Dehumidifier?

[SKMT]

I bought a trawler a year ago, and have been living on the hook in Miami since. My boat is about as well ventilated as they get, and it's basically always wide open except at night or during a downpour. Even at night or during rain, theres 3 port holes, 1 window, and 1 or 2 doors that stay open.

My question is about dehumidifier use. I've read plenty of threads where people swear by them as if it's a boating necessity to run them habitually. So i'm wondering if its something i really should be doing? It's florida, so of course it's humid (particularly in summer). Clothes in closet and bedding has that slight dampness (in the summer). But there's no visual mold or associated smells anywhere.

Logically, i could close every port/window every morning while I run the generator, and in the process run a dehumidifier for an hour. But I'm just wondering if there's any purpose to justify the effort and having a bulky dehumidifier laying around, considering the boat is gonna be wide open the other 23 hours of the day?

[slug]

Originally Posted by SKMT

I bought a trawler a year ago, and have been living on the hook in Miami since. My boat is about as well ventilated as they get, and it's basically always wide open except at night or during a downpour. Even at night or during rain, theres 3 port holes, 1 window, and 1 or 2 doors that stay open.

My question is about dehumidifier use. I've read plenty of threads where people swear by them as if it's a boating necessity to run them habitually. So i'm wondering if its something i really should be doing? It's florida, so of course it's humid (particularly in summer). Clothes in closet and bedding has that slight dampness (in the summer). But there's no visual mold or associated smells anywhere.

Logically, i could close every port/window every morning while I run the generator, and in the process run a dehumidifier for an hour. But I'm just wondering if there's any purpose to justify the effort and having a bulky dehumidifier laying around, considering the boat is gonna be wide open the other 23 hours of the day?

First off...get any salt out of the interior of your boat

maintain a dry bilge

As for dehumidifier ...good question

I have never ,in 40 years living on boat s, used a dehumidifier

If you use air conditioning , a dehumidifier could be helpful

In some regions...hot, cold condensation forms inside the boat, a dehumidifier is helpful.

[Pizzazz]

I have had a number of dehumidifiers on the boat and my conclusion is that they do not work well. You need an air conditioner, especially if you have a trawler and are not power constraint. I am in Socal, though.

Dehumidifiers work well if you are off the boat, you close everything down and run it continuously. In this case, they will dry up the air well. As soon as you open a hatch the humidity level between inside and outside will quickly equalize, within a few minutes. If it is warmer inside you will measure lower relative humidity. If it is colder, you will measure higher relative humidity inside.

An air conditioner allows you to lower both temperature and humidity if you keep the boat closed up and it also freshens the air. It is best to get a marine air conditioner but if you have the space you can also get one of those dual hose portable units that draw and exhaust hot air. They work well if installed correctly. In the winter, you want a good source of dry heat which could be forced air, hydronic or electric as you please.

SV Pizzazz

[HopCar]

If you don’t have visible mildew and it doesn’t smell bad I wouldn’t worry about it.

I couldn’t get good enough ventilation on my boat to prevent mildew but my boat lived at a dock with power. A dehumidifier was a simple solution.

[tkeithlu]

We use a small dehumidifier when off the boat and it's closed up, and it prevents mildew and general dampness. Air conditioners are dehumidifiers; that's why they drip. Your description of your being on the hook and opening the boat up doesn't leave much use for one.

[Lepke]

An hour a day in a humid climate isn't going to fix your problem. But, you could make sure your closets have good ventilation and air your bedding. Before foam mattresses. we aired bedding in the navy. On my boat I use small, computer 4x4 fans to power vent my closets and cabinets. I also vent the bilge areas. I'm in a cold, damp climate. Oregon. I run a stove and current relative humidity is 85 outside and 36 inside.

[Bill O]

Originally Posted by Lepke

An hour a day in a humid climate isn't going to fix your problem. But, you could make sure your closets have good ventilation and air your bedding.

+1 for proper ventilation in your cabinets/closets. Many boats are built w/o louvered doors/caning or some other way to add at least minimal passive air flow into cabinets. Have inspected many boats w/solid cabinet doors in the tropics and most of them were moldy.
If you do not have ventilation/have solid doors, then a good project would be to add vents to help create an air flow. Smaller cabinets may need only one, but a taller closet may need 2 (top & bottom). As suggested, muffin fans can be used to create a positive air flow if the passive air flow is not enough.
The only other way would be to close up your boat (especially in the summer) and run the AC. (I'm w/you on keeping the boat open as much as possible, but sometimes you gotta do it). Those free stand home type dehumidifiers are really power hogs and somewhat inefficient in removing humidity compared to the AC unit.


Bill O.

[SKMT]

Originally Posted by Bill O

+1 for proper ventilation in your cabinets/closets. Many boats are built w/o louvered doors/caning or some other way to add at least minimal passive air flow into cabinets.

Bill O.

My closets are louvered.

To be clear, I hardly consider slightly damp linens much of a problem. I was just describing the only symptoms of humidity I have. I will keep the computer fan concept in the back of my mind though.

Based on the replies, doesn't sound like I'm missing anything by not running a dehumidifier. Thanks for the responses everybody.

[redneckrob]

I'm one of those guys who swears by a dehumidifier but would advise you to just keep doing what you're doing. I think most of us that are advocating for them have boats that spend time unoccupied, when they're very beneficial. I don't even know take mine with me when I'm actually using the boat like you are.

[Waterford]

I live on Puget Sound and sometimes it stops raining here. During winter months, when the boat is closed up, I leave a dehumidifier running. It sits in my galley sink and drains overboard. The model I have has an internal humidistat and cycles on only when the humidity gets above the percentage I set. I also run a small clip-on fan that pushes air down the companionway to keep stateroom and head dry.

[Woodland Hills]

We have two 30 pint dehumidifiers and run them 24/7 set to 50% humidity. I consider a dry cabin to be a quality of life issue: we are simply more comfortable in a dry room. We also air condition the boat and usually keep it closed up although not always. When it is cool enough we ventilate the main deck salon area in the day and close it up at night. Either way the humidifiers run off and on and we dump the water every other day when closed up and daily when opened up.
If the humidity does not bother you keep doing what you are doing. If, like us, it does, than dehumidify. We are transient full time liveaboards and rarely get billed for power by the ah instead paying a flat daily rate. Thus it essentially costs us nothing extra to use as much power as we want so there is no cost penalty.

[GreenWave]

Originally Posted by Waterford

I live on Puget Sound and sometimes it stops raining here. During winter months, when the boat is closed up, I leave a dehumidifier running. It sits in my galley sink and drains overboard. The model I have has an internal humidistat and cycles on only when the humidity gets above the percentage I set. I also run a small clip-on fan that pushes air down the companionway to keep stateroom and head dry.

What kind of unit do you have? Details, price, source?

[TravellingKiwis]

Live onboard modern catamaran in Caribbean. No dehumidifier yet but looking at one for occasional use when humidity high at night or when not onboard for a while. I would buy a Meaco MeacoDry 'ABC' Range compressor 10 or 12 litre compressor dehumidifier.

Factors in choice are:
1. Energy efficiency
2. Quiet
3. Size
4. Features eg timer, drain pipe.

For me this ticks all but I recognise as a UK company, supply and support in US / Caribbean would be an issue.

The dehumidifiers from this company have garnered a number of awards and this particular model is the successor of this unit recommended by PBO.. Practical boat owner.

[desodave]

You say that your boat is basically wide open when you're on it, so I don't see any use for a dehumidifier. You'd just be wasting $$ imo trying to dehumidify a constant source of new fresh outside air. You'd have to have a closed boat for it to make any sense. I don't use one even in the wet winter months here - good ventilation and a little heat instead.

[tkeithlu]

Here's the small one ($50) we use. I rigged it with a 15/64" hole in a lower corner of the small tank, pushed a 1/4" hose though the hole, set it on the counter by a sink, and let it drain into the sink. I'm running this one on 12vDC although its 120vAC power supply produces 9vDC. It doesn't seem to mind.

https://www.amazon.com/Pro-Breeze-El...s%2C519&sr=8-4