There are many reasons for unpleasant odours on board. Due to the usually quite high humidity, musty odours from mattresses or poorly ventilated wardrobes can hardly be prevented. If plastic or fuel vapours and toilet odours from non-gas-tight waste water hoses are added to this, the result is an inimitable mix that quickly spoils a multi-day stay on board, and not just for sensitive ladies' noses. The motto "ventilate, ventilate, ventilate" is well-intentioned, but is rarely actually realised in practice. Who wants to leave their boat with open hatches, windows or doors for days or weeks on end in our latitudes? And room air fresheners, fabric sprays or "miracle trees" are no solution either. In most cases, they only mask the unpleasant odours with additional fragrances, which ultimately leads to complete sensory overload and even headaches.
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For some time now, so-called ozone generators, such as those used by professional car valeters, have promised a genuine and, above all, sustainable solution to the musty smell problem. In contrast to room sprays or other chemical odour sources, these devices actively combat unpleasant odours by largely eliminating their causes.
The mode of operation
An electrical high-voltage discharge within the ozone generator breaks down the oxygen molecules contained in the room air, forming ozone - also known as "active oxygen". In nature, this process takes place during a thunderstorm, for example, and is perceived by many people as "fresh thunderstorm air". The resulting gas is then distributed throughout the room to be treated by an integrated fan and reaches every hidden corner.
However, as ozone is chemically unstable under normal conditions, it decomposes back into its components. In the process, free oxygen atoms attach themselves to the molecules of organic compounds and lead to oxidation and thus ultimately to disinfection. Hydrocarbons, hydrogen sulphide, mould spores and even germs decompose within a very short time and can therefore no longer cause odours. Ozone generators achieve the best effect at low humidity levels (below 50 %) and temperatures of more than 20 degrees Celsius. A clear and warm summer's day is therefore the ideal time for this type of "cleaning". A complete ozone treatment of a boat cabin measuring approximately 3 x 3 x 2 metres takes around one to two hours.
But beware: we humans are also made up of organic compounds! In plain language: While the ozone generator is in operation, no people, animals or plants should be in the room. And even after the appliance has been switched off automatically by a timer, you should wait at least three quarters of an hour before entering the room. The room must then be thoroughly ventilated.
The lung doctors at the German Lung Foundation (DLS) in Hanover have issued additional safety advice on the use of ozone generators: according to them, ozone generators should not be used to clean rooms that are heavily contaminated with nicotine. According to a US study, ozone breaks down nicotine residues into so-called aerosols, which in turn narrow the airways and can trigger asthma. Ozone treatment could therefore achieve the opposite of the desired effect.
The practical application
To test the effect of such an odour killer on the boat, we bought a commercially available generator with an output of around 3.5 grams of ozone per hour. Depending on the supplier, this costs between 150 and 300 euros. If you don't want to buy your own generator, you can also find suitable hire offers or even a complete cleaning service including ozone treatment. If you believe the manufacturers, devices with an output of 3.5 to 7 grams per hour are completely sufficient for medium-sized rooms, vehicles and boats. The integrated timer allows operation in ten-minute increments up to a maximum of two hours, which is also sufficient for our purposes.
Incidentally, ozone generators should not be confused with so-called air scrubbers or room air filters. The technology described here does not use any filters, so dust contamination is not removed. For this reason, thorough cleaning of the surfaces with conventional cleaning agents (disinfectants) is recommended in parallel with ozone treatment.
Commissioning of ozone generators
Setting up and operating the 230 V device is very simple, and after closing all the hatches and doors in our 40-year-old cabin cruiser, we left the ozone generator running for an hour. After the automatic switch-off, we waited a further hour before entering the cabin to open all the hatches and doors again. We noticed a slight odour of chlorine, as you would expect from a swimming pool. However, after thoroughly airing out the entire boat, we could no longer detect any unpleasant odours. To put it plainly: the ozone generator had done a great job, the odour and mustiness of the past four decades had been blown away. According to the appliance manufacturers, a standard ozone generator lasts for around 5,000 operating hours, which equates to 4,000 to 5,000 uses on a boat. After that, the high-voltage element in the device is used up and has to be replaced - a job for an electrician due to the high-voltage parts.
Whether and to what extent the unpleasant odours will return after a certain period of time cannot be conclusively assessed at the present time (three weeks after application). We will report on this at the end of the season.
