also, on Hogfish the sides were accessible, while the Pearson the cabin was a mess of fiberglass forms, one wedged into another before the deck got screwed on. (Yes, the deck was screwed on, not bolted on, using sheet metal screws bedded in epoxy; the wonders of commercial boatbuilding never cease to amaze!) Clearly, the designer had spent zero minutes thinking about how this hull could ever be insulated. Thus, the Pearson stayed uninsulated, and the cabin felt cold no matter how many electric space heaters we had going. We used a thick rug in the salon and electric blankets under all the mattresses, and that helped. We also taped bubble wrap under all of the hatches and insulated the companionway hatch as best we could.

As an aside, the economics of unique, versatile, custom-built boats like Hogfish, and like Quidnon is going to be, and sloppy production boats like the Pearson are very different. When I put up Hogfish for sale it sold almost immediately, and I doubled my money on it. If I hadn’t accepted the first offer (which I did because the buyer matched my asking price) there would certainly have been a bidding war. The Pearson stayed on the market for six months and eventually sold for a miserably small amount of money, because there is a glut of very similar boats sitting on the market forever, unused and unloved. The closing date for the sale fell on my birthday, which I took to be a sign that Neptune had taken pity on me. This contrast hints at what the situation will probably be like with Quidnons, once there is some number of Quidnons floating about. There are likely to be bidding wars for any of them that come on the market, be they bare hulls or be they finished boats with all of the equipment and amenities installed.

Getting back to the question of how to heat the cabin, our plans for Quidnon is to make it very comfortable and cheap to heat. Last week, Chris Raine asked a profound question: “Will this houseboat also have a Русская печь?” This question, I thought, requires an equally profound response, so here it is. What follows is an excerpt from my book Shrinking the Technosphere.

The design of the Russian stove is several centuries old and seems to have emerged soon after the spread of firebrick, which is a formulation high in silica that is less susceptible to spalling when heated repeatedly. It is a massive masonry structure with its own foundation. At its center is a vault with an arched ceiling and a flat floor, often high enough for someone to squat inside. Fire is set inside the vault, far inside the stove. At the front of the stove is a flue, which includes a dogleg with a gate that is used for hanging meat and sh for smoking. Right back of the flue is a threshold that protrudes down from the top of the vault, holding hot combustion gases inside the innermost part of the vault, resulting in better heat transfer. The top of the vault is filled with solid fill and covered over with a layer of brick, forming a platform, and a straw-filled mattress, which is often big enough to serve as a bed for an entire family of five. Between October and May, when the stove is red twice a day, the temperature of the platform stays at a constant, comfortable 25–27ºC (76–80ºF). During the hot part of the summer, when the stove is not red because cooking is done at an outdoor hearth, the stove provides a cool place to sleep.

The outer wall of the stove has several niches. They improve heat conduction from the stove to the air in the room and are also used to dry clothes, herbs, mushrooms and berries, to keep food warm and to provide a place for the samovar, which boils water for tea. The firebox of the samovar, typically stoked using pine cones, exhausts into the flue of the stove. Under the stove is a space that is used to store firewood and can be a warm place for animals to sleep. The stove can also be used as a sauna—by sitting cross-legged inside the vault when it is relatively cool.

The Russian stove includes an entire dedicated set of utensils that are specific to it, each perfected over the centuries to have the largest possible set of functions. Food is cooked in clay pots and in cast iron skillets that lack a handle. The pots are placed inside the stove using stove forks, which come in three sizes and grab pots by the neck, while the bread and the skillets are moved about using a flat-bladed wooden spade, similar to the paddles used to handle pizza.

For the sake of comparison, let’s consider what you’d have to shop for if you didn’t happen to have a Russian stove. To heat the house, you’d need to buy a furnace and either install an oil tank or hook the house up to a gas main. Then you’d need to construct a way to distribute the heat, through either forced air or baseboard heating, and this involves installing lots of either ducts or pipes. You could also install a modern, energy-efficient wood stove, but then the bedrooms would be cold, so you’d probably run out and buy some electric space heaters and, to keep the beds warm, some electric blankets. To cook food, you’d need to buy a cooking stove with an oven, either gas or electric, a toaster and a microwave oven. You’d need a separate smoker for smoking fish and meat, plus some drying racks for drying things. Or you could just get rid of all this expensive, short-lived junk and render yourself naturelike by building yourself a Russian stove and using it in place of all of the above.

From Shrinking the Technosphere, p. 139-40

So, how does one adapt the Russian Stove concept to a boat? Obviously, placing a massive masonry structure on board is out of the question. But after giving the question some thought I found ways to provide for most of the rest of its uses, including all of the following, using a relatively lightweight structure made of sheet metal:

• Keeping the cabin warm and providing warm, dry places to sleep and sit
• Heating water for showering, bathing and washing and to keep water ballast tanks from freezing
• Cooking
• Making steam for sauna
• Generating electricity
• Drying things

There will be two identical stoves—one in the galley, one in the heads/sauna—that will burn wood, charcoal or propane (since some doing like having to stoke a stove, and some marinas forbid the use of solid fuel). To burn propane, the ash box is replaced with a propane burner; the firebox can then be repurposed as an oven and used for baking or broiling. But when cruising or overwintering along wooded shores propane may be hard to come by while firewood is likely to be plentiful and either cheap or free for the taking, and so the option to burn wood is very useful.

Above the firebox is a stack of three heat exchanger compartments. Flue gas from the firebox can be sent through any of them using diverter valves. Right above the firebox is the water heat exchanger; next is the air heat exchanger; and at the top is the hot plate used as a cooking surface. The flue gas is then discharged into an 10-foot smokestack that penetrates the deck and rises above it, to produce plenty of draft. The sides and the back of the stove are double-walled, with a layer of rock wool between the walls for insulation.

The back wall, which is in contact with the hot flue gas, is especially well insulated, with a layer of aluminum flashing sandwiched between two layers of rock wool to provide a radiant barrier. A patch of the back wall is left uninsulated; there, a thermoelectric generator module is attached directly to the steel plate that is contact with the hot flue gas. The cold side of the thermoelectric generator is cooled by circulating ballast water through a water jacket. The two thermoelectric generators will provide a total of 100W of DC current—50W on each stove—and also keep the ballast tanks from freezing.
In the heads the hot plate surface has a pile of sauna stones attached to it using a stainless steel mesh. Having a sauna on a smallish sailboat may seem like an extravagance, but the Finns, the Russians and many others would disagree. I am sure that anyone overwintering on a Quidnon would value having a sauna on board.

Since most people prefer to cook with propane rather than fire up the stove for that purpose, in the galley the hot plate will usually have a propane cooktop placed over it. Above it is an exhaust hood vented to the outside; in the relatively small space of the cabin, it is essential that cooking smells not be allowed to permeate the cabin.

Space heating is via warm air. A circulator fan takes a mixture of outside and inside air and pushes it through the air heat exchanger. The output is injected into a network of ducts and plenums under the cabin sole which distributes the heat evenly throughout the cabin.

The plenums can be adjusted for optimum heat distribution and to suit the preferences of the occupants of each cabin and berth. Some of the warm air is sent under all of the berths, to keep the bedding warm and dry. In addition, warm air can be sent into the cockpit lazarettes and the cockpit well, to keep the cockpit warm and to provide warm places to sit while sailing. To keep the heat in, the cockpit can be enclosed using sliding window panels along the sides and a transparent vinyl curtain across its aft end.

The water heat exchanger is used to heat up water in the hot water tank used for bathing, washing and showering. The hot water tank is fitted with an alarm: when the water temperature rises above 80ºC, an alarm sounds, informing the stoker that it is time to turn the diverter valve on the water heat exchanger to off and to turn off the hot water circulator pump.

There are several good reasons why there are two stoves instead of just one:

• When overwintering on a Quidnon in the far north, hauled out on ice or on shore, and temperatures drop below -20ºC, both stoves would need to be fired in order to to keep the cabin toasty.
• During the warm and hot months in the temperate latitudes, and in the tepid ones, people still want hot water to be available, but lighting the stove in the galley would make it uncomfortable to be in, but the stove in the heads can be used instead.
• Having a large wood-heated cooking surface is very useful when preparing large quantities of food—whether to feed large groups or to process and lay up supplies for the winter—but the one in the heads is occupied by a pile of sauna stones.
• Having a pile of hot sauna stones to throw water on is the excellent, traditional way to generate steam for a sauna.

Above deck, one more flue gas diverter and heat exchanger can be installed to supply heat to a hot box that can be used to dry various things: mushrooms, salted fish, herbs, fruits and berries, clothing and footwear, etc. The hot boxes—one for each stove—can be made in one of two ways: as an easily assembled temporary installation, or as a permanent fixture attached to the bulwarks. In either case, the hot boxes provide additional warm places to sit while out on deck.

Two things need to happen in order to make the Marine Russian Stove a reality. First, with your help, I hope to sanity-check the concept and see if I made any mistakes or omissions. Second, if the concept is sound, comes the step of doing the math and producing the mechanical drawings, and if any of you are knowledgeable about stoves and heating system design and have the interest, I would welcome your input.