De-humidifiers

Interesting interpretation of the posts so far. Can you point us to any small recreational boat that has "modern airhandlers" built in? I haven't seen one as you have described it, nor have I seen this equipment advertised as available from any vendor for installation on a small boat.

I guess if you are looking to have a superyacht in the 150'+ class built, you can have anything you want installed.

DDW said:

Interesting interpretation of the posts so far. Can you point us to any small recreational boat that has "modern airhandlers" built in? I haven't seen one as you have described it, nor have I seen this equipment advertised as available from any vendor for installation on a small boat.

I guess if you are looking to have a superyacht in the 150'+ class built, you can have anything you want installed.

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YOU mentioned small boats, I didnt. I was quoting you. Now you compound that with the false assumprion of 150 footers, I mentioned, "tight, well insulated boats".. BTW, what did you think of that guy's ridiculous notion of an airvhandler blowing up a boat by excess pressurization?

JWellington said:

YOU mentioned small boats, I didnt. I was quoting you. Now you compound that with the false assumprion of 150 footers, I mentioned, "tight, well insulated boats".. BTW, what did you think of that guy's ridiculous notion of an airvhandler blowing up a boat by excess pressurization?

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Not sure why you are fixating on the pressurization comment. It was a (presumably) tongue-in-cheek comment about passive ventilation and not directed at you.

In the unlikely event that you are interested in learning more about this topic, it will be worth knowing that an air handler is one component in a split HVAC system. Knowing that will help in the research you are sure to do to gain a complete understanding of the process and equipment.

Small boats - less than say 75' - is generally what this forum is about.

What I think is, there aren't any air handlers installed on small boats that circulate outside air. And apparently you don't know of any either. A "tight" boat doesn't have a fan blowing air through it....

guy with a boat said:

Not sure why you are fixating on the pressurization comment. It was a (presumably) tongue-in-cheek comment about passive ventilation and not directed at you. .

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In post #22 I do believe Marco has coined a new topic for TF. Exploding boats due to salt laden dehumidifiers.

This thread is following a very familiar pattern.

Water vapor does not contain salt. Dehumidifiers cause the water vapor to condense out of the air. Essentially, a dehumidifier produces distilled water.

But a dehumidifier does not remove salt, because there is no "salt vapor" in the air. Salt is in aerosols -- that is, tiny floating particles of salty water. But if the boat is closed up, aerosols will not come inside the boat in any noticeable amount. Water vapor will come inside the boat because the air is humid -- that is, it contains water vapor.

Salt is not an issue inside a closed boat.

DDW said:

Small boats - less than say 75' - is generally what this forum is about.

What I think is, there aren't any air handlers installed on small boats that circulate outside air. And apparently you don't know of any either. A "tight" boat doesn't have a fan blowing air through it....

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Resolved...'small' is too subjective a term to have any meaning. Apparently 'tight' is too. Boats that have hvac systems tend to be tight by my definition. In any case I never even mentioned anything about size, but about the salt content in air. And in boats with modern air handlers, the question of the OP has been resolved....lovely cool or warm dry air with little salt.

BlueMoon1975 said:

Water vapor does not contain salt. Dehumidifiers cause the water vapor to condense out of the air. Essentially, a dehumidifier produces distilled water.

But a dehumidifier does not remove salt, because there is no "salt vapor" in the air. Salt is in aerosols -- that is, tiny floating particles of salty water. But if the boat is closed up, aerosols will not come inside the boat in any noticeable amount. Water vapor will come inside the boat because the air is humid -- that is, it contains water vapor.

Salt is not an issue inside a closed boat.

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Very well, but people do open doors to go in and out, and to the extent they do, salty air will enter. But agreed, if mostly closed, not a problem, and the air handlers deal with it.

psneeld said:

While I believe dehumidification reduces both water vapor (and it's salt aerosols), there is still salt aerosols in the remaining water vapor.


Research has shown salt aerosols as far inland as 100 miles (in Florida).

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Having lived in Southern California, 6 miles inland without a/c in the house I’ve had issues with electrical outlets corroding, fixtures corroding and electrical panel CB corrosion.. same thing in So Florida, though in south FL I had A/C. All the boats I’ve had required regularly maintenance to stay ahead of the salt, both inside and out.

Does a humidifier make sense with a wet bilge?

I don't know if this question is hijacking this thread. If it is the mods can move it.

I have a wet bilge so there is always water in the boat. I also have a full winter cover, (Lohman cover) from October to March/April. I leave the port holes open to enhance air flow.

Vancouver is pretty wet at the best of times in winter, so there is a lot of humidity. Would a humidifier in such a wet environment be worth it?

If you can shut the boat up pretty tight, and keep the bilge covered, a dehumidifier may help. The boat is kept in the water? Where is it leaking so that the bilge stays wet?

If you leave the ports open, or the flooded bilge is open to the cabin, running a dehumidifier may be a waste of time. The dehumidifier will dry out the bilge over a week or two, but not if water continues to leak in.

If I was to get a humidifier I could crank up my stuffing box. I used to do that in the winter but I’ve gotten lazy on a few things.

Nightflyer said:

Having lived in Southern California, 6 miles inland without a/c in the house I’ve had issues with electrical outlets corroding, fixtures corroding and electrical panel CB corrosion.. same thing in So Florida, though in south FL I had A/C. All the boats I’ve had required regularly maintenance to stay ahead of the salt, both inside and out.

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Yes, thanks, that was the concern. Now we've found out there are about 3, or even 4 different air handler systems, some better than others at taking out the salt. Ill find out which is the best.

Air handlers are designed to move air around. That's all that they do. They don't heat up or cool down, they move air. Air conditioners, on the other hand, exist only to cool air by removing heat from the outdoor air.


https://www.goodmanmfg.com/resources/hvac-learning-center/hvac-101/what-is-an-air-handler

psneeld said:

Air handlers are designed to move air around. That's all that they do. They don't heat up or cool down, they move air. Air conditioners, on the other hand, exist only to cool air by removing heat from the outdoor air.


https://www.goodmanmfg.com/resources/hvac-learning-center/hvac-101/what-is-an-air-handler

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Modern, marine, HVAC....does it all...even removes mold, bacteria, etc. They've got it down.

JWellington said:

Modern, marine, HVAC....does it all...even removes mold, bacteria, etc. They've got it down.

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Please provide a link to what you are talking about.


I recently researched the market and installed 3 air conditioners on my boat.


I seem to have missed all the great things in marine "air handlers" you are referring to.


The term air handler only refers to a component, not a system.

psneeld said:

Please provide a link to what you are talking about.


I recently researched the market and installed 3 air conditioners on my boat.


I seem to have missed all the great things in marine "air handlers" you are referring to.


The term air handler only refers to a component, not a system.

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Here are a few you missed in your research.....there are many more that supply any sort of marine HVAC you could need. https://heinenhopman.com/en/markets/yachting/expedition-yachts/. https://www.teknotherm.no/.........https://www.bronswerkgroup.com/hvacr/marine-hvac-r/marine-hvac-r-systems/

Water vapor

JWellington said:

How does it work with marine dehumidifiers/air handlers? They take out moisture, but what about all the salt in the air? Our new boat will be tightly closed most of the time.

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Dehumidifiers remove water vapor, which is essentially distilled water. There is no salt in water vapor. Very fine spray particles may contain salt but I don't believe any Dehumidifier would remove salt spray. That would need to be filtered. ???

Sharpseadog said:

Dehumidifiers remove water vapor, which is essentially distilled water. There is no salt in water vapor. Very fine spray particles may contain salt but I don't believe any Dehumidifier would remove salt spray. That would need to be filtered. ������

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'may contain salt'? everybody that lives near , or on the sea knows the air contains lots of salt. And modern marine hvac systems can extract it/filter it out.

grahamdouglass said:

I don't know if this question is hijacking this thread. If it is the mods can move it.



I have a wet bilge so there is always water in the boat. I also have a full winter cover, (Lohman cover) from October to March/April. I leave the port holes open to enhance air flow.



Vancouver is pretty wet at the best of times in winter, so there is a lot of humidity. Would a humidifier in such a wet environment be worth it?

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Graham, my over 40 years experience has been with boats sitting in the water year round in Puget Sound. Just because I have years of experience, doesn’t necessarily mean I have been doing it correctly all this time, however.

I have found that using a dehumidifier makes a huge difference in reducing the moister, mold, and mildew and increasing the comfort in the boat during the 3 wet seasons. What I’ve found to be the most effective is a compressor type of dehumidifier in the main cabin that drains into a galley sink and then something to cause the air to be circulated into the other parts of the boat. However, even the small compressor types of dehumidifiers are relatively heavy and not always easy to store.

I have also used multiple small peltier dehumidifiers. They are quieter and easier to move and store. I have found that they are not nearly as effective as they compressor type but they have been “good enough”. I also have found them to be less reliable. I’ve never had a compressor dehumidify fail on me, so far I’m 2 for 3 with the small peltier dehumidifiers. Only one is still functional.

I just ordered a desiccant dehumidifier yesterday. It is the type have uses a bit of heat to remove the moisture from rotating panels that are coated with a desiccant. It should be lighter in weight, and quieter than the compressor types. I’ll see how it works out.

Anyway, in your situation when you keep your boat covered, I’ would just use a small compressor dehumidifier and have it drain into a galley sink. I would also see what you can do to remove more water from your bilge. If you can’t stop the leaking, consider using a micro bilge pump such as “dry bilge” to remove most of the water from the bilge and keep it out.

Just my opinion base on my experience. Your experience may vary.

"If I was to get a humidifier I could crank up my stuffing box."

A simple" Plan B " might be a copper tube to the stuffing box and a cup or other grease fitting.

Very little effort to stop the dripping, till next boat use.

JWellington said:

In any case on boats with modern air handlets the humitity can be set to whatever one likes best.

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This really piqued my interest. Just like the A/C display, I could set the % humidity? What model units do this? I got rid of my dehumidifier lacking space to store it but, wishing I hadn’t.

JWellington said:

Here are a few you missed in your research.....there are many more that supply any sort of marine HVAC you could need. https://heinenhopman.com/en/markets/yachting/expedition-yachts/. https://www.teknotherm.no/.........https://www.bronswerkgroup.com/hvacr/marine-hvac-r/marine-hvac-r-systems/

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I scoured both those sites and there was a dearth of specs. Everything was obviously oriented and marketed to commercial and super/mega yacht size boats. What few things I did see like a self contained unit- a minimum of 188 kg. A few other pieces of equipment operating at 460 VAC. I’ll go out on limb and suggest that no one’s boat here operates at 460 volts.

While the tech may exist, it appears little is aimed toward smaller recreational boats, the focus of this forum. Like psneeld, I have a 40’ boat with 3 self-contained A/C units. That configuration probably represents most of the boats discussed on this forum with a few split systems thrown in. Fresh air ventilation, air purification, humidity control all bundled up into one? Sign me up if such a thing exists for us and can fit in available space.

It sounds like you’re looking a larger boat that may avail itself of commercial equipment and that’s interesting but not exactly practical for some of us. I nonetheless look forward to hearing about the specific products you have chosen and spec’d and opportunities for downsizing to the smaller boat segment.

Porgy said:

This really piqued my interest. Just like the A/C display, I could set the % humidity? What model units do this? I got rid of my dehumidifier lacking space to store it but, wishing I hadn’t.



I scoured both those sites and there was a dearth of specs. Everything was obviously oriented and marketed to commercial and super/mega yacht size boats. What few things I did see like a self contained unit- a minimum of 188 kg. A few other pieces of equipment operating at 460 VAC. I’ll go out on limb and suggest that no one’s boat here operates at 460 volts.

While the tech may exist, it appears little is aimed toward smaller recreational boats, the focus of this forum. Like psneeld, I have a 40’ boat with 3 self-contained A/C units. That configuration probably represents most of the boats discussed on this forum with a few split systems thrown in. Fresh air ventilation, air purification, humidity control all bundled up into one? Sign me up if such a thing exists for us and can fit in available space.

It sounds like you’re looking a larger boat that may avail itself of commercial equipment and that’s interesting but not exactly practical for some of us. I nonetheless look forward to hearing about the specific products you have chosen and spec’d and opportunities for downsizing to the smaller boat segment.

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Like many people who know boating through the internet...there is a big disconnect into their dreams and realities.


I too looked over those sites...can't believe the one on expedition yachts didn't grab my attention, after all I own a '88 Taiwan beast, I must be one of the very few here with such a tiny archaic boat.


For the unlimited budget....sure anything can be done. Even watermakers are neanderthal compared to NASAs ability to recycle your own wastes for the right price.

Porgy, you looked at 'both' citations? There were three. Here is a forth one, https://premaberg.com/, another one that says they will cater to the specific needs of you and your boat. That some people cant afford modern hvac systems is a seperate issue. I too often feel like I deserve more in life.
But the issue is resolved, the salt content of of onboard air can be treated, just as moisture level, and other air concerns.

Psneeld, thanks for conceding that my research found what yours didnt. From one of the 4 requested citations, they even mention their technique, "How moisture separators work



"At the heart of a Premaberg separation and filtration product is a bank of inertial vertical vanes. Their design causes the incoming air to take a tortuous path setting up inertial forces resulting in impingement of the moisture droplets on the vane bodies.

Each vane has multiple changes in direction and multiple catchment pockets to trap the moisture droplets separated by impingement.

These droplets drain vertically downwards to a catchment trough underneath the vane section.

Additional stages of separation and/or filtration may be added depending on individual requirements."

I may have conceded something, but your guess is way off.


Happy fantasies!

Nightflyer said:

Having lived in Southern California, 6 miles inland without a/c in the house I’ve had issues with electrical outlets corroding, fixtures corroding and electrical panel CB corrosion.. same thing in So Florida, though in south FL I had A/C. All the boats I’ve had required regularly maintenance to stay ahead of the salt, both inside and out.

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Exactly , its a big concern for many, in various ways.

In addition to the corrosivness of salty/humid air on materials, there are also various adverse effects on certain peoples bodies, it makes some people feel slimy, and as mentioned above, affects hair, a major contributor of the ill-temperament of some of our admirals. Here is a citation for that too: "Salt can create some volume and remove oil, but on the flip side, it can be very harmful,” says Mia Emilio, senior stylist at Devachan Salon. “We have to think about the adverse effects of our styling agents ... You have to decide if achieving volume is worth the price of dry, dull, and matted hair.”

Turns out whether you’re spritzing a salt spray or taking an actual dip in the ocean, salt works the same way: It pulls oils and natural moisture out. But if too much moisture is lost, the result is parched, brittle locks.

"In its worst form, salt water damage causes the ends of the hair to split, and breakage can begin,” says Elizabeth Cunnane Phillips, trichologist at Philip Kingsley"

And......... ""Your hair's water content is what makes it stretchy, elastic and moisturized -- kind of like your skin. And, similar to your skin and the rest of your body, your hair can become 'dehydrated' and dry if too much moisture is lost through evaporation. And even more so if that moisture is not replenished," said Elizabeth Cunnane Phillips, trichologist at Philip Kingsley. "As the sea has high salt content, it is osmotic, meaning that it leaches water out of your hair. The result? Dry, parched and brittle locks."