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.

Tuesday, December 27, 2016

Surviving Winter Aboard

Life aboard can be perfectly pleasant when it’s warm outside, but when the weather turns cold a number of unpleasant factors conspire to make most sailboats, power boats and houseboats uncomfortable. This article attacks the problem from three directions. First is an explanation of all the factors that make overwintering aboard a typical commercially built recreational boat rather unpleasant. Next, I describe how those intrepid souls who do overwinter aboard in northern climates cope with these factors. Last, I describe how all of these factors are carefully avoided in the design of QUIDNON, “a houseboat that sails.”

Typical Problems

First, the vast majority of boats is badly insulated. In most sailboats, the windows (deadlights, portlights and hatches) are concentrated on the cabin top, and are single-glazed with just one layer of transparent plastic. Warm air rises, heat concentrates under the cabin top, and is then efficiently conducted to the outside. The sides are generally not insulated at all, causing a cold downdraft to bathe the backs of those seated in the salon. The bilge is not insulated either, meaning that the cabin soles are close to the same temperature as the outside water, which in the colder climates tends to linger around the freezing point for several months.

Although the volume inside the boat is quite small compared to a house, theoretically making it easy to heat, the lack of insulation makes the space feel cold even if the air temperature right under the cabin top is uncomfortably warm. When seated in the salon, which is how people tend to spend most of their time, their feet are freezing-cold, their backs are bathed in cold air, and their heads are hot. This is not particularly comfortable.

The second major problem is condensation. The human body evaporates water through the skin and through respiration, and all of this water condenses on cold surfaces. When it condenses on the various windows, it then drips down on whatever is directly below them. Few things are more unpleasant then feeling a trickle of freezing-cold water on your head or neck as you are trying to sleep. This indoor rain can also destroy laptops and other electronics. When it condenses on the sides of the hull, inside lockers and other spaces, it causes mold to grow there. If you are lucky, it is white mold, which washes out; if you are not, it will be black mold, which leaves an indelible stain and can sicken people.

The condensation problem is made much worse by cooking, or even boiling water to make tea, which dumps a lot of moisture into a small volume of air. Most sailboats are not equipped with vent hoods over the galley range, and the only option for getting rid of the excess moisture is to open the companionway hatch. But this causes virtually all of the warm air trapped inside the cabin to immediately escape outdoors, making the cabin unbearably cold.

Condensation affects all the objects stored inside the cabin. Clothing becomes dank and moldy unless it is kept in tightly sealed plastic bags or containers. Bedding and mattresses becomes saturated with moisture, making it impossible to get warm at night, while a lack of dry sunny days makes it impossible to dry it out by hauling it out on deck during the day. Books becomes warped and papers roll up into tubes. Envelopes seal themselves shut.

Another problem with overwintering aboard is the smell. When it is warm outside, the boat can be very well ventilated, making it less of a problem. But in the winter, with everything sealed tight to keep in the warmth, a boat quickly develops a musty odor, or worse. It is exacerbated by pockets of mold which develop in hard-to-reach pockets and crevices between the hull and the interior cabinetry. A cat litter box, used by just one small cat, can make the smell unbearable. Polite acquaintances decline invitations to visit you; rude ones say things like “Oy, what’s with the bloody pong?”

Often, a major source of the smell is the sanitation system. The toilet and the holding tank themselves are rarely the problem, because they are vented to the outside and made of materials that are largely impermeable to smell. More often, the problem comes from the use of sanitation hose used to plumb the system together. The installation is almost always an afterthought, with components crammed in wherever there is space for them and linked together using generous lengths of reinforced vinyl hose, which blocks liquids but not smells and quickly begins to stink all the way through. On one boat I noticed that the cold water tap in the heads has a very distinctive smell when it was first turned on which quickly disappeared. The culprit, it turned out, was a single zip-tie, added by some person in a futile attempt to keep the bilge tidy, which clamped the cold water hose tightly against the sanitation hose that ran through the bilge. I snipped the zip-tie, and the smell gradually went away.

Some number of live-aboards favor composting heads over the conventional ones with holding tanks. These accumulate solids in a vented bucket, allowing them to decompose down to soil. They tend to work reasonably well during the summer, but in the winter months, when air in the cabin, and especially in the head, becomes saturated with moisture, the solids in the bucket never dry out, and are liable to become infested with all sorts of nasties. My least favorite are tiny black flies which don’t bite but find their way into everything—a less than appetizing development given where they’ve been.

Yet another unpleasant aspect of spending winters aboard is that the cramped environment of the typical sailboat cabin, which is essentially a tunnel, produces claustrophobia and can lead to cabin fever. Some of the cramped conditions on a sailboat are there by design, and are unnecessary. One of these is the division of the deck into side-decks and a cabin top. The side decks cut in on interior space, producing the feeling that the walls are coming in on you. Another is the choice of a pointed bow, which forces the forward cabin into a wedge-shaped “V-berth”. The cramped conditions are exacerbated by the common choice of dark wood paneling instead of cheerful bright-colored paints, which makes the cabin cavernous and dark. Nor is the situation helped by the small light fixtures commonly used on sailboats, which are unable to dispel the gloom.

All of these things are potentially quite unpleasant, but generally sublethal. But winters aboard offer some nastier surprises, in the form of snow and ice. A good-sized winter storm can pile enough snow and ice on deck to make the hull ride low in the water, submerging through-hulls that are designed to be just above the waterline. If the water trapped inside the through-hulls then freezes (there is usually a lens of fresh water floating on top of salt water, and it freezes first), it can burst the hose just inside the through-hull and flood and sink the boat.

In many cases the leak from a cracked through-hull or a burst hose is small enough for the bilge pump to keep up with it, but what if the bilge pump is frozen solid? Even if the cabin is heated, the bilge pump, sitting far down in the bilge, does not benefit from any of this heat. If seawater temperature outside is just below the freezing point for fresh water, then the water in the bilge, being composed mostly of fresh water from condensation, can freeze, and the bilge pump will blow fuses and refuse to turn.

And even if the bilge pump does work, what if there is no electricity to power it? Snow storms often cause power outages; at one marina where I overwintered the transformers on the dock got drowned and blown out by the storm surge, and power remained off for days. A few boats have solar panels which can power a few vital systems in a pinch, but there is no sunlight available during a snowstorm. Some boats have wind generators, but what if the snowstorm is also relatively windless?

Even if no through-hulls fail and the bilge pump runs, when electricity goes off many people find it impossible to keep the boat warm enough to keep the on-board plumbing systems from freezing and bursting. A few higher-end boats have diesel-powered heating systems that provide an autonomous source of heat (as long as there is diesel in the tank); in others live-aboards install propane heaters (which must be vented through flues, since propane burns to carbon dioxide and water vapor, which exacerbates the condensation problem. But many people who overwinter aboard use electric space heaters.

And that leaves only two ways to cope: winterize the plumbing systems by flushing them with antifreeze and drink out of a jerrican all winter, or keep the plumbing systems running and bet on being able to keep the boat warm enough all winter. The problem with winterizing is that in the dead of winter water tends to get shut off for periods of time, and people who don’t have access to their own water tanks lose all access to water.

The last problem worth mentioning is sea ice. If it gets cold enough long enough, ice can form all around the hull and crush it. At one marina in Boston, when a cold snap was preceded by a wind storm, all the boats froze in while listing at a 10º angle, leaned over by the force of the wind, and remained stuck that way for a weak. People didn’t much like living with their entire world tilted. But the ice didn’t get thick enough to crush any of the hulls.

Typical Solutions

Most people who overwinter aboard choose to shrink-wrap their boats. Some hire contractors, while others organize with their neighbors and pool resource to buy shrink-wrap, propane-fired heat guns and other supplies. Most people try to get their shrink-wrap up by Thanksgiving. Having the entire deck of the boat cocooned in plastic makes it much better insulated by eliminating wind chill. It also provides quite a lot of free heat—during the day—by trapping heat from sunlight. Sometimes this greenhouse effect gets to be too much, and by the end of March, when the nights are still too cold to take the shrink-wrap off, daytime temperatures under the shrink-wrap can become uncomfortably hot. People end up cutting holes in the plastic to vent off some of the heat during the day, and then put up with the resulting chill during the night.

Most of the work in shrink-wrapping a boat goes into erecting a ribbed skeleton to support the shrink-wrap. After numerous failed experiments with PVC, bamboo, dimensioned lumber and other materials, it has been conclusively demonstrated that the best material for the job is electrical conduit, with lots of ribs holding up a backbone. The problem with it is that all of this bulky bent tubing has to be stored somewhere during the warmer months. I’ve successfully used a different approach: instead of building a frame, I simply built a strong backbone out of dimensioned lumber, supported it using the mast and propped up using posts elsewhere, and then ran lots of straps to the gunwales.

Shrink-wrapping the boat provides insulation for the deck but leaves the sides uninsulated. Here, a number of different approaches have been tried. There are two main difficulties with insulating most hulls. First, it is very difficult to get insulation into some of the more awkward and hard-to-reach spaces. Second, most hulls are designed with compound curves (concave on the inside, convex on the outside) whereas most cost-effective insulation materials come in flat, sheet form, and crafting complex curves out of flat stock is a geometric exercise that is beyond most people’s skills.

The easiest to insulate are the deadlights, portlights and hatches, which leak the most heat and cause the greatest nuisance by dripping condensation. In the mid-Atlantic states, where freezing temperatures are rare, it is often sufficient to cover them with a layer of bubble-wrap held in place using transparent packing tape. This prevents them from leaking heat and dripping while still admitting plenty of daylight into the cabin. In colder climes, the hatches can be insulated by force-fitting them with polyurethane foam plugs and sealing them on the inside with radiant barrier mounted on double-stick tape.

Although the problem with condensation, and the resulting mold, is chronic on many boats, especially in wintertime, many people have figured out how to keep mold under control using vinegar and tea tree oil. A gallon of white vinegar is enough to wipe down the inside of every locker, cabinet and enclosed space in a good-sized boat. A good technique is to spray it around using a spray bottle, then wipe with a sponge. Vinegar is an acid, and fungi does not like acids. Where vinegar fails to dissuade them, tea tree oil finishes the job.

I have had mixed results with composting toilets, especially in wintertime, when the condensation in the cabin causes solids in the compost bucket to turn to liquid and to come alive with various unwelcome guests. At various times, I have found myself dosing that bucket with various substances: pete moss, Spanish moss, wood chips, mulch scooped up from under the bushes in a nearby city park, boric acid… What worked best, of all things, was a substance called diatomaceous earth, which contains the fossilized remains of tiny marine organisms—diatoms—which function as miniature razor blades, slicing up the waxy bodies of insects and insect larvae. And what worked best, hands down, was dumping the whole mess into a contractor-grade garbage bag and tossing it in the marina dumpster, and then using the marina’s toilets from then on.

I have also had mixed results with keeping the bilge and the plumbing system from freezing, and many a plumbing a fixture have I been forced to rip out and replace with… stuff from the garden supply section of the local hardware store. Along the way I found out that a few small water leaks here and there are actually beneficial. A water leak from the hot water heater can keep the bilge pump from freezing. When hooked up to shore water, it is very helpful to leave all the taps running a little during the colder nights. Keeping the water moving effectively dissuades it from trying to crystallize.

Some marinas have winter water systems that use hose submerged under the floating docks, so that they do not freeze. The challenge there is to get the water to the boat without having it freeze. The recommended solution is to wrap the length of hose exposed to freezing air in heat tape (plugged into the AC system) and thermal insulation. This works well enough as long as there is shore power. A common design flaw is to put the connector for the shore water hose nowhere near the waterline, requiring a much longer run of heated hose than should be necessary.

Where ice gets thick and solid enough to endanger crushing the hull a common solution is to run bubblers around it, to keep the ice from forming. I haven’t had any experience with these bubblers, but apparently they do work, although they suffer from the same worst-case-scenario problem as other on-board systems: what happens when the electricity goes off for an extended period of time? Then the drill becomes to go out every few hours and manually smash the ice all around the boat.

QUIDNON’s Approach

The purpose of the design exercise that is the QUIDNON project is to take our decade of experience living aboard in various conditions, from subtropical summers to northern winters, and accentuate the positives while eliminating the negatives.

The first negative to eliminate is the bad distribution of heat. The first step is to insulate the sides, the deck and the transom. This is best done using 1.5-inch foam, which comes in 2x8-foot tongue-and-groove slabs, and radiant barrier, which comes in rolls of various widths and lengths. Both of these materials are quite cheap for the quantities needed, and easy to install because QUIDNON has just three curved surfaces—the bottom, which doesn’t need to be insulated except at the bow where it comes up out of the water, and the sides—and these curved surfaces are planar rather than compound curves.

The easiest procedure for installing the radiant barrier, which is essentially bubble wrap that incorporates aluminum foil layers, is directly onto the hull surfaces using double-stick mounting tape. The slabs of foam insulation can then be cut exactly to size and press-fit into place with a bead of expanding foam all around, for a tight seal. The foam can then be covered with thin (1/8-inch) plywood sheets. Light-colored plywoods, such as birch and white pine, can be polyurethaned (on both sides, to seal the wood); darker shades of wood should be painted white or off-white, to avoid creating a gloomy atmosphere.

I have used this procedure on two boats so far, and it made a big difference. Whereas before the cabin felt cold and drafty when heated to 70ºF, with the insulation in place it felt reasonably warm at 62ºF.

The next problem to tackle is distributing of heat around the cabin. If this is done badly, the result is cold feet and an uncomfortably warm head. QUIDNON’s solution is made easy by the distribution of cabin soles: the two lowest points are the galley and the heads, where heat is generated in the form of warm air using electricity, propane or solid fuel (the difference is essentially in the choice of firebox). This warm air is then injected under the cabin soles in the galley and the heads. All of the spaces below the cabin soles are interconnected by openings in the bulkheads and partitions which separate them, allowing the warm air to rise to where it’s needed, aft to the aft cabins and forward into the salon and the “U-berth”, and from there to the various lockers and other spaces, making sure than every space and every surface inside the boat is warm and dry. To reduce the amount of heat that is conducted overboard through the bottom, the bottom is lined with a layer of radiant barrier.

This technique of distributing the heat starting with all of the enclosed volumes and finishing with the habitable space reduces condensation by a large amount, eliminating pockets where mold can take root, but there are two other condensation-related problems to solve. The first is to make sure that the deadlights and the hatches don’t drip condensation on whatever happens to be below, people and laptops especially. This is achieved by double-glazing all of the portlights that wrap around the entire boat, just under the flush deck. A thick round plate of polycarbonate plastic is caulked and screwed into place on the outside; a much thinner layer of the same is screwed in place on the inside but is not caulked so that air pressure inside and outside the deadlight is allowed to equalize. The large main hatch in the deck, which is right over the salon table, is also double-glazed. Here, the inner layer is perfectly airtight, while condensation that forms on the outer layer is provided with a trickle path that leads onto the deck rather than into the cabin. One last window—the one in the companionway door, which slides down into the chain locker when open—is single-glazed, for the specific purpose of attracting all of the condensation and allowing it drip down into the chain locker and from there run overboard.

The problem of excessive moisture produced by cooking and showering is dealt with by providing exhaust fans in both the galley and the heads which vent through two flues. In the galley, a vent hood eliminates moisture and smells coming from the stove; in the heads, an exhaust fan eliminates water vapor from showering and the inevitable smells.

The smell coming from the sanitation hose that connects the toilet to the holding tank and the holding tank to the pump-out fitting on deck is eliminated by not using sanitation hose at all. The toilet is placed directly on top of the holding tank, which is a sheet metal box with a screw-down lid that serves as its pedestal. It is connected to the pump-out fitting on deck using a steel pipe, not hose. None of these are the least bit permeable to smell. With a bit of cleverness and the flush toilet replaced with one that separates liquids from solids the same arrangement can be used for a composting toilet. Although composting toilets have certain merits, being able to put your QUIDNON on AirBNB, if it is outfitted with one, is not one of them.

The problem of a sailboat cabin being dark, cavernous and cramped is dealt in a number of ways. The paneling inside is not stained and varnished but painted using very durable two-part polyurethane paint. The flush deck adds lots of airspace under the deck, and eliminates the effect of the walls coming in on you created by the side-decks. The feeling of spaciousness is further enhanced by the full headroom in most of the cabin (the sleeping areas in the aft cabins, the pilot berths and the U-berth are the only exceptions). The many deadlights and the large main hatch admit plenty of daylight, while at night the darkness is dispelled by long strings of lights mounted along the inside edges of the deck, producing a diffuse glow that accentuates the considerable (by boat standards) interior volume of the cabin.

QUIDNON deals with the considerable nature of through-hulls under or close to the waterline by not having any. There is no inboard engine, and therefore no propeller shaft and no seals to go with it. Nor is there a raw water intake for the engine. The raw water that is used as ballast is pumped in through siphons that are lowered down into the engine well.

The problem of a frozen bilge, and a frozen bilge pump, is resolved by not having a bilge at all. The bottom is flat, and although a bilge pump is mounted at its lowest point, it virtually never runs unless there is a leak or a spill. The shower stall has a separate sump and bilge pump, which pumps water directly overboard.

The problem of keeping the boat from freezing when severe weather knocks out shore power is solved by providing a variety of alternative sources of heat and hot water. Under normal conditions many people will decide to heat with electricity. It is more expensive, but less bother. If shore power is unavailable, the next fallback is propane. There are two propane tanks in the propane locker: one for the galley range, the other for the heaters. More tanks can be stored on deck. If propane runs out, the fireboxes can be converted to run on solid fuel (by sliding out the propane burner and sliding in a grille and an ash box) and kept burning using wood or charcoal. (Not all marinas allow the use of solid fuel, but it’s usually possible to get away with it in a pinch by not telling anyone.)

Much of the expense and the difficulty of shrink-wrapping the boat is eliminated by making it very easy to enclose all of the deck space between and including the two deck arches. The roof and the sides are created by lacing the tops of the arches together using rope, then draping a tarp over the entire structure. From the front and the back, the space is enclosed using two large curtains. The enclosed space is large enough to provide extra storage and living space. An additional curtain hung over the entrance to the dodger that encloses the companionway hatch will prevent warmth from quickly escaping from the cabin when the companionway hatch is opened. The area forward of the forward deck arch, which includes part of the main hatch, is best kept open, to be used as a patio on the warmer days.

With all of of these systems in place and functioning, QUIDNON should make a for a perfectly pleasant winter sojourn even in the snowy north.


  1. Where reliable grid power is available, here are a few cheap tricks for heating people directly...
    Also, I've found that electric heated mattress pads are enormously effective, as are incandescent light bulbs in a reptile reflector.

    But on a loosely related note, Dmitry, I read in an article some months ago about a Russian hot water appliance called a samovar. The article was about how this simple little water heater contributed to the Russian military defense advantages during wintertime, by allowing both the countrymen & the soldiers to warm themselves from the inside out during resource scare periods (which describes warfare well), thus reducing their need for both heating fuels & calories from their diet.

    Anyway, I bought an electric water heater for my countertop, that keeps 5 liters just shy of boiling all of the time. It works great for it's purpose, and I have found that a hot cup of tea is a great way to knock the winter chill off as I come in from work. But it wouldn't work well on a boat; at least not without constant grid power and securing the device to the bulkhead. Is there anything like a samovar that can be used on Quidnon? Perhaps with the additional use as the sauna boiler? I'm looking for suggestions from anyone.

  2. Yes, electric blankets placed under the mattress and kept on all winter are very useful in keeping the mattress and the bedding dry and making the bed much more pleasant to get into.

    There is a wild profusion of samovars available, both electric and charcoal-fired.

    1. A lot of those are beautiful, and terribly impractical. I was thinking along the lines of a propane or charcoal fired samovar that can be secured to the boat. I can't read that page, but it doesn't look like any of those would qualify.

  3. Dmitry,With respect. I live on a sailboat for many reasons. Near the top of the list is this one. I live where the weather is beautiful. Not good. Beautiful.Love your work and admire your hardy Russian polar bear genes. Hope to meet you in the Caribbean someday. Sincerely,James K S/V Udo

    1. Agreed, maybe easier to move the boat South.

      s/v Django

  4. We have had used an aquarium heater in the bilge to keep it and the pump/float assembly from freezing. It has worked for the last 3 winters.

    s/v Osprey

  5. Crikey, Dmitri, this post reminds me of so many things on my boat. Fortunately (?) it lies in the increasingly-temperate climate of modern Britain, so the cold spells, such as they are, don't cause much of a problem. Glad I'm not in New England. My liquid-separating composting loo - with dedicated composting bins ashore - doesn't usually suffer from long below-freezing periods, so no problems there.

    1. I hear that, if climate change proceeds as is expected, the shores of Scotland will be a nice place to vacation soon...

    2. But they are already, Free2Rhyme. You just need to keep your raincoat with you at all times...

  6. I'm looking forward to seeing some more graphics to flesh out the Quidnon and the physical model in the water. Thanks, Dmitry.

  7. Getting an early Quindon model has been my dream since you started blogging about it. I was recently wondering about wintering on boats for this reason. Since I am not a sailor, and live a couple hundred miles from the seashore, I was recently daydreaming about building it on the Great Lakes, where I wouldn't be subject to the full fury of the sea while I learn to sail. The winters would be hard!

    1. One of the advantages of QUIDNON is that it can function as a beach house when hauled out. It can be rolled ashore over logs, after dumping the ballast (emptying the water tanks, dropping the external ballast box). On the Great Lakes I would certainly recommend spending winters on shore, hauling out before the ice starts setting up and floating off again once the ice is all gone.

    2. You don't have to winter the Great Lakes either. My plan is to 'snowbird' by summering on the Lakes and then floating on down the Mississippi River during Autumn, to end up rounding Miami, Florida about New Year's Day, then up the East Coast during Springtime. It's called the Great Loop, and Quidnon looks perfect for it.

    3. We just finished the Great Loop on an Oday 34 and I agree that Quidnon seems ideal for this route.

    4. Which post details the external ballast box mentioned above?

  8. How would winterizing work? I note that Quidnon can be hauled out, but sticking with the example you mention from Boston, what would need to be done to leave Quidnon unattended or semi-unattended in a Boston marina with freezing seawater and sea ice? I'm mostly wondering about the water bladders.

    How would sewage disposal work with no shore power or post-collapse?

    1. If the boat is to be left unattended over the winter in Boston, at a marina, I would recommend draining both the water ballast and the fresh water and flushing the pipes with RV antifreeze, just to make sure none of the pumps and valves get damaged.

      In many parts of the world sewage is pumped directly overboard. This is not difficult to arrange.

  9. These are good features to use even if not considering a Quidnon and designing your own vessel. I second a above comment on merely celebrating one of the very coolest attributes of a (relatively) easily relocatable home: dwell in great micro-climates. And in that vein perhaps a post detailing heat and insect strategies? Buzzing mosquitoes destroy even the most idyllic anchorage when it comes time to turn in. Another good reason to anchor in a strong tradewind area.

    1. Those who want to design their own vessel should definitely consider getting their own blog on which to do it. Insects are indeed a problem. Dorade vents can be insect-proofed by installing wire mesh, but they don't deliver enough air in hot, relatively windless weather. Putting insect screens into hatches is a possibility, and QUIDNON will certainly make that possible. But the major advantage of QUIDNON as far as bugs is that it has deck arches, which capture plenty of wind from most directions and funnel it directly to the the places where people are most likely to sleep: the two aft cabins and the two pilot berths. Between the deck arches and the main screen hatch (which can be partially opened in one of 4 directions, to best capture the wind) QUIDNON should be quite comfortable even on the hottest nights. If there is no wind at all, the 12V electric fans built into the plenums that release air from the deck arches should cool things down nicely. The final resort is to get a box air conditioner and stick it in the companionway.

    2. Dorades work fine if you use the "old" dorades.

      For every dorade venting at cabin top, one dorade vents at bilge level.

      This, like a cold cellar, creates a convection current and draft, even if there is no wind.

    3. These features are well thought out and valuable. They deserve adding to sound design tenets in about any small hull for personal use. Things to consider when pondering a new design or a old one.

  10. A few downsides of foam insulation:

    1) Flammable
    2) May lose insulating capacity as it ages
    3) Susceptible to mold and critters

    An alternative that I am looking at for my house is mineral-wool insulation (Roxul), which is a fibrous insulation like fiberglass but made from iron-slag. Advantages:

    1) Fire-proof (used in industrial applications for that purpose)
    2) Doesn't off-gas, doesn't lose insulating capacity
    3) Supposedly not susceptible to mold, not attractive to critters
    4) Does not absorb water, allows it to drain
    5) Sound-deadening (also used in industrial applications for that purpose)

    The Roxul batt insulation is like a firmer fiber-glass, more like a loaf-of-bread texture, but that wouldn't be useful to replace the foam. Roxul also makes a board style insulation (Roxul ComfortBoard) which might work in place of foam. I don't think it would provide a firm base for plywood paneling though, you might need furring strips to hold the paneling just like you would to attach siding to a house over the Roxul boards.

    The fire-resistance and sound-deadening traits seem especially appealing in the context of a house-boat.

    I can't quite visualize the place of foil in your system so this may be irrelevant, but I played around with the radiant foil barriers in my house and was eventually convinced that it is better to just use extra regular insulation instead. Seems the foil is only effective when next to air gap, and even then it stops working if it gets dusty.

    1. Foam hold up for the lifetime of the boat (~30 years). Critters don't eat it. It burns no better than anything else inside a wood/fiberglass boat, so fire protection is in the choice of fire extinguishers, not in the choice of materials. Your proposed material would have to hold up after being repeatedly dunked in water and dried out. Not sure it's worth the trouble to try it. It may be better, but foam insulation (pink or blue) is good enough.

    2. Roxul Comfort Board is a foam board replacement.

      Like Thinsulate, it has it's advantages and it's disadvantages.

  11. I hope you'll "open source" this design! (After it's built & proven of course.)

    1. No, the idea is to sell kits for rapid DIY construction of houseboats that sail, which is something that currently doesn't exist. The last thing we want is for somebody to take all of our hard work, "fork it" and build flawed knock-offs, ruining the project's reputation. We'll make some free (though copyrighted) study plans available, but that's about the limit of what's realistic.

  12. Great ideas! I think those hoods/extractors are going to be invaluable.

    Here are some more to consider...

    Alaskan liveaboards on S/V FOOTLOOSE wrapped foamboard in vinyl wall paper, making removable, block insulation. I saw it after 10 years and looked great! Very resistant to pokes and easy to wipe down. Might be useful in some areas.

    We'll be trying a metal stack next to our heater, closed at the bottom, and plumbed to the locker system. These will be open on the far end and conduct open, one to the next in a circuit. As the stack heats, it will draw air flow through the lockers.

    THE WARM DRY BOAT by Roger McAffee suggests employing 'a sophisticated aeroflow sensor' (cigar or incense stick) aided by a good beer, for observing airflow patterns with various hatch openings under various conditions.

    Dave Z

    1. Hi Dave,

      Using wallpaper instead of plywood to dress up foam insulation is brilliant. That'll be the base option; people can get as fancy with wood veneer as they like, of course. It's amazing how many little tricks like that there are, and they all add up over time. Thanks!

    2. If we used a couple of those custom wallpaper sets, sometimes called a Photowall, using images of important charts of our intended areas, and perhaps a lanyard attached to each, these insulation panels could double as emergency flotation.

  13. Coanda , a Columbia 26 had some winter mods.

    Including the bilge, the hull was lined with HDFC insulation, which as it's closed cell, can be used below the waterline with out water saturation that is common with foam core material.

    As the boat had '60's style plexiglass windows, ( unopenable), I replaced them all with sealed acrylic double panes, filled with argon and with cut outs allowing the addition of small portlights for ventilation.

    Deck hatches were similarly "double paned", then insulated with a couple layers of bubble pack and a snug down bag of transluscent nylon.

    Solarvents with rechargable batteries were placed in the head and in the galley.

    Two small, modified Force 10 heaters were installed in the cabin. The modifications consisted of having the combustion chamber sealed off and a fresh air inlet added. One burned pressurized kerosene, the other, Douglas Fir bark chunks. Propane burns "wet", kero, neutral, wood, dry.

    The stoves were attached to 1 1/2" granite countertop scraps on an airgap to act as a fire barrier and a heat sink/thermal mass.

    Laptop fans were attached through bulkheads, powered by small solar panels to circulate air.

    All interior closet doors, cabinet doors and drawers were louvered for airflow.

    The three burner stove and oven was kero, a diesel stove is better for dry heat.

    The Cockpit was covered with a modular dodger/bimini/cockpit tent for added space, warmth and light. Usefull in summer as well if fitted with mosqueto screens.

    The forward areas were covered with a light waxed canvas cover, one over the boom, lashed to the lower lifeline, the other, forward to the mast over a mast to bow line, with snaps to tie the two together to keep snow and ice off the decks.

    There was a solar array off the transom, a removeable array on the bimini, and 6 hung off the upper lifelines with adjustable legs to allow them to be angled properly. 2kwh works really well when your lighting is LED, and entertainment is a CD player and laptop.

    The propane hot watertank was modified to be super insulated, ( propane/engine freshwater), and a simple pex bilge heating system was added, off an automatic thermocouple, for long windless days under engine power.

    It helps sometimes to buy a POS headed for the breakers and rebuild from scratch.

    Did a couple of winter trips to southern Alaska. Good times.

    1. Hi Jay,
      What thickness and system of insulation, glued on board stock, sprayed on,..., did you select?

      I have been planning on replacing the H/C water hoses with pex, and now the bilge heater!

      Did you only heat your deep/wet bilge?

      Helen & Joe
      s/v Osprey

    2. Helen and Joe,

      When I bought Coanda, she had a horribly installed Volvo, a water soaked rudder, a blistered and rusting iron keel, a trashed interior, rotten deck core, leaking fittings, dozens of uncaulked deck holes and simple deck hatches of cracked and yellowed plexiglass over wood frames.

      It was a project bought for the scrap metal value.

      As the Columbia II's had a reputation for "oil canning" in places, I ripped out the interior liner, bulkheads and furnature completely.

      I epoxied in a series of "ribs" made from 1" Fiberglass Pink High Density foamboard, ( only use epoxy, the acetone in fiberglass resin will melt foam), covered with 3 layers of 8 ounce glass cloth, set about a foot apart. I did the same with "stringers" up the hull sides and under the deck.

      I then cut and fit in chunks of the 1" foamboard, ( grid scoring the back 3/4's of the way through so it would "bend" to the hull shape) and glued it in with a thickened epoxy.

      Over that I glued in "Reflectix" heat barrier, ( the mylar and bubble pack product), then installed a "canoe cove" wooden ceiling, screwed into the "ribs", ( a la Don Casey's This Old Boat).

      I made bulkheads and furnature frames out of full sheets (4x8) of the Fiberglass Pink foamboard, laminated with two layers of matt and glass, and on the "presentation" side, where I wanted wood, a layer of veneer.

      It worked well for me, because I wanted a custom interior anyway. The Columbia 26 II's interior was set up for maximum numbers of bodies, not seakeeping.

    3. Oh, btw, the pex was run as a "radiant floor" heating system. The bilge was fully insulated and dry.


    Closed cell, doesn't out-gas, fire retardant, mold resistant... floats!

    1. Meets US Coast Guard Title 33 Specification (p. 183.114)
      ASTM-E84 (American Society for Testing Materials)
      Flame Spread = 20 / Smoke Developed = 200 / Perm = 1.2 @ 3″
      Fuel and water resistant
      International B2 Fire Rating
      Complies with U.S. Clean Air Act & Montreal Protocols
      CHEMTREC #201586 – 800.424.9300
      CCMC #13484-L
      ICC ES Report # ESR-3183

    2. This stuff makes sense for steel hulls. Plywood and fiberglass hulls are not particularly flame-retardant, so adding flame retardant foam makes no difference. Pink Panther foam and radiant barrier work great, easy to install, easy to remove.

    3. An issue with sheet type foam is when air gets behind it (on the cold side). Condensation will build up between the hull and insulation and is slow to dry out (mold risk). Even a small air leak will cause an amazing amount of condensation, and ice build-up if the hull is cold enough. I insulated my chest freezer with the pink foam board and had to go back and seal the joints completely to prevent condensation. BTW: all of these spray foam products meet flame resistance codes, but not all are closed-cell (some absorb water.)

    4. Yes, a tight fit for the foam is necessary to avoid condensation issues. My technique is to cut it so that it is press-fit into place with quite a bit of force. Going over the inner surface with tea tree oil helps, as does laying a bead of caulk around the perimeter.

    5. With many fiberglass boats being constructed of a molded hull, molded deck, molded liner and molded headliner, glued or mechanically bolted together, using expanding foams to fill the gaps in-between can cause problems.

      If the foam over expands, you get buckling and breakage.

  15. Why don't boats use heat recovery ventilators? You'd only need a small one for that space. Odors and excess moisture would be gone. The one we added to our house made a huge change in air quality.

    1. He's been talking about being at dock in the winter and using electric heat. Surely there's enough left over for two small fans.

    2. Probably so, while connected to grid power. But heat recovery ventilators often include a small heat pump, and are a bit more complicated than two fans pushing air past an air-to-air exchanger. I'm sure you could try it, and the vents in the deck arches might come close to that anyway; but adding such a thing to the core design would violate the 'more than one function' rule. What other purpose would such a machine serve on a boat?

  16. The FanTech one we have is just two fans, heat exchanger, and a small computer board to run it.

    1) remove humidity
    2) ventilate head
    3) ventilate galley
    4) make wind chime sound during calm weather

  17. Are you insulating the floor above the bilge or do you plan on investing in slippers?

    1. The cabin soles will not be insulated, they will be heated by pumping warm air into the bilge. It may make sense to insulate the bilge, though.

    2. I had a thought about making one of the lockers into a "cool box" by insulating the sides and top, but not the bottom as it is attached to the sole. It would rarely, if ever, be as cool as a true fridge; nor could it be regulated. However, a great many things that Americans keep in the fridge do fine as long as they don't spend much time above 60 degrees. Such items include most types of condiments, including mustard & ketchup; pretty much every kind of 'hard' cheese I can think of; most anything in a jar that says "refrigerate AFTER opening"; butter, particularly the salted butter; even fresh eggs for a time. Again, if you spend a lot of time in the warm waters South of 30 degrees, this isn't going to be a very useful feature. But for everyone else, this would be useful most of the time; including the dead of summer on Lake Michigan.

    3. What works best is a 3-way fridge that can run on propane, 12V DC or 110/220V AC. I've used one for a decade now. An additional freezer chest makes sense for those who mostly live at the dock.

  18. Having spent a decade aboard my sloop, the good ship Discovery, in Astoria, Oregon; I discovered diesel heaters and most importantly, 12v fans.
    Kept a 30' sloop mold free and dry.
    Strategically placed fans keep the air moving from forepeak to stern.
    Fans, most important, when battened down for inclement weather; Astoria is notorious for forms of nasty weather.

    1. Why do you favor diesel over other fuels?

    2. Because most boats are diesel powered. Thus, a diesel heater uses fuel from an already installed tank.
      And its universally available; world wide.
      Propane is problematic for a number of reasons; primary of which; it settles in low spaces when leaked.

    3. I mean, is there some other benefit for using diesel as a primary heating fuel? Quidnon is not designed to use diesel at all, so I was wondering if you had noticed any other virtues.

    4. Diesel is stinky and it can make lots of soot and CO from incomplete combustion. There won't be any diesel on QUIDNON, so no diesel heater. Propane works well, in my experience. What works even better, though, is charcoal. But some marinas don't allow solid fuel. In terms of safety and convenience, propane is best. Electric heat is even more convenient, but expensive.

    5. I once saw a plan for a homemade charcoal heater, that used a stack of commercial briquettes and auto-fed by gravity. Supposedly ran fairly constant for several hours on a stack of 8 briquettes. I never tried it, myself. It was light enough to hang by it's own chimney pipe. I believe that I saw it bundled with my Triloboats plans, if I recall correctly.

  19. If you had one of these on your Quidnon... could wash a small load of clothes, but then where would you dry them? On a calm, sunny day, just hang them out under the deck arches. But what if it's rough or raining? Since we are building heated, vented space under the sole, I wonder if a small closet with a vent on the floor could be used as a drying closet space. Or maybe just hang them from hooks on the ceiling.

    I note that since this product is basically just a small tumbling mixing bucket, it could be used for other things.

    1. What works best when overwintering aboard is using commercial washers and driers in the marina laundry room. What works best when sailing (during sailing season) is sailing naked.

    2. Well, that might be true. But I was looking for something that would work *without* electricity.

  20. We have a wee wood stove on our 35' sloop, and insulated with closed-cell foam. We could do with some fans. But it's amazing how little wood is needed to keep us toasty warm - just a little Japanese pruning saw to cut standing dead wood is all we use when we are away from our woodpile, but you could easily use scraps from a lumberyard if you're in an urban type place.

  21. Hello Dmitry,
    I understand that the QUIDNON will be a work in progress until the design has been finalized, so there are naturally some changes that have been and will be made. But reading previous posts that seem to disagree with recent posts confuses me a bit. Or maybe I have just misunderstood you and could use some clarification.
    For example, in the post "Creature Comforts," you wrote "On QUIDNON, I plan to address these problems as follows. *The inside of the hull will not be insulated at all.* Instead, there will be an air gap between the hull and the walls of the cabin, which will be made of an additional layer of plywood mounted over fir ribs. It is the outside of the inner walls that will be insulated with ¾-inch pink foam insulation and radiant barrier. The function of the air gap will be to thermally isolate the cabin from the hull, and to allow condensation to form freely on the hull, drain to the bilge, and be pumped overboard by the bilge pump."
    However, above you wrote "The easiest procedure for installing the radiant barrier, which is essentially bubble wrap that incorporates aluminum foil layers, is *directly onto the hull* surfaces using double-stick mounting tape. The slabs of foam insulation can then be cut exactly to size and press-fit into place with a bead of expanding foam all around, for a tight seal. The foam can then be covered with thin (1/8-inch) plywood sheets."
    Do you still intend to leave an air gap between the hull and the cabin or will the radiant barrier be placed directly onto the hull with foam insulation over it?
    Please advise.

    1. It is important to provide a drainage path leading to the bilge for condensation that will inevitably form between the hull and the insulation. Probably the easiest way to do it is by inserting a layer of corrugated plastic with vertical corrugations. Probably the best combination, from the outside in, is the corrugated plastic against the inside of the hull with limbers below it leading down to the bilge, then a layer of radiant barrier. These can be installed using small tabs of double-stick tape. Finally, a layer of closed-cell foam (the pink stuff works best) is press-fit into place. It's available in 2 thicknesses (.75" and 1.5", in 2x8' sheets, if I recall) and fit together tongue-in-groove.


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