Moisture board

Moisture board is inevitable; Jordi Maseras helps us understand what it is and how we can protect our boat from its worst effects.

Like it or not, our love develops in a very conducive environment for the phenomenon of moisture constantly appears, in addition to the effects it can have on our body manifesting as arthritis or rheumatism, can also bring problems of corrosion, rust and mildew on board our ship.

What is humidity?

Humidity is no more than the manifestation of evaporated water in the atmosphere and condenses temperature difference . Water plays an important role of thermal regulator in the atmosphere due to its strong thermal inertia (both its heating and cooling are slow). A mass of air can not exceed certain maximum gaseous water, exceeded this maximum water vapor becomes liquid causing condensation . Also, below a certain temperature, the condensation phenomenon is repeated, the colder, less water may contain gaseous air and vice versa, more heat can withstand water more gaseous air.

We all have seen what happens when in summer in a glass put a soda and add some ice cubes to keep our drink cooler. After a while, the outside of the glass is fogged and then a few drops of water, after some time form, create a puddle of water under the vessel. If instead of a glass, we use a plastic, see that condensation is much less and depending on the plastic used for the manufacture of the container, in certain cases become imperceptible. This phenomenon has an explanation is that the water vapor in the atmosphere dissolves to a limited extent since, as we have seen, the solution is a direct function of temperature. Although less important, the pressure also plays a role in this process, but in this case we do not take care of it.


One cubic meter of air at a temperature of 25C supports approximately 4,000 grams of water in solution, but if chilled air mass to reach 15ºC only support 2000 grams; or whether we 2,000 grams of water, dropwise, will leave the solution to be deposited on the colder surfaces of the boat, such as glass and metal parts. Depending on this temperature drop is more or less accentuated, these drops will fall and accumulate in the bilge they will slip .

Harmful effects

If drops of moisture / condensation fall on a surface in which there are traces of organic matter, such as fat example of our body on upholstery sofas or food debris uncleaned, it will become an ideal breeding ground for reproduction of microorganisms and consequently the appearance of mold .

As already mentioned, the moisture tends to condense on the metal parts because they are the first to be cooled. If we pay some attention to this, we can see that all our navigation instruments have these metal and more specifically in the electrical connections parts. If one were water which condenses, the phenomenon of moisture would have major consequences, but the air contains dust particles and minerals in suspension, to be dissolved by the condensed water can make a conductive bridge and after day, let the discharged battery if it is not in perfect condition and is not connected to an automatic battery charger.

How to fight moisture on board

Against mold exists above all a very effective measure: cleanup . Avoid above all food stains, traces of organic matter, breadcrumbs, etc.

Garments which remain on board, especially in winter, introduce in plastic bags, previously checking that are very dry, and inside plastic bags introduce a small cloth bags with salt silica or desiccator based compound hygroscopic material . If you do not have any of these matters at hand, a home remedy that usually works quite well is to fill the bags with salt, which absorbs moisture well.

In the bilge, plus the convenience of having an automatic bilge pump, we can install a “dry ball” which meet at a drug or, alternatively, a container with cooking salt, preferably cooking salt.
It is advisable to cover with Vaseline contacts navigational instruments , but never with silicone seal because any subsequent repair we would represent an additional problem. Petrolatum protects perfectly, even the parts that are directly in contact with water. Since the terminals are in close contact with the air, both outside and inside the boat, it is not advisable to use lubricant sprays, because eventually dry out and lose their effectiveness, the cheapest and cash is Vaseline . Silicone sprays exist, which are also a good solution because silicone is non – conductive and provides protection for more than six months to weathering, so inside can provide protection much higher.

It will also be essential to have good ventilation , because the circulating air greatly facilitates drying inside. If you do not have the ability to ventilate the interior regularly, especially in winter, it is advisable to have connected a portable dehumidifier to keep us dry boat and optimum moisture level. Exist in the market portable dehumidifiers are specially designed for enclosed spaces, in addition to removing moisture from carpets, cabinets and mattresses, also they contribute to odors disappear.

Normally they operate with relative humidity levels of between 5% and 100%, operating at 220V, have deposit several liters to collect water and all are provided with automatic stop when the tank is full. Also they are provided with an outlet tube for connecting an external drain.

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