1. Damp Bed
Problem:
If you have ever taken the upholstery off your mattress you may have noticed a strong mildew odour and some discoloration on the underside. Another sign that all is not well in the bedroom is the feeling of getting into a clammy, perceptibly damp bed. It is hard to stay warm when your sheets and bedding are moist.
Cause:
There are a couple of reasons why moisture is collecting in our nocturnal abodes. The first and most common cause is that the mattress hasn’t had the chance to dry out from the previous night. Our bodies are always releasing moisture—it’s how we regulate body temperature—dripping sweat being an extreme example. Over an entire night we release a lot of moisture all around us. That moisture travels through the bed mattress relatively easily, but when it comes to the cold plywood, or fibreglass on which our mattress rests, it cannot go any further and there it condenses. The other reason is that bedclothes are most often made from cotton, which is a hygroscopic material (see sidebar).
Solution:
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- Prop up the bed during the day to allow the mattress to dry out.
- Drill one-inch holes in a six-inch by six-inch grid pattern in the plywood under your bed, allowing the moisture released during the night to pass through into the space under the bed.
- Install a mattress underlay, like Hypervent or something similar that provides for air circulation under the mattress. The underlay must be open on the sides, otherwise air will not be able to circulate effectively to remove the moisture.
- Ensure your mattress and bedclothes are made of polyester or a similar hydrophobic material.
2. Moldy Clothes
Problem:
Similar to the mattress and bedding, and for the same reasons, when left sitting, clothing often takes on a disagreeable odour and can be unpleasant to put on.
Cause:
The main cause of damp, smelly clothes is that clothing is often kept in confined spaces close to the hull of the boat. The hull of the boat is in contact with seawater, which is almost always cooler than the interior air temperature of the boat. When moist air comes in contact with cool surfaces, it too begins to cool. As it cools, the humidity rises. If it cools enough, to below the dew point, the excess water condenses on the nearest surface. Whether the water vapour condenses or not, the high humidity levels in the cooler air are perfect conditions for mold growth. Additionally, most of our clothes are made of cotton and thus attract water.
Solution:
- Move the clothes from being in contact or very close to the cool interior surface of the hull. Don’t pack clothes up tightly to the hull if there is another place you can keep them.
- If the clothes cannot be moved, say in a closet or set of drawers, you can install a golden rod. A golden rod does not dry out the air, but rather keeps the air temperature in its local vicinity high enough that high humidity levels don’t develop. An alternative to a golden rod is a light bulb, or some other device that provides some localized heat to the area, but be careful of fire hazards.
- Keep a desiccant in with the clothes. A Dri-Z-Air container with desiccant crystals will remove moisture in its local vicinity. It must be emptied and the crystals regularly replaced to ensure optimal function. Silica packets (available from most clothing stores for free) can also help keep moisture levels in a drawer at a manageable level.
- Wash clothes before storing them. Salt attracts moisture out of the air (see below), so if there is salt on the clothing, they will quickly become damp. If left for a long period of time, that dampness creates the right condition for mold growth.
3. Salt Shaker Clumping
Problem:
Salt, flour and spices have a tendency to clump quickly on a boat, making it difficult, if not impossible, to dispense them. In many cases there is liquid water on top of the salt shaker.
Cause:
Common table salt (Sodium Chloride) is extremely hygroscopic and attracts water molecules from the surrounding air, binding them to itself. Most natural materials are hygroscopic, including foodstuffs like flour, crackers, bread, rice, sugar and spices. These are fairly common provisions on a boat so keeping them dry and usable is important.
Solution:
- Keep food in completely air tight, or relatively air tight containers to prevent high humidity in the immediate vicinity of the food.
- Add a desiccant pack to the bag or box of food. You will often see silica desiccant packs in bags of potato chips. That’s to keep them crisp in the bag, not to keep them from going bad. Desiccants can be toxic so ensure you read the directions before using.
- Add rice to the saltshaker or other spices. Adding rice, which is also an extremely hygroscopic material, to the salt, sugar or other spices, will help remove moisture. The rice attracts water more readily than the surrounding food and also helps to break up clumps in the powder.
4. Water in the Diesel Tanks
Problem:
Water in the diesel tanks.
Cause:
One wouldn’t think of diesel as something that attracts water, but it actually attracts water very well. It is diesel’s hygroscopic property that requires a diesel/water separator before the fuel gets to the engine injectors. Diesel tanks usually have vents to the outside to allow expansion and contraction of the air in the tank. However, this free flow of air allows high-humidity air to come into contact with the fuel in the tank. The diesel attracts the water molecules out of the air, which can lead to high water levels in the diesel and the development of microbial growth. Microbes can only live in diesel if there is water present and, once they are established, secrete acids that wreck diesel quality, corrode tanks and lead to fuel filter and injector clogging.
Solution:
- Keep the diesel tanks full. The more diesel that is in the tank the less moist air will be in the tank. Additionally, the relatively cooler sides of the partially empty diesel tank allow water to condense out of the air and run down into the diesel itself.
- Add diesel fuel additives with an emulsifier to the fuel tank every time you fill it. The emulsifier bonds the water molecules to the diesel molecules and traps it so it can safely pass through injectors and be incinerated in the combustion chamber. You’ll sometimes notice a whitish smoke, or steam, coming from the exhaust. It is usually liquid water being turned to vapour in the combustion chamber as a result of the emulsifier in the fuel additive.
- Frequently check the functioning of your water/fuel separator and clean out the catchment bowl regularly.
5. Wet Sole Panels (Floorboards)
Problem:
Cool or damp sole panels that begin to degrade the finish and in many cases rot out the wood. If your floor is fibreglass, water will pool and soak through carpets.
Cause:
To have a dry bilge is an unattainable luxury for most boat owners. Constant water in the bilge ensures that its immediate surroundings will be at a very high humidity (close to 100 percent). The sides of the bilge and the undersides of the sole panels (floorboards) are the surfaces in direct contact with this humidity and are the most affected.
Solution:
- Frequently pump out the bilge. The less water in the bilge the more air there is to absorb the moisture thereby reducing humidity levels.
- Keep air circulating through the bilge. Many boats are equipped with bilge blowers or breeze-ways that keep air moving through the bilge. The air can be taken from the exterior or the interior of the boat, but should be exhausted to the exterior. If you do not have a dedicated breeze-way or blower, you can install a small fan in the bilge to at least keep air moving.
6. General High Humidity
High interior humidity levels and mold growth.
Cause:
Boats are more susceptible to high humidity levels simply due to their proximity to water. The closer one gets to a body of water, the higher the humidity in the surrounding air will be. With some attention, the interior of your boat can be kept at reasonable levels that are less than 60 percent relative humidity.
Certain times of the year are worse than others. Spring and fall often bring moderate temperatures and high humidity levels that are perfect for causing difficulties in the interior conditions of a boat. Winter can also be a difficult time, especially for liveaboards. Lowering overall humidity levels will also help manage moisture levels in problem areas like those discussed above and should be the first step in any moisture management strategy.
Solution:
- Seal locations that allow air to leak in or out. Managing the air in the boat’s interior begins with controlling its movement. A common issue is the companionway door or hatch not sealing off the interior. Adding foam weather stripping can provide an adequate air seal. The same can be said for any hatches, windows or doors that are not well sealed.
- Install a hygrometer. A hygrometer is a device that measures the temperature and relative humidity of the location in which it is installed. They can be purchased at a hardware store for as little as four dollars, though I would suggest buying one in the $20 range. A boat interior is relatively small and open so one hygrometer should be adequate if it is installed in an open location.
- Install a dehumidifier. We had a dehumidifier while living aboard our boat and it made a huge difference. We kept the interior humidity around 60 percent by dehumidifying 30 pints of water per day during the fall. Due to the high moisture load in the small enclosed space I would suggest getting a dehumidifier that is greatly overrated for the square footage of your boat.
- Pay attention to the outdoor humidity. Most weather forecasts will list humidity levels for each day. On days of low humidity (less than 55 percent) open the boat up to allow the outdoor air to remove trapped moisture. On days of high humidity (greater than 60 percent) keep hatches and windows closed to prevent outdoor air from freely entering the interior.
- Keep the interior of the boat warm. As we discussed above, high temperature air take on more water. This will keep interior humidity levels relatively low and ensure that any air leakage from the exterior will not significantly raise humidity levels. A small Caframo space heater with a thermostat may be substantial enough.
Boats don’t have to be cold, damp places. Understanding why the bed smells, clothes are clammy or the saltshaker clumps is the first step in identifying the right solutions. In most cases the solutions are quick, easy and cost effective.