It's a nasty thing: you've polished and cleaned your boat in winter storage, but as soon as it's out of the shed, a nasty reddish-brown layer of dust settles on everything. On the deck, fittings, rigging, sailcloth and sprayhood. The many hours of loving winter labour seem to be for nothing. In addition to the purely visual annoyance, this dust can also cause damage to the boat, from scratches to increased wear and tear, if it is not removed properly. This phenomenon is usually caused by Sahara dust. Owners in southern climes, such as the coasts of Croatia, Italy, France or Spain, are familiar with it. However, it also occurs from time to time in the north.
How Saharan dust gets on the boat
Sandstorms frequently occur in the Sahara, whirling large quantities of dust and sand into the atmosphere. These particles can reach the higher layers of the atmosphere, where they are caught by the prevailing winds. The winds transport these particles over long distances, usually with the trade winds across the Atlantic, where the dust is an important fertiliser in the Caribbean and South America. In southerly winds, however, it can reach as far as Europe and Germany.
In the Mediterranean regions, this is usually the case with southerly winds such as the Scirocco/Jugo. As these are often associated with rainy weather, the rain washes the dust particles out of the atmosphere, leaving a reddish-brown rain slush on the ground, also known as blood rain, or blood snow in winter. The dust rarely reaches the Baltic Sea region or further north, but up to 20 such events can occur per year. It is then usually transported over the Alps by foehn winds.
What Saharan dust does to boats
Saharan dust itself poses no greater danger than other dusts. However, the particles are very fine, almost flour-like. This is why they remain in the air for a long time and can penetrate into almost every nook and cranny on board. While the dust on deck is only primarily a nuisance, the situation is different in other places. In blocks or winches, for example, it acts like a fine abrasive and can lead to increased wear and sluggishness.
It also likes to get into ropes, which means that sheets or halyards can suddenly turn into something like emery cloth. While they previously ran cleanly over bulges, they can suddenly eat into the gelcoat at such points.
Even electronics can be damaged if the fine particles get into the housing of the displays.
If the dust gets wet, either because it is washed out of the atmosphere by rain or because it rains after settling on deck, accumulations of the dust can form in deeper places and indentations on deck. When these dry, they form a hard crust.
How to remove Sahara dust
Sweeping:
If there is a lot of dust on deck, you can first try to remove the worst of it with a soft broom. But be careful: any mechanical cleaning can lead to an abrasive effect, as you are moving very fine sand particles over surfaces. Particular care should be taken with the plastic panes of sprayhoods.
Wipe:
The dust can also be easily wiped off with a damp cloth. However, very soft cloths or sponges should be used to avoid an abrasive effect.
Rinse off:
The best way to tackle Sahara dust is with water. A powerful jet from the hose usually removes a lot of dust. The deck and fittings can then be rinsed again with water to which a light, environmentally friendly detergent has been added.
Stubborn dirt can also be tackled with a high-pressure cleaner, but at very low pressure and at a great distance so as not to damage the surfaces of the boat.
Rinse with salt water:
If there is not enough fresh water available at the mooring, as is the case in many Mediterranean regions, especially in the high season, or if you do not want to use fresh water unnecessarily for the sake of the environment, salt water will have to suffice. The same applies to rinsing as with fresh water. It can normally be used to wash the Sahara dust from the deck and fittings. However, you should rinse with fresh water at the very end if it is not enough for the whole boat, at least rinse the fittings. Otherwise, salt crystals can form after the water evaporates, which can lead to increased wear and sluggishness, especially in mechanical components.
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Effective protection against Saharan dust
Only a boat hall would offer complete protection against Sahara dust. However, partial protection can be achieved with a few measures:
- Use tarpaulins: With a sail dress over the genoa and mainsail, you normally protect them quite effectively against the Sahara dust. However, sailing clothes are particularly advisable as UV protection. Coverings for the winches, for example, can also protect them. This protection is also effective as a complete or partial tarpaulin for the boat or just the cockpit. The closer the tarpaulin is to the deck and hull, the better.
- Protection of the electronics: Sahara dust can penetrate electronic devices and damage them. Ensure that all electronic devices are well protected, the easiest way to do this is to fit the covers.
- Check ventilation openings: To prevent Saharan dust from finding a way below deck, make sure that the ventilation openings, such as hatches or forced ventilation, remain largely closed during days with Saharan dust exposure.
- Protect ropes: Take off sheets and all unnecessary lines and stow them in the forecastle or below deck to protect them from dust.
Lars Bolle
Chief Editor Digital
