Dehumidifier good or bad idea?

[SteveK]

We keep our crawl space between 45 to 50% humidity and do not get mold.

Thanks. Getting a dehum, maybe will put it in the engine room as the salon is at 48% right now.

 

[Northern Spy]

The little dehumidifier the ducatihottie has can run all the time. It won't dry the boat out in a Seattle winter.

I have a similar one (eva-dry)

As it is a Peltier effect unit, sometimes the cooling plate will ice up. Check it in freezing weather. In fact it pretty much stops working if the boat gets too cold.

PS: Does anyone else feel dirty typing out ducatihottie?

 

[firehoser75]

I usually also run one ceramic heater set to the 750 watt setting on low. It only turns on to keep the temps in the salon at 50 degrees and I also run a 250 watt oil pan heater on the main engine, leaving the ER hatch open and the ER vents blocked with foam. I regularly (each visit) check the amperage for the A/C current and it never exceeds 20 amps. I also check the entire A/C system (shore power cord, outlet, etc.) with an IR gun (temp). So far, never a problem. Also, all floor hatches are left open, as well as cupboard doors and drawers, etc.

 

[Ducatihottie]

Northern Spy, There's a funny story how I started using "Ducatihottie". Remember "EarthLink"? Upon opening the account the operator gave you three chances to pick an email address. If you failed they would pick one for you. My first two picks were taken. Then my wife screams out, "Ducatihottie" and the operator said 'OK' before I could change it. So I got ducatihottie@ertlink.net.

Now I have similar Google accounts.

Thanks, I'm starting to open every cabinet as well along with my bathroom doors, anchor box and more.

I also have about a ten gallon brown water tank for my shower with a pump and float. If by any chance it overflows or the pump or float break, it the water will drain into my bilge pump area. I guess it should be safe placing it in my shower.

I'm also happy someone said here in Seattle I don't have to worry about my wood drying out????

 

[mvweebles]

In Florida, difficult to get below 60% dehumidification much of the year. Dehumidifier will run constantly and never get there. While I can only speak to home vs boat in Florida, 60% seems to be a good setting.

As far as over-dehumidification, that's funny. Sales people can be so creative. I am writing from a cabin in Colorado with several pieces of furniture from the 1940s that were built with veneer, a common technique at the time. Cabin has spent the better part 100 years at ridiculously low humidity - rarely above 35%. Its a perfect climate for preserving almost anything. I have 30 year old tools that look brand new, a far cry from Florida where tools start showing signs of oxidation in days or weeks.

FYI - R69S (BMW), a "barn find" I've had for 35 years. Time flies.

Peter

 

[NorWyn]

We also use a 30 pint dehumidifier with excellent results. Keeps bedding dry, no mold issues etc. and all the other good stuff already mentioned. As with others we keep the hatches, cupboard and head doors open.

As far as fire hazard goes, I check the unit for excessive heat each time I am at the boat and keep the vents well clear of any obstruction.

One thing to be aware of is that most units do not run well at colder temperatures (according to my research below 60 degrees f). At lower temps the coils can ice up and while (perhaps) not a fire hazard the unit won’t work well and may suffer damage. (I had one fail from this issue).

I run a marine specific electric heater (about $100) in colder weather to keep the cabin around 50 degrees f and the humidity seems controlled by that in the winter months as indicated on a combined digital temperature/humidity gauge (hygrometer) I have on board (about $20).

 

[RLKramer]

Our prior owner used to keep his boat on the hard in FL and would use a portable (with wheels) AC to cool and de-hu the boat. He would get fresh and exhaust the heat through the dryer supply and return outer vents. He had a pretty neat set up-- that way he could run it just fine without having to vent it through an open window. He ran the condensate down a hose into the bathroom sink drain. He was happier doing this as it kept the boat cooler as it baked in the heat on the hard.

We use a de-hu in the kitchen sink and let it drain into the side of the sink WITHOUT the disposal and it goes straight over board, not through a pump. We just replaced a disposal that started leaking out of the bottom of the motor so I did not want the water to run through it again and start the rusting all over again. See picture.

I also have 4 fans ($15 ea Honeywell Amazon) strategically placed in the living space and the engine room to keep the air moving.

I dont use the stuff but the prior owner used a chemical called Home Zone that he put on paper plates and had strategically placed to keep the mildew at bay. Picture attached.

 

[Capn Skippy]

I've been reading this thread with interest... I'd be interested in posts of specific brand/model #'s of units everyone is using... seems this time of year, at least locally, no one stocks them.

 

[NorWyn]

I've been reading this thread with interest... I'd be interested in posts of specific brand/model #'s of units everyone is using... seems this time of year, at least locally, no one stocks them.

We have a Toshiba 30 pint...don’t have the model # handy but I did look it up after my previous post and it seems to operate effectively above 40 degrees f.

If you are in a colder climate I’d suggest checking the operable temperature range for the model you are considering, as well as watching the coils for signs of icing.

Surprised you can’t find them...our local Home Depot and competitors have multiple models in the $200-$400 range.

 

[DDW]

Regarding humidity, it isn't the absolute humidity that affects woodwork, it is the change in humidity. If the boat joinery was done at 80% and you go to 35%, you should expect things to shrink and joints to open. Going the other way usually has less problems, though you can still get problems: panels and flooring buckling, that sort of thing. If the boat is used to fairly humid conditions and the joinery looks good, over dehumidifying can cause trouble. That's why people say to leave it between 45 and 55%. Much above 60% and you may start seeing mold. Whether you can get that low depends on how tight the boat is and how big the dehumidifier is. It doesn't take much of an air leak to defeat a dehumidifier.

 

[firehoser75]

Cap. Skippy,
I use a Whirlpool 30 pint dehumidifer and a Fridgidaire unit of the same size. I bought them several years apart, one at the big box Home Depot and the other on Amazon just recently. No afiliation with either.

 

[stiggy]

Lots of good info here. Shawn from MVFreedom just installed a nice dehumidifier unit in their N43 on their latest episode which brought me here searching for options.

 

[magna 6882]

I used a fridgidare unit in the motorhome before we built a garage for it and it seemed to work well. In the boat i want a more permanent solution so i went with a decadent style unit to install permanently. Its only 8x8x12.
It was recommended by a you tube couple we keep up with.

https://www.amazon.com/ECOR-PRO-EPD50-PRO-Desiccant-Dehumidifier/dp/B07V3GWVWQ


Should arrive in the next day or so.

 

[Marco Flamingo]

Thanks, I'm starting to open every cabinet as well along with my bathroom doors, anchor box and more.

That, and opening a couple of rain-proof windows, ports, or hatches, is all I've ever done in Seattle. I have a small collection of dehumidifier gadgets that were removed from boats that I have bought over the years. Never used them. Nothing seems to work like fresh air. No mildew, but I have gotten a few spiders. They tend to make a web right where the air blows through the opening.

 

[DDW]

I used a fridgidare unit in the motorhome before we built a garage for it and it seemed to work well. In the boat i want a more permanent solution so i went with a decadent style unit to install permanently. Its only 8x8x12.

The nice thing about those units is that they are a desiccant type with a separate exhaust port, so both the moisture and hot air can be exhausted outside the boat. A home style compressor dehumidifier will add about 400 watts heat to the boat which may be unwanted. A the pricey end though.

 

[Alaskan Sea-Duction]

I have 2 reverse heat/AC units on ASD which does a good job removing humidity.

An alternative is a 5 gallon bucket filled with BBQ charcoal.

 

[TollerTrawler]

I have a large dehumidifier that I use on a timer for 8 hours a day (marina electricity cost is a factor). I have noticed that around 3 degrees C, the humidifier starts to ice up, and becomes ineffective (actual ice layers form on the radiator portion). I'm changing its use cycle to the middle of the day when it's warmer on the boat.

 

[Capt Ray]

Highly recommend viewing this episode. These trawler folks have a nice series of Youtube videos. This one is on their successful dehumidifier project.

 

[Sofa King Fishy]

I do the same. Works fine.

Yeppers- Nailed it! I do the same but lash it under my saloon table & drain into the bilge all winter (I’m a live aboard). Keeps things dry & keeps the bilge fresh as well.

 

[CarlF]

As mentioned, if you are in a colder climate, check your dehumidifier manual for temperature range. Most say to use them only above 60F. You can use them in colder temperatures without hurting it but it will remove less and less water until at around 40F it stops removing any water.

The desiccant type work well down to freezing. Here's one I got that has worked well on my boat. It has a smaller capacity than many dehumidifiers but you don't need as much moisture removal in winter. https://www.amazon.com/gp/product/B07X43RGML/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

As to fire - the bigger fire risk is in the wires getting to the dehumidifier. If you must use an extension cord get a heavy duty one and not one you find in the HD bargain bin. Check the outlet on the boat for any sign of scorch marks. If there are, replace the whole fixture. Do not plug more than one heater/dehumidfier into the same boat circuit. Next, unplug both ends of your shore power cable and look for scorch marks. If any, replace the cord. Squirt some contact cleaner on the plug tines and polish. Finally, be absolutely sure that the shore power cable plugs are fully seated, turned all the way and solidly locked in their sockets. Check occasionally during the winter that they are still locked.

 

[Ruffryder]

We have a 30 pint Kenmore in the salon & 1 pint in our master suite.
Humidity level set at 60%, we pull about 3 gallons a week.

 

[Hippocampus]

Still think this decision is predicated on where you lay up and when. While the boat is being actively used this is usually a non issue. The boats HVAC system suffices. Main culprit is mold not wood movement. . The wood floors in your house expand and contract without producing troubles. Most coatings including varnish will tolerate this as Will wood adhesives Particularly teak and cherry hard woods. There’s virtually no unsealed soft woods in a boat to speak of.
The choice is therefore cold and wet, hot and wet or warm and wet. I have no experience with cool and wet so won’t comment on that situation.
For cold and wet simple desiccants will suffice. Using New England as an example have found if you hang a few and place a tub in each sink then change them out periodically that suffices. Add in some tea tree oil and no damage or mold come spring.
For warm and wet such as lower Chesapeake down to Georgia desiccants and or a dehumidifier is enough. If dehumidifier is set reasonably so it shuts off periodically fire risk is low.
The subtropical zone is where using a AC unit starts to make sense and an AC unit makes better sense than a dehumidifier in the tropics. Here boats are laid up in the summer not winter. Humidity is quite high. The AC unit is usually a unit made for land use to cool a room. It’s set up to run on what ever configuration that the local power grid uses. It’s placed outside the boat with it’s cooled dehumidifed air ducted into the boat. Down there heat and humidity are the villains to destroy boats and mold flourishes. Often a sun cover is placed over the boat to prevent UV damage and decrease the temperature. Without AC and a cover temps can get over 100f inside a boat. The AC also circulates the air which is something a dehumidifier does poorly. Add in a fungicide (I use tea tree oil) and the boat is perfect on your return.

 

[gsebastian]

I use a dehumidifier placed over the galley sink sitting on a wire rack from the fridge and have a multi on-off timer that runs it for two hours 4 times a day when I'm not aboard, works great.

 

[rgano]

4. Can I just get one, "great job, why didn't I think of that"?

Thanks

OK. Great job, but like many others, I did think of that - sorry couldn't lie.

 

[Ralsy]

https://youtu.be/1knudST2M_0

Have a look.

 

[Ralsy]

Ahh, I just noticed that this was already posted.

 

[kimdabe]

dehumidifier or AC

I use to use a dehumidifier but a fellow boater convinced me to use my AC in dehumidifier mode. Both seemed to work, but I admit that I have not calculated the cost of running one or the other. If I wear out a dehumidifier I am out $100. If I wear out an AC, I am out big bucks. That said, will someone give me an argument for one over the other.

 

[Tator]

I've been thinking about replacing one or both electric heaters that we use on our boat over the winter in Petersburg in SE Alaska with a good dehumidifier. The one that I am thinking about using says that if it ices up, the fan continues to blow over the coils to de-ice it. Any experience on this? The boat is checked weekly by a boat watcher-not us. The costs of running the electric heaters is often more per month than the moorage charge. The boat is kept in the water as the water never freezes.

Tator

 

[Desolation Dan]

I too use a dehumidifier in my trawler. It sits on the galley counter with the hose into the sink. I follow the advice of the former owner and make sure I plug it into a 110V outlet in the boat that connects to the shore power and not to an outlet running through the inverter. If the power goes out the dehumidifier stops and I avoid the risk of the power remaining off long enough to run the batteries right down due to it coming from the inverter. That could ruin the batteries- an expensive repair. I do the same with any fans or heaters I put in the engine room or staterooms over the off season. I do visit the boat frequently but do not want to risk having no power for the bilge pumps or ruining the house battery bank.

 

[Hippocampus]

Have the dehumidifier mode for the boats AC. Never use it. What I was talking about was a independent AC made for land use. They’re just a couple of hundred and are run as AC.