Should Moisture absorbers be used in trailer for winter storage?

[Deane Williams]

Anyone have experience with using something like DampRid in a glider trailer to prevent condensation inside the glider during the cold of winter? Is there any downside to leaving it in for months? Thanks.

[Warwick Patterson]

I use them in my trailer, RV, airplane, etc. I also use the little stor-dry heaters (small UFO shaped fans with a small heater element). The little self-contained plastic moisture containers fill up fairly quickly in damp places, so you might need to check them periodically and replace. In my Maule I use a small/medium rubbermaid container with a small rack and I buy the Moisture Magnet refills and just place them on the rack. Its amazing how much water is sucked out of the air.

[Deane Williams]

Are you in a humid area or colder area?  What state?

[Warwick Patterson]

I’m on Vancouver Island on the west coast of Canada. Rains a lot, very damp, but we only get one or two snowfalls a year. Trailers are inside a fabric hangar so the coldest they get would be around freezing at the worst of times. 

Warwick Patterson

Vancouver Island Soaring Centre Ltd.

Port Alberni, BC

+1(250)-730-7627

www.gogliding.ca

On Oct 30, 2025, at 16:18, Deane Williams <pyroa...@sbcglobal.net> wrote:

Are you in a humid area or colder area?  What state?

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[Craig Funston]

If you can get power to the trailers a modestly sized dehumidifier works wonders. Hook up a hose to the outlet that empties through a small hole in the trailer floor. I’ve used this method for many seasons in Bellingham with a trailer that’s not under a tent. . The airflow plus humidity reduction keeps the glider and metal parts happy. 

On Oct 30, 2025, at 4:35 PM, Warwick Patterson <in...@gogliding.ca> wrote:

I’m on Vancouver Island on the west coast of Canada. Rains a lot, very damp, but we only get one or two snowfalls a year. Trailers are inside a fabric hangar so the coldest they get would be around freezing at the worst of times. 

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[Uli N]

I used the large-size DampRid buckets inside the cockpit and the trailer. Four in the cockpit (it's a large two-seater), two in the rear and two in the front of the Cobra-trailer. I was always amazed how much water they would collect in any season but particularly in the summer months, when the air in the Carolinas has 'texture'.

Uli

'AS'

[Uli N]

Forgot to mention: many years ago, a club member who had his trailer stored outside built a simple heater/air mover for the inside of his trailer. He used a small fan similar to what one would find in a PC. It ran on 120VAC and he wired it in series with a 100W incandescent light bulb. The whole thing was housed inside a short piece of steel stove pipe, which he suspended in the trailer. When plugged in, the fan would push cold air past the light bulb and circulate the air throughout the trailer. When the light bulb burnt out, the fan would stop, too. 

Uli

'AS'

[soa...@yahoo.com]

I've used the "Davis Air-Dryr 1000 Cubic Feet Marine Dehumidifier" for years in my trailer up here in Seattle.  Put it in the low end of the trailer and the air circulates to the high end.

I used to use something similar to damprid, but you have to regularly change/empty it.

[Matt Herron]

I second the plug-in dehumidifier.  It fits in the front of the trailer and runs all winter here in California.  It drains out a hole in the floor of the trailer made from a thru hole garden hose fitting.  That way I can cap it and keep the mice out when the hose is not in use.

Matt

[Tom Seim]

I have never used dehumidifiers in my trailers, in part because there is no electrical service available. I prefer to have fresh airflow thru the trailer instead. If you do have electrical service, I would put in a small heater instead.

Tom

[Scott Fletcher]

To prevent corrosion relative humidity levels 45% and below are required. Our trailers are not perfectly sealed which leads to air infiltration, if the air outside the trailer is above 45% RH, infiltration will bring that into the trailer.  If the trailer is exposed to temperature changes condensation can occur.  If condensation occurs in the trailer the humidity level in the trailer will skyrocket when it evoporates back out, and in someplaces you will have liquid water on surfaces prone to corrosion. I would consider condensation as the greater of the two evils.

A heater that maintaines the temperature in the trailer above the condensation temperature, will prevent condensation,  however it won't necessarily maintain the relative humidity level below 45%

The moisture absorbent materials like damp rid will dehumidify the surrounding air, until they become fully saturated, then they come to a dead stop.  Condensing water out of air, creates a vacuum, which increases air infiltration.  Combine that with poor air circulation,  and I can't see them effectively reducing humidity in the trailer.  They will make you feel like you have done something, so if you are a fan of placebos, use them.

A small dehumidifier, with the return ducted to the other end of the trailer, will control humidity below 45%, provide air circulation, and probably provide enough heat to keep everything in the trailer above the condensation temperature. Small is a relative term, the AprilAir E050 is 9x9x25", and at 50 pints per day significantly oversized.