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.

Wednesday, May 22, 2019

The Rudder

Rudder assembly
Quidnon’s steering has evolved quite a lot since the original concept. Now all that’s left of the original concept is the idea that the rudder should have a kick-up blade: when sailing across shallows it should gently float up instead of getting torn off or getting stuck, and when the boat settles on its bottom at low tide the rudder blade should automatically get itself out of the way. Only now has a good solution to this problem has finally been found.

Early on it was thought that twin rudders and wheel steering made sense, but this made the design complicated and expensive. Twin rudders require a complicated steering linkage that uses something called Ackermann geometry, which is also used in cars: when turning to the right, the right wheel has to turn more than the left wheel because, being closer to the point around which the car turns, it has to follow a tighter circle.

Later on, after single-handing a 36-foot sailboat from Boston to South Carolina, I discovered that wheel steering is a bad idea and that I prefer a simple tiller. There are very few steering positions that are comfortable with a wheel: sitting behind it and standing behind it are more or less the only choices, and they both get tiresome rather quickly. On the other hand, with a tiller, it is possible to steer the boat while standing, sitting or lying down, using hands, feet and hips, or, with a tiller extension clipped on, with the inside of the knee or the armpit. It is possible to operate the tiller remotely, by tying a bungee cord to one side of it and pulling it to the other side using a lanyard.

In turn, a tiller on such a boat of this size is only workable if the rudder is a balanced rudder, with about a third of its area ahead of its rotational axis, so that the boat can be steered with a fingertip instead of your heel on the tiller pushing with all your might, as is the case with an unbalanced “barn door” rudder that rotates around its forward edge.

Further on, I discovered that Quidnon doesn’t heel enough to make twin rudders necessary: just a single rudder would work fine, and so the design was changed to a single rudder was hung off the center of the transom. But this arrangement was still somewhat problematic. First, the rudder assembly cluttered up the transom and made the boat a bit longer (which is a problem because marinas charge slip fees by overall length). Second, the pivot point of the rudder was too far from the cockpit to give the tiller a useful swing range.

Rudder assembly installed in engine well
And so the rudder was moved from the transom to the back of the engine well, where there is just enough room for it. This made it possible to solve a few more problems.

Quidnon doesn’t always need to have a rudder. It is a houseboat, and houseboats mostly just sit at the dock, where having a rudder is not just unnecessary but also rather inconvenient. The tiller tends to whip around and hit things whenever the tidal current shifts or a boat wake hits. Since it sits in the water, it tends to accumulate marine growth which makes it not work very well when the time comes to move the boat. A better solution is a rudder assembly that is easy to install and just as easy to take out again when the boat is at rest.

Gudgeons in engine well: top view; aft view

With the rudder assembly removed, all that remains on the hull are two gudgeons bolted to the back of the engine well along the centerline. To install the rudder assembly, it is turned 90º, so that the tiller faces directly sideways and lowered into the engine well using a hoist. The rudder shaft has two pintles that engage with the gudgeons. The lower pintle has a longer pin than the upper pintle, so that it can be engaged first rather than having to try to line up two pintles with two gudgeons at the same time.

Once the rudder assembly is dropped into place it can be turned to the 0º amidships position, with the bottom part of the assembly sliding under a recess in the bottom of the transom. This recess serves several purposes: it provides an exit path for the stream from the propeller; it also provides an exit path for the outboard motor’s exhaust when it is in idle (when it is in gear the exhaust goes through the propeller and into the water); lastly, it provides a space for the rudder assembly.

The bottom part of the rudder assembly consists of the rudder blade case and the rudder blade. The case is a box, welded out of mild steel and galvanized, with its bottom and rear open and forming a slot from which the rudder blade protrudes. It is welded to the bottom of the rudder shaft (a steel tube) and reinforced using a triangular gusset. The gusset has a hole in it for attaching a lanyard by which the rudder assembly is hoisted out of the engine well. The sides of the box have specifically shaped cut-outs in them.

The rudder blade is made of a 3/4-inch (20 mm) piece of plywood sheathed in fiberglass and painted. Close to the bottom of the blade is a circular cut-out that is filled with a lead disk, to ballast the blade to counteract the buoyancy of the plywood and to exert a certain downward force when submerged. The top of the rudder blade is surfaced with epoxy that’s loaded with graphite powder, to create a hard bearing surface.

Rudder blade detent mechanism: roller guide and rollers

The rudder blade is joined to the rudder blade case using 4 rollers, 2 on each side, that are through-bolted to the blade and ride inside the cut-outs in the case. The arrangement of the rollers and the cut-outs acts as a detent: in order to get the blade to kick up the force acting on the front of the blade generated by an obstacle has to be more than 4 times the downward force on the blade due to gravity.

The lead disk is sized so that this force is significantly more than 4 times the force generated by drag with the boat moving through the water at its maximum speed. Once this initial resistance is overcome, the rudder blade kicks up rather easily. Once the external force acting on it is removed (because the boat is again in sufficiently deep water) it floats down into vertical position and the roller mechanism clunks into place. When the blade kicks up, it fits in the recess under the transom.

Rudder blade in kicked-up position

The only necessary precaution is to avoid running aground while moving astern: the rudder blade will not kick up backwards. Most of the time the centerboard will strike bottom first, because it hangs down lower, and will stop the boat, shattering if it has to, in which case it will be time to pull the remainder of the centerboard out of its slot on deck and to drop in a new centerboard. But the centerboard somehow misses the obstacle and the rudder blade doesn’t, then the rudder may suffer a bit of damage.

If the bottom is soft and the boat is moving slowly, it will simply stop with the rudder blade stuck in the sand or the mud. If the obstacle is hard or the boat is moving fast, the bolts holding the rollers to the rudder blade, which are designed to be the weakest element, will sheer off and the rudder blade will drop off. Then it will be time to pull out the remainder of the rudder assembly and to dive to recover the rudder blade and the rollers. Then the rudder assembly can be put back together with new bolts. There is also the chance that the rudder blade will strike and damage the prop, in which case it will also be time to pull out the engine and replace the prop. In short, don’t run aground when backing up!

To summarize: the rudder assembly easily installed and easily removed when not in use and for maintenance. With the rudder assembly removed, all that remains in place are two gudgeons mounted to the back of the engine well. It doesn’t kick up unless it encounters a hard obstacle, with no amount of moving water able to displace it from vertical. Its action is fully automatic, never requiring any operator intervention. It provides for fingertip steering using a tiller because the rudder blade is balanced, with 1/3 of the area ahead of its axis. The use of the tiller makes it possible to use the simplest and most affordable kind of autopilot: a tiller pilot that clips onto the tiller. The tiller itself is of a telescoping type, with a handle that slides into its body, so that it isn’t left swinging about the cockpit when the boat is on autopilot.

After all of the various evolutions, I dare say that this rudder design is very close to final.

Monday, May 13, 2019

The Centerboard


Although the Quidnon blog has been quiescent for the past three months, there has been some good progress on completing the design, and I can now report these results and see what comments, ideas and suggestions emerge. It takes time to come up with simple and cheap solutions to complex and potentially expensive problems.

One of the problems that is now solved is how to provide lateral resistance with minimal complexity and expense. The initial concept included chine runners, which are narrow ledges that extended horizontally from the hard chines at which the bottom joins the sides, and two centerboards that hung down from wrist pins and extended from slots in the bottom in such a way that they would kick up into their slots when encountering an underwater obstacle.

The chine runners were discarded when it turned out that Quidnon’s hull, being quite wide in order to provide relatively spacious living quarters (it is, after all, a HOUSEboat), doesn’t heel enough to allow the chine runners to bite into the water. All the chine runners did was add some drag (and, of course, complexity and expense).

The kick-up centerboards worked well enough, but there is a basic problem with them: since they hang down from a hinge, they are deflected when moving through water, and this makes for erratic steering behavior. The deflection can be minimized by adding ballast, but this makes the boards too heavy. It is also possible to add tensioner lines fed to cleats that pop open when the boards hits an obstacle, but this adds complexity.

The problems with the original centerboard design didn’t end there. How does one remove them for maintenance and cleaning, and put them back in? If this required the boat to be hauled out, then that would invalidate the very important requirement that Quidnon must never need hauling out (haulouts are expensive!). The copper cladding can be cleaned with the boat hard aground at low tide and there is nothing else down there that should ever need attention. And so a plan was created for installing and removing the centerboards with the boat in the water with the help of a diver. But divers are also expensive!

And then another good question arose: why are there two boards? Well, the initial thinking went as follows. Putting a single centerboard along the centerline wastes precious living space in the middle of the cabin by filling it with a centerboard trunk. Moving it off to the side makes the design asymmetric, and that’s functionally unimportant but aesthetically unpleasing. Therefore, let’s have two of them. The flaw in this logic is that the aesthetic consideration matters not at all because the centerboard isn’t visible. Your heart is on your left and your liver on your right, but nobody will ever call you ugly because of that.

If two centerboards are too many, how about zero centerboards? Well, it turns out that having a centerboard is rather important, but only when the boat moves. It is especially important when motoring in and out of marinas, because without the centerboard the boat will drift sideways instead of turning within a tight radius. It is also important when motoring, especially upwind. It is sometimes possible to sail downwind without the centerboard, but that’s about it. But if the boat doesn't move (as houseboats often don't) then a centerboard isn't needed at all, and having one that's quick and easy to install and remove would be a bonus.

And so just one centerboard is both necessary and sufficient. It will be located off-center (to starboard) with the centerboard trunk located unobtrusively in the back of a settee in the salon, sandwiched between it and the water tank. (But we’ll still be calling it a centerboard because offcenterboard is not a word.) The centerboard trunk forms an L-shaped slot that extends from the deck all the way to the bottom (and does extra duty as a deck drain). To one side of the slot is a channel that stops short of the bottom and tapers in a specific way before it stops.


The centerboard is just a piece of 3/4-inch plywood covered with fiberglass for durability. A circle is drilled out of it near the bottom and filled with lead in order to make the centerboard heavier than water, but not much heavier. It doesn’t have to sink particularly aggressively; it just can’t float up. To one side of the centerboard, near the top, is screwed a cam that rides inside the channel on the side of the centerboard trunk. At the very top of the centerboard is a hole used to attach a lanyard by which the centerboard is retrieved. If the lanyard breaks, a boathook can be used to grab the board by the hole. The centerboard is sacrificial and designed to snap without causing damage to the hull. Making a new one is neither expensive nor difficult.


The centerboard will spend most of its life sitting flat on deck. When the boat is getting ready to move, it is installed by unceremoniously dumping it into its slot.


If there isn’t enough water under the boat it won’t go all the way down, but that’s usually not a problem. (You may need to give its lanyard a tug when backing out of a shallow berth, to keep it from catching on things.)


When the centerboard hits something underwater with the boat moving forward (as boats normally move) it deflects aft, but in order to do so it needs to ride up a bit, so that the cam moves up inside the tapered slot. It can stay in this semi-retracted state, bouncing along the bottom, while the boat sails or motors across shallows. This will slow the boat down a bit, but will also provide good steering because the boat will pivot around the board as it digs a shallow trench in the sand or the mud of the bottom.


It is not necessary to remove the centerboard when anchoring above the low water line with the intention of drying out at low tide because it will be forced up entirely into its trunk.

This completes the conceptual design of the centerboard; next on the list are: the rudder; engine mount; mast steps and bow structure. These have all been reworked, and I will be detailing the new designs over the coming weeks.

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.