Boat owners that have to endure a Northern hemisphere winter on the hard or time stored in the tropics will know the apoplexy inducing carnage that is mold and mildew. You'll be needing a boat-load of the best non-electric dehumidifiers and be stashing them in every cupboard, nook and cranny. The cost of these non-electric moisture absorbers has to be weighed up with the high cost of damage that unfettered mold will cause to upholstery and any other porous material you keep onboard. They're worth it. But with so many cheap versions available, how do you know if it'll actually do the job? Here's some of the best non-electric dehumidifiers that we at have used on our own boats and keep using over and over again.

Humidity is the bane of a boaters life, it will get into your life jackets, into your foulies, into the furnishing, the untreated wood, into the curtains and anything else vaguely porous. The most efficient way to deal with tropical humidity or winter condensation involves: electric heating, fans, or air conditioning. But, mains power is not always available, especially on hard standing in a tightly packed yard. You’ll be needing other moisture sucking methods that go off-grid, and that generally involves calcium chloride salts, crystals or silica gel in the shape of several non-electric dehumidifiers dotted throughout your boat.

hanging non-electric dehumidifier and moisture absorber with life jackets

Don’t let mold or mildew damage lifejackets – use a moisture absorber | Best non-electric dehumidifiers |

I’ve had lifejackets self inflate in the cupboard because of humidity. Zips have gone furry and refuse to move on the binocular case. My best hiking sandals were given a ceremonial send off after they too succumbed to the mildew and were ruined. And that time I opened the door to the back cabin after after a week of being closed, to be greeted with an entire new  eco system of black mold covering the side lining; well I still have flash backs to this day.  The price of not using some sort of dehumidifier can be very costly.

Just because we’re using a consumable item doesn’t mean we can’t be eco conscious though. We’ve given our best non-electric dehumidifier and moisture absorbers buyers guide an eco rating, which relates to the ease with which these can be re-used or recycled after use.

damprid moisture absorber and non-electric dehumidifier

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DampRid moisture absorber tub

‘DampRid’ is the major name brand in the USA for various forms of moisture absorbing non-electric dehumidifiers using calcium chloride crystals.
The crystals, which are a form of salt, attract water, they dissolve and the storage container is filled with a water and salty mix which can be poured away down a standard drain. The containers may be refilled with new crystals (sold separately in refill packs)

Large containers like this one are great for open spaces, such as a main cabin or saloon where they can be sat on a flat surface, like a saloon table or galley counter. Beware of balancing them on cushions though as they could tip and spill on an uneven surface.

These Damprid  tubs are refillable with a range of proprietary salts and crystals and the containers are made from recyclable plastic.

Pros: very easy to use, it’s possible to use non branded crystals in this tub

Cons: quite an ugly looking unit, small tub is not sealed and can tip or be spilled

Eco rating 5/5
User rating 4/5

Price: $18.19

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Damprid hanging moisture absorber

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DampRid hanging moisture absorber

DampRid optimized for hanging lockers, closets, heads, and other enclosed spaces. One of these hanging bags of DampRid will last about 2-3 weeks in a tropical climate when used in a hanging locker. I personally prefer the hanging variety even for larger areas like a main saloon because it is less likely to spill. I have three or four of them hanging from main saloon handholds while storing a 38’ sailboat in the blistering and sticky Florida Keys for a couple of months during summer to great effect. This was however, on a boat with dorade vents and no leaks that was in fairly pristine condition as far as 30-year-old sailboats go.

Pros: spill proof, easy to hang, easy to see fill rate

Cons: single use, can’t be refilled, hard to recycle

Eco rating 1/5
User rating 5/5

Price $19.99

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hanging scented wardrobe dehumidifier

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Hanging Scented wardrobe dehumidifier

These hanging dehumidifiers, available in the UK are the same as the DampRid above, but with an additional lavender scent. Functionally, they do exactly the same. They are a clear plastic bag in two sections with the calcium chloride crystals in the top. These gradually dissolve into the sealed hanging bag below. They can be disassembled to recycle the hanger and the plastic bag can be cut away from the paper absorption part, but it’s tricky and recycling this disposable moisture absorber is not easy. They are a really good method of sucking moisture out of hanging lockers though.

Pros: spill proof, easy to hang, easy to see fill rate

Cons: single use, can’t be refilled, hard to recycle

Eco rating 1/5
User rating 5/5

Price £4.79

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UniBond Aero 360 non-electric dehumidifier

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Unibond Aero 360 dehumidifier

This a popular and more stylish model of passive dehumidifier. The same style unit can be found under different manufacturer names but Unibond is the one found in the UK.
The unit is tall and slim. The Aero 360 is designed to be refilled using a hard circular puck sized tablet of Calcium Chloride. The top housing and liquid container clip together and to empty, you pull out a small pouring bung to tip the liquid away. It isn’t a sealed unit though and should be protected from being knocked over to avoid spills. Best used on a non-marking flat surface in a larger cabin or saloon.

There’s very little waste on these, the container will live for years. My current unit is 9 years old and still going strong. The refills come in a plastic sealed pouch that is recyclable.
A good Eco option.

Pros: good capacity moisture container, easy to see water level, sturdy refillable design

Cons: not a sealed unit so can be spilled, the pouring bung can be a bit messy

Eco rating 5/5
User rating 4/5

Price from £8

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Acana gel safe moisture trap and non-electric dehumidifier

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Acana Moisture Trap

Editors's choice five stars badge

These are perhaps the best of all of the passive non-electric dehumidifiers listed above because this unit, unlike all of the others, is both reusable and spill-proof because it is ‘gel safe’. The unit uses pouches that start off feeling gritty and slowly turn to squishy gel when they’re spent.

These are optimal for both tight spots, as well as places where they are likely to be knocked over. They are non-marking and can fit into some really tight spaces. Also highly recommended for high-traffic areas.

Pros: very clean to use, no spill gel safe design, refillable

Cons: the gel safe pouches are difficult to recycle. 

Eco rating 4/5
User rating 5/5

Price £7.99

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divchi non-electric dehumidifiers

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Divchi Moisture absorber

These handy little containers are easy to stow under your bathroom sink when in storage before use and can be tucked into some of the tightest spaces when activated. There is a barrier seal on the top that allows damp air to enter but it helps to stop spills if these are knocked over. Best used in conjunction with other non-electric dehumidifiers, these are a bulk order, just-in-case sort of moisture absorber.  I usually keep a few spares for problem cupboards as and when they arise. The drawback with these is that they aren’t refillable but the plastic is recyclable.

Pros: very handy small tub that can fit into tight spaces, easy to store before use

Cons: very easy to tip over, non-refillable design

Eco rating 2/5
User rating 4/5

Price £8.99

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unibond mini moisture absorber - best non-electric dehumidifiers

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UniBond Mini Moisture Absorber

These miniature moisture absorbers by Unibond,  (similar or identical units available under different manufacturer names including humdry in mainland Europe) are a great choice for small, enclosed compartments found onboard like the forepeak or galley cupboards. While they are spill resistant, when full they can easily make a mess while being transported to the sink. The small solid refill tablets come in two types, one with an additional scent such as apple,. citrus or lavender or plain unscented. There are a perfect companion to the other products on this buyers guide to non-electric dehumidifiers. They do work well in small cupboards, especially galley cupboards, such as those with cans that are prone to condensation and may help to keep rusty cans at bay.

Pros: compact unit, easy to refill, good variety of scents available

Cons: easy to spill, only work in very small spaces

Eco rating 5/5
User rating 4/5

Price from £6

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West Marine dehumidifier 120v dry air blower

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West Marine Air Dryer with Fan dehumidifier

This buyers guide focuses on methods for passive dehumidification, however this little AC unit is low powered enough that if you have a good solar array, then you may still be able to run this off-grid, so we decided to include it.  This isn’t a heater, so it’s safe to leave unattended. (check manufacturers guidelines for use) With a small footprint of approximately 25cm or 10 inches diameter it will fit easily within a cabin or saloon.

Pros: circulates a good volume of dried air, very low power consumption

Cons: requires 120V AC

Eco rating 4/5
User rating 4/5

Price $99.99

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What we look for in the best non-electric dehumidifiers

  • As these are either disposable or refillable, we’re looking for recyclable plastic or compostable materials.
  • We look for units that don’t spill their contents easily, with either a deep container or a stable base
  • Are refills easy to access and obtain?
  • Do they actually suck moisture out of the air?
  • They might have a nice fragrance to leave small spaces smelling fresh rather than stale.


If you want to read more about electric dehumidifiers you can read about them at

If you are looking for more information on winterising your boat, then read more at

Looking to stay warm on your boat all year round? Then read more at Yachting Monthly

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