Mold on the boat

K2MSmith

Sustaining Member
Note on dehumidifiers. I have two of the heater/fan dehumidifiers I inherited from the PO. These are sold at West Marine and others. They are round about 12" in diameter and about 4" high. These dehumidifiers don't require a tank as they basically just circulate warm air; (kind of the inverse of a vaporizer) I am not sure how effective they are as I have not measured humidity with and without them running, but two seem to keep boat pretty dry. I am inclined to try a dehumidifier that does collect water in a tank to see if there is a difference but I was concerned about overflow, but it is interesting to hear from several of the posts that there is an overflow that can be run into the sink.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
One note about : 1) heating the air in your boat interior, 2) circulating the air, as with a small fan, and 3) dehumidifying the air.
#3 refers ro removing water vapor from the air, and when removed and collected it has to be further removed or emptied from the device. Usually this involves draining a collection tank. Some folks let this device send the collected liquid water into a drain inside the boat like the sink, but that requires leaving a thruhull open. And that's not a good idea for several reasons.

If you bought a device that is labeled a "dehumidifier" and it does not remove water from the air, the label is lying to you.
Usually, inexpensive heater/circulators are sold as 'heaters', and while they will circulate the damp air around, they will not an can not remove the damp.......

One good thing about any air circulation device is that, IF you have a cabin vent open to atmosphere, the humidity can equalize with the outside air, and if the outside air is below freezing the humidity will drop to nearly zero. In my damp and cold area, the ambient air is likely to be in the 40's and the humidity will be well over 60 or 70% for much of the winter. We refer to this as a high "misery index" ! :)

DE-Humidifier note: one winter I checked on a friend's big sailboat every week while he was out of town for a while. He had a real dehumidifier working (110 volt, dockside power supply) and the two gallon tank was full every week. I would lug the tank over to the companionway and empty it into the cockpit. Result was a wonderfully DRY interior. No odors from mildew or mold was present. Cushions dry. Woodwork clean. Awesome.

We have always gone with plan B, as it were. Lots of inside vents and openings to all bilge areas, all upholstery removed to home, and hatches on 'vent' position. I do have an AC portable heater handy to turn on if/when working inside.

Sort of a plan B+, is what a friend on mine does. He has a replacement hatch board with a muffin fan mounted in it and it runs all winter to remove inside air. Actually he uses it a lot in the summer, too.

The "answer" seems to be air active circulation and exchange with outside air, for a host of problems....
The solution might be different in other climates and lattitudes, atmittedly.
 

Kenneth K

Contributing Partner
Blogs Author
The non-plug-in version of the above:

Dri-Z-Air.jpg
Refill crystal packets are expensive if you buy the small sizes, but you can buy gallon-size refills at Home Depot (they sell "Damp Rid" but it's the same stuff) for about $10.
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
The non-plug-in version of the above:

View attachment 37108
Refill crystal packets are expensive if you buy the small sizes, but you can buy gallon-size refills at Home Depot (they sell "Damp Rid" but it's the same stuff) for about $10.
My forgetfulness kicked in.... yes you can use a chemical that absorbs and holds a certain amount of water vapor. And then remove the saturated crystals, dry them, and reuse them. Works better for small boats with smaller interiors, IMHO.
 

Kenneth K

Contributing Partner
Blogs Author
Dri-z-Air and Damp-Rid crystals slowly dissolve as they absorb water. They, along with the moisture, turn into "salt water" (calcium chloride) which gets dumped when you empty the collection bin. Yes, for small areas, but I keep 5 of them on my boat since I'm on a buoy without power. They collect a lot of water (a poor-man's dehumidifier). A bit slimy and difficult to clean up if spilled, though.
 

Sean Engle

Your Friendly Administrator
Administrator
Founder
...

2. Keep the air inside the boat moving and warmish if possible. I have two fans the I leave running inside my boat (berthed with shore power). The moving air helps to keep things dry.

3. Get to you boat and get it aired out as frequently as possible. If you have a leak and water accumulates, then your cabin becomes a greenhouse of damp air. Open the hatches, open the companionway, let the humidity normalize.

4. I know some people in more humid climates use de-humidifiers. It would be overkill for me in Northern California. If you have shore power accessible, this will be another way to keep your interior dry. Set up the water accumulated to drain to a bilge or some other appropriate system.
Second on dehumidifier - especially if you're closing the boat up for long period (defined as more than a couple of days). We (in the PNW) usually use a combination of heat and dehumidification to combat this....I would imagine you only need to worry about the latter. I used a standard one draining into my sink - there are small dehumidifiers like this (not a recommendation, don't have any first hand knowledge on the brand):


Basically, clean it up, then keep the air dry and moving...
 

Sean Engle

Your Friendly Administrator
Administrator
Founder
...

DE-Humidifier note: one winter I checked on a friend's big sailboat every week while he was out of town for a while. He had a real dehumidifier working (110 volt, dockside power supply) and the two gallon tank was full every week. I would lug the tank over to the companionway and empty it into the cockpit. Result was a wonderfully DRY interior. No odors from mildew or mold was present. Cushions dry. Woodwork clean. Awesome.

Basically what I'm suggesting - although it is lots of EQ - and Loren is right about closing the sink drain (mea culpa = guilty). But again, goes back to intention and how long the boat is being closed up. If you're down there frequently, then something less invasive could be done. The other thing is continuously cleaning and wiping down surfaces and removing things which hold moisture (no wet gear, wet dish towels, etc).
 

1911tex

Sustaining Member
It seems the sink thru hull is always the most used valve on the boat. In the past year, we had 2 sailboats in our marina sink almost 2 feet above water line, one due to a minute split in the hose from valve to sink (valve left open) and the other due to a worn valve (not the thru hull fitting) that began leaking even though it was closed. Both noticed by maintenance folks working on the dock. Keep the sink thru hull closed when leaving the boat for a period of time. And replace the valve every few years when on the hard. I have been guilty and suffered the consequences a few years ago on another boat...but I was lucky...I was there when the water creeped over the sole. Also due to a minute leak in the hose.
 

Kenneth K

Contributing Partner
Blogs Author
In the past year, we had 2 sailboats in our marina sink almost 2 feet above water line, one due to a minute split in the hose from valve to sink (valve left open) and the other due to a worn valve.....
By the time the marina crew notices the boat sitting low in the water, significant damage is likely already done--wet sole, wet cabinetry (speaking of mold issues), maybe some wiring already submerged. Not long after that, the engine bed probably starts filling with water.

Wonder why more people don't install backups? A high-water alarm could draw attention sooner. Better yet, some electronic bilge pump switches energize a signal wire if the pump runs longer than 2 minutes. Wired to a strobe or alarm, this could draw attention within the first few minutes of springing the leak.

Seems worth the $200 and the wiring time/labor costs required to install such a system. That said, I still don't have one myself, though I have been building it into ongoing electrical and bilge upgrades.
 

1911tex

Sustaining Member
As far as mold is concerned....this is the air purifier I have had for a year now....yes kills mold as well as other spores, etc. I really like it because it has 3 washable filters (don't have to keep buying new ones)...all I typically do every couple of weeks is dunk the filters over the side in a net, flush them up and down a few times, lay them out in the sun for a couple of hours and re-insert. This is a job I usually delegate to a tag-along that wants to be helpful. The filters really build up crud over 2 weeks...that crud is no longer in the cabin. I found this unit at a discount and a name brand I recognize. There are others equally as effective but I only found this one that had washable filters there may be others I have not seen.



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