Winterizing for PacNW

[guy with a boat]

I'm going to revive this thread now that we are into colder and wetter weather in the PNW/southern BC area. This is our boat's first winter up north (Victoria area) and our California/Florida winter prep knowledge isn't helping us much. We go back and forth to the boat as time permits, but the boat will sit for weeks at a time during the winter season.

I have two condenser dehumidifiers on board that are set to auto at 55%. I only recently became aware that these apparently don't work in colder (sub 60F) weather. When we last left the boat, the humidity was in the 90's outside, so I set up both units and left them on. They worked fine when we were are onboard and have the boat warm. My question is, what will they do now that the boat interior must be in the high 40's? Will they not go on because of the low temps? If they do go on, will they be ineffective? Is is unsafe to have them on?

If these condenser dehumidifiers shouldn't be on in the winter, what should we do in their place? Do electric dessicant units work well enough? It is raining there today with humidity in the 90% range. I don't want to come back to a moldy boat. We have two small oil-filled heaters on the lowest setting and left the water heater on. The intent is mostly to avoid risk of freezing pipes; I don't think they will warm the interior much at all.

Tips on how to keep the interior dry?

 

[rslifkin]

Some compressor dehumidifiers will work fine down to 40* or so (I've got one in my garage), they just become less effective as the temperature drops (as they can't run flat out all the time or they'll ice up). And they'll never get the dew point below freezing. If you can keep the temp up around 50*, the dehumidifiers will be at least somewhat effective.

Plus, if the outside temp is 20* or so cooler than the inside temp, it'll often stay dry enough without the dehumidifiers anyway.

 

[Ka_sea_ta]

I leave mine turned on (no shut off for lower humidity) and put it on a timer to run about 8 hours a day.... A couple of fans to move air from remote areas of the cabin and no moisture issues in the boat.... Beware of leaving a de-humidifier running 24/7 as they can dry out interior wood causing it to shrink... this is not good if it is a window frame...

 

[Moonfish]

Tips on how to keep the interior dry?

Air movement is key, in the PNW. Even if heat and dehumidification are absent, low-power fans will help a lot.

And although not directly related to keeping the boat's interior dry, I'll reiterate the use of Kanberra Gel. Especially in our humid marine environment, the evaporating tea tree oil gets in the air and on surfaces to help kill mold and mildew.

Along with a bunch of H2Out Space Dryers strategically placed throughout the boat, we've used Kanberra Gel for 9 years and swear by it. In fact, my wife is their unofficial top testimonial salesperson! (At boat shows they will find her to talk to potential customers in the Kanberra booth...)

If any TFers wants to buy some, PM me and I'll give you a discount TF coupon code in our online store.

 

[Stabi]

We also have our dehumidifier set on a timer, 12 hours on during the day, off at night. Along with the Kanberra Gel Tea Tree oil in the staterooms, we have to date never had a mold problem.
Kanberra is the "high price spread" there are others (i.e. Tea Tree Power) that are just as effective but lower in price.

 

[gsholz]

We are in the same area and did not have a dehumidifier last winter. No issues. The only time we seem to have humidity issues (water will condense on windows/portlights) when we stay on board in the winter. This year we bought a dehumidifier to make our winter outings more comfortable. I was not planning on keeping it on when we are away.

 

[ghost]

I have used a condensing dehumidifier for about 4 years. Noticeable improvement, but I also only learned recently it was only mildly effective as the temp dropped below 50. I don’t think it matters. Before I got it, I never had a big issue in the winter, but one spring I suddenly had mold starting to grow on the windows and in a couple lockers. Luckily I caught it, but it happened suddenly. I think it’s when the temps start to rise that seems to benefit from the dehumidifier and at that point, it’s back in its effective temp range.

This is the first year I have added temp/humidity sensors. I’ve been maintaining about 59% humidity, where the background has been 85%. Last Sunday, I opened the door to my engine room and left it open. So far, I have not seen humidity drop below 80% there, so now I’m more aware as to how far the moisture is being pulled. I’ll give it more time, but a fan may be needed. Also going to add temp/humidity sensors in both the forward and aft cabins and see wha it looks like there. I know from past years that the whole boat benefits, but I’m already suspecting that I’m going to learn that some small fans may make more difference than I otherwise suspect.

 

[Northern Spy]

“The Warm Dry Boat” by Roger Mcafee is a worthwhile read if you can find a copy. Mostly writes about the importance of airflow.

 

[DDW]

I've left a boat for the whole winter in Sidney, compressor dehumidifier running 24/7 for 5 years in a row without issues. All but the very cheapest ones will shut down if they freeze, which is really the only technical problem.

 

[ghost]

Made me look. I guess mine will apparently operate down to 33 degrees and has a reverse cycle to thaw. Picked it up from a boatyard as gear taken off when selling a boat. So, it was a, if you want it, you can have it kind of deals.

http://www.ebacusa.com/hvac/CD30.html

I probably would not have chanced a $600 unit otherwise.

 

[guy with a boat]

Thanks for all the great feedback. I am happy to hear that it will likely do no harm to leave the condenser dehumidifiers running in cold weather. Next trip to the boat, I will check the specific model numbers of the units that I have and look up the specs and manufacturer info regarding cold weather. They came with the boat, but they seem to be fairly high-end units so I'm guessing they will be fine.


I'm going to add some humidity and temp sensors to the boat so I can monitor remotely. I think the combo of dehumidifiers and two small oil-filled space heaters will keep it dry enough and safely above freezing.


Thanks again for the help.