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.