Damp and condensation can lead to serious problems in a yacht, getting hold of the best boat dehumidifier will make an enormous difference. David Harding looks at 10 of the best options on the market
It sounds obvious, but boats tend to live in a damp environment. Even if you keep yours ashore or in your driveway, damp can still present a problem – just as in a car or caravan. So buying the best boat dehumidifier for your needs is important.
An added challenge with boats is that that salt water inevitably finds its way down below. And salt, as we all know, retains moisture.
Since iron will start to rust when the relative humidity exceeds 50% (80% for steel), the problems caused by damp aren’t limited to mould, mildew and mustiness: electronics, electrics and engines will suffer too, not to mention tools. This is where a good boat dehumidifier can help.
This is one of the lightest, simplest and least expensive desiccant dehumidifiers on the market. Despite its relatively low price, it does a lot more than the old basic ‘on/off’ compressor types that some of us have been using for years.
One useful feature is a humidity dial, which allows you to set the level at which it turns itself off to save power. When power-saving is less important than drying a particularly damp space or directing the heat to help dry clothes, you can leave it on the ‘laundry’ setting for short periods. There’s also a two-speed fan, and a nano-silver anti-bacterial filter to help clean the air.
Weighing a modest 6kg (13lb), the DD1 Simple has a carrying handle on the top and is claimed to extract 7 litres of water a day at 20°C and 60% relative humidity.
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Some manufacturers have traditionally concentrated on compressor dehumidifiers, which have a reputation for lasting longer than desiccant types as well as for using less power. This means that people tend to be happier to leave them on for longer, while the nature of their noise is often considered to be less intrusive even if the actual decibel count is no lower.
De Longhi’s DEX214F sit in the middle of their range, with an extraction rating of 14 litres of water per day (given the standard test conditions of 30°C and 80% relative humidity, which are rarely seen on a boat in a high-latitude winter).
Buyers with environmental concerns about refrigerant gases will be reassured to know that DeLonghi use R290 gas, which is claimed to be much more environmentally friendly than the gases traditionally used in refrigeration appliances.
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Made in the UK, this popular desiccant model from Meaco has proved popular among boat owners because of its light weight (6kg/13lb), low noise and efficiency at low temperatures.
Claimed to extract 7.5 litres of water per day at 20°C and 60% relative humidity (equivalent to higher-capacity compressor dehumidifiers, which are tested at higher temperatures and humidities), it has two fan speeds, a variable humidistat and a laundry mode for maximum extraction or for drying clothes.
It’s also claimed to be particularly economical to run because of the way that it regularly samples the humidity and runs for the minimum time necessary to maintain the chosen level.
If you want an ioniser and an anti-bacterial filter, you can spend a little more and buy the DD8L model as opposed to the DD8L Junior.
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This is by no means a budget dehumidifier, but that’s not what Mitsubishi designed it to be. Although it uses a compressor rather than desiccant, it has a low-temperature function that’s said to keep it working efficiently in cold weather.
Compressor dehumidifiers have to stop working at intervals when the temperature drops and moisture freezes on the cold plates of the heat exchanger, but the Mitsubishi has a hot-gas defrosting system to help offset this generic drawback.
In warmer, humid conditions (the standard 30°C and 80% humidity at which dehumidifiers are rated) it has a capacity of 16l per day.
A variable humidistat is among the other features, together with a laundry function, on/off timer and deodorising filter.
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If you want a seriously heavy-duty dehumidifier that’s made of stainless steel to withstand the marine environment and that can be left unattended and running 24 hours a day, one of the Ecor Pro desiccant models is likely to attract your attention.
Designed in the UK, the DH1200 Inox will extract up to 12l per day and can be free-standing or attached to a horizontal surface or a bulkhead. It has no water bucket because the moisture is vented out through a duct that will accept standard 41mm waste pipe. You can also attach an inlet pipe to suck in moist air from elsewhere.
Operating temperatures range from -20 to +40°C and this boat dehumidifier has been engineered for ease of access when maintenance is needed.
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Seago’s Ecodry is one of the small number of dehumidifiers to be designed with boat owners very much in mind. You should be able to leave it running continually and, being of the desiccant type, it will keep working (collecting up to 7l a day) at temperatures down to 1°C.
Features include a digital display on the top, where you set the mode (choices include ‘sleep’ for lower noise and a dimmed display) and where the temperature and humidity are shown.
Carrying handles are recessed into the sides. While that’s arguably neater than having a fold-down handle on the top, you won’t be able to attach a line to haul it up if you’re on deck with the boat ashore. Then again, being one of the lighter and more compact boat dehumidifiers (it weighs 6kg/13lb and is less than 500mm/20in high), it’s less of a lump than some to carry up a ladder.
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Ebac is a British manufacturer with a different take on what a dehumidifier needs to do and the best way to do it.
Rather than trumpeting the benefits of desiccant dehumidifiers and humidistats that allow you to choose the humidity level you want, Ebac presents an argument in favour of the compressor combined with their own patented Smart Control feature.
Compressors are used for their appreciably lower running costs – up to 40% lower, it’s claimed – while the Smart Control is said to detect changes in temperature and moisture levels, switching the dehumidifier on and off as needed.
Ebac’s premise is that there is no consistently ‘right’ level of humidity for any given environment: it varies continually, and the 3850e responds by extracting only as much moisture as is needed to avoid damp and condensation rather than making the space unnecessarily dry and sucking in more damp from outside.
It also incorporates a defrosting system that minimises the time when it’s out of action.
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PBO tested: Meaco DD8L Zambezi review
If you like the Meaco approach but want something with a few more bells and whistles than the basic DD8L models, the Zambezi (named after an orphaned elephant in Zambia) might be the answer.
It’s a desiccant machine with a maximum extraction of 8.3l per day (at 20°C) and should still extract 7.5l at 10° and 60% humidity. Power consumption at 20° is 351W and the tank capacity is a larger-than-average 3l.
Features that make it more expensive than Meaco’s other models include the sterilising ioniser and a low-energy laundry setting. It also has full timing functions, which allow you to set when it comes on and when it goes off.
Like most manufacturers, EcoAir offers models to suit a range of budgets and the Mk II version of their popular DD3 Classic dehumidifier comes with more features than you find on the lower-priced alternatives. As well as auto-restart after a power interruption and a laundry mode – both widely found elsewhere – this one incorporates multiple timer settings and an antibacterial nano-silver filter. It’s said to be quieter than its predecessor, producing 36dB on its lower setting.
Being a larger unit, with an extraction rate of up to 10.5l per day, it uses a little more power: consumption ranges from 420-735W. With a capacity of 4.2l, the tank is bigger too. It’s 520mm (20in) high and weighs 7.5kg (16.5lb).
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ProBreeze makes both desiccant and compressor dehumidifiers as well as smaller models that use Peltier (thermo-electric) technology to create a cold plate on which moisture condenses.
If you heat your boat in the winter, you might find that a compressor dehumidifier makes most sense; otherwise opinions in colder climes tend to shift in favour of desiccant types and ProBreeze’s 10L (which stands for 10l of extraction per day) is the company’s offering in this department.
It offers a humidity sensor so you can set your chosen level, a digital control panel, a timer, a fold-down handle on the top, an adjustable outlet for the warm air, a nano-silver filter and a 3l collection tank.
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Mechanical dehumidifiers that run from a mains supply are often left on the galley worktop to drain into the sink so they don’t cut out when the water bucket fills up. That’s unless you have a top-of-the range boat dehumidifier that’s ‘plumbed in’ and expels water to the outside.
Your first choice is likely to be whether to buy a condenser type of boat dehumidifier or one of the newer desiccant types. The former use a compressor and refrigerant gas to create cold plates or coils on which moisture in the air, drawn in by a fan, condenses before dripping into a bucket.
With the desiccant dehumidifiers, the air passes over a rotating wheel coated with an absorbent material (typically zeolite). The saturated wheel is dried by hot air that’s then cooled so, again, the condensed moisture is collected. This process is more power-hungry, but desiccant dehumidifiers are typically lighter. They also heat the surrounding air and work better at lower temperatures, when condenser types have to shut down periodically to defrost.
Whichever you buy, bear in mind that not all domestic dehumidifiers are designed to be left running for lengthy periods. There have been instances of fires on board being attributed to boat dehumidifiers, so it’s a good idea to check with your insurers just to make sure.
Read PBO’s group test of boat dehumidifiers
Didn’t find what you’re looking for? Head to Amazon’s dedicated boating page for more marine products.
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