Mold -- Is it as bad as they say?

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PNW Jeff

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Jun 14, 2017
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Hey Everyone,

My wife and I are serious about becoming live-aboards (we're in Seattle), and as part of the process we just spent 3 nights living on an older Grand Banks 42 to "test out" the space and the lifestyle. Overall, we LOVED the experience and it got us even more excited to find & purchase our perfect boat.

With that said, my #1 concern is mold. I've heard it can be pervasive on boats and very difficult to keep at bay, and my wife has mold allergies. She seemed to have some minor allergy reactions (primarily in the mornings) on the boat we just stayed on. Not sure if it was the bed, or just the boat in general.

Anyway, I've been doing a ton of reading on how to keep mold in check on a boat. From what I've read, keeping the boat heated to 70 degrees, running a dehumidifier to keep humidity under 50%, and allowing for proper ventilation (fans to move air and windows / hatches open when possible) seem to be the most common suggestions. All of which seem doable.

So, my questions to you all are...

1) Based on your experiences, is mold impossible to keep in check, or is it fairly easy if the proper measures are taken?

2) Does anyone here have allergies to mold and live on a boat without issue?

3) How difficult is it to keep mold clean in hard to reach areas? I'm not concerned about things like windows or areas with easy / obvious access. But, how does one deal with mold in more difficult areas to access?

4) Will a good survey typically be expected to look for and notate mold issues?

Thanks in advance for the answers and feedback!

Cheers,
- Jeff
 
Mold can form in some pretty inaccesible locations on a boat, so yes, for a person with allergies it could be bad.

Not sure what the common mildew is on a boat....so not sure whether that is a problem for her or not.

Living aboard in a temperate clime where fresh air is constamtly available could help, or strict environmental control aboard maybe.

But it is those hard to access spaces that may become an issue. My best suggestion is a garden sprayer with bleach or anti mold solution.
 
psneeld said:
Mold can form in some pretty inaccesible locations on a boat, so yes, for a person with allergies it could be bad.

Not sure what the common mildew is on a boat....so not sure whether that is a problem for her or not.

Living aboard in a temperate clime where fresh air is constamtly available could help, or strict environmental control aboard maybe.

But it is those hard to access spaces that may become an issue. My best suggestion is a garden sprayer with bleach or anti mold solution.
Click to expand...

Thanks for the feedback, I hadn't thought about a garden sprayer but that makes a lot of sense. Probably the best way to keep mold from growing in places like the bilge and any other less accessible places.

Something like this? Bare Ground 96 oz. 1 Shot N Gone Mold-Mildew Inhibiting Coating Pre-Loaded Into 1 Gal. Sprayer Applicator-BGMI-1F96 - The Home Depot
 
I keep aircon/heart running most days. Many ACs come with a cycle for controlling humidity. We are now on our third boat and have never had a problem with mold. Also, before storing the boat in humid climates, like Trinidad, my wife wipes down all surfaces with vinegar which helps keep mold at bay.

Gordon
 
Judicious use of an ozone generator can help kill mold....(ozone has risks to educate yourself on their use)
 
Jeff,

I'm glad you enjoyed the time on the boat!

Mold and mildew is an issues. I don't live aboard but have had boats in the Puget Sound area for a lot of years. Mold and mildew are actually more of a concern for a live aboard as just living on a boat increases the amount of moisture inside, particularly during the winter.

I have used dehumidifiers for years on the boat and they work wonders. The key is to keep them running continuously as well as fans that will circulate the air. The downside is that they are noisy. The other option is to use a Peltier type dehumidifier which is something that I have started to try this winter on my boat. I have three of the Eva-Dry dehumidifiers on my boat now that run 24/7. They do a good job, but not quite as effective as the larger compressor driven dehumidifiers. The good thing about the Peltier type is they work well in a warm boat, are small, and quiet.

Cleaning the boat is a bit part of prevention. Peggy Hall's book would be an important resource. The trick is to actually clean the areas that are hard to reach. Soap, water, and a long handled brush can go a long way to cleaning wet locker and bilge areas. Like psneed, I usually follow that with a 10% household bleach soln (ie dilute the household bleach with 9 parts water). This really helps a lot but you need to use the soap, water, and brush first.

Air circulation is important, but in the winter when it is almost 100% humidity outside, bringing outside air in is not helpful. This is where dehumidifiers work wonders.
 
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Wish I had a dollar everytime someone told me their boat didnt have mildew and after taking the back out of a closet and looking down between the hull and interior they choked.

No matter how much ozone, damaging to everything, or air conditioning or dehumidifying or whatever else is used to keep mildew at bay....
 
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Dehumidifier is the ticket. Better than running AC. In PNW you may still have issues on hull skin due to low water temps, but that should not cause an issue in a cabin kept dry.
 
Mold is a risk on boats. It's also a greater risk than most realize in their homes. A lot of times hidden mold. When you leave your home to go on a long vacation do you keep the A/C at the normal settings? Did the previous owners have a plumbing leak long ago?

With her problems, I'd definitely suggest testing for mold as an addition to the survey, using a professional service. Also, I'd suggest periodic testing on your own once you owned one. No, the typical survey would not detect all mold.

I would assume she has other allergies and I can imagine there are things about the boat and boating other than mold that could have set them off a bit. Anytime those of us with allergies move to a different environment, we're exposed to different allergens. Different trees, different pollen. Then of course the potential of exposure to improperly managed waste on a boat.

I found mold in an apartment I rented in college. I knew something was bothering me and eventually figured out it was coming from the closet. I then saw just a small bit of water damage on the bottom of a built in cabinet. I had it tested then went to the landlord. The moment they removed that cabinet it was obvious. There had been a plumbing leak and no one ever thought about the area behind or under the cabinet.

I would suggest some more trials to see. Also, think of other allergens that could be impacting her. She should have a feel for her allergies and will have to use that to help her figure it out. All the talk here about keeping the humidity in check to prevent mold and yet low humidity is an issue to me. A heated house in winter. I like living where there is no winter. Outside in a boat, I would expect some allergic reactions on her part if she has strong allergies. Hopefully, they're manageable. Mine are. I can do fine walking through a nice forest. On the other hand, I can't walk through an area planted with pine trees and I can't stay in a cedar log cabin and I most definitely can't go to an orange grove (oranges being my worst allergy of all). I'm ok in an arboretum, but not in a florist shop.

I think the mold should be manageable, but you may have to take steps others would not know they need to. I don't know what other allergies she has. I've learned to manage mine and avoid the worst. Hopefully she can do the same.
 
We had some original wall covering on our 30 year old boat. When removed, 60% of the area was mold.
 
I use a product called MX-3 that is mixed in paint, varnishes, and sealers. It "inhibits" mold, mildew and algae. It's clear and uses 1.5 oz./gallon. I use it in primers and final coats. Works in water, solvent and oil based products.
I have a 83' wood boat and have all my bilge areas power vented (low volume) that eliminates the "boat" smell and keeps enclosed areas dry. Something to remember, without venting, all cooking, shower, and breathing moisture stays in the boat when closed up in the winter and besides making good conditions for mold, etc., makes the boat uncomfortable, clothes and bedding damp, and so on.
Online at Amazon for about $14/7.5oz inc. Prime shipping (will do 5 gallons). Smaller and larger sizes are available.
 

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Lepke raises a good point. I've never owned a wooden boat so I don't know, but I would be hesitant to use a dehumidifier too aggressively on a wood boat. On my sailboats the dehumidifier would get the interior down to < 30% humidity. Not sure you would want it that low in a woody.
 
Greetings,
Mr. dh. Excellent comment. One might also have to consider copious amounts of wood trim/paneling in a FRP vessel as well.
 
I'm a full time liveaboard and have learned to battle the mold.

As everyone has said, cleanliness and ventilation are the key to keeping your boat mold free. Ventilation is so important. In addition to fans leave doors and drawers open when and where you can. Don't pack lockers and drawers full to the brim. For liveaboards mattresses are a big problem. They will grow all sorts of unpleasant things between the mattress and the berth flat. Use something to move air or provide a thermal break between the mattress and the berth flat. I've used stuff like this Interlocking Drainage Mats. I currently use a thin layer of closed cell foam between the mattress and berth flat. It's a little harder to find but works very well.

Turn your mattress often, unless it is an odd shape that can't be turned. Typically our boats will have more berths than liveaboards use on a daily basis. Those mattresses need air flow too, I just prop them up when not in use.

In the depths of a PNW winter you will fight humidity constantly. Some of the things I do are shower at the marina showers, really cuts down on humidity. Leave some windows cracked and the heat on when I go to work, I won't be there to mind the cold draft and it really dries the boat out. Move all the clothing I don't use during winter to a storage locker, less stuff in the boat's lockers and drawers means more air flow. If like mine, your mattress butts against the hull, pull it out a few inches during the day.

But sometimes it just gets away from you and you need to take drastic action.

Fiberglass is not a smooth glass like surface in the interior of a boat. It's almost as bad as wood or carpet for being a substrate for mold and mildew though it does not provide any 'food' for the fungus. So there you have it, our boats have at least 3 good ( bad? ) places for mold and mildew to thrive. The tendrils ( I'm probably using the wrong term here ) of the mold and mildew are deep out of sight. What we see are the fruiting bodies ( again, probably have the wrong term ). Clorox and vinegar will knock the fruiting bodies back, the mold / mildew seems to be gone only to reappear soon after clean up, a never ending battle.

Clorox and vinegar are a good first start, but now you need to get ready for the long term battle. Lepke recommends MX3 if you're repainting. I've used similar products with success.

If you don't want to repaint you need something that stays on the surface and inhibits the mold / mildew but is not toxic to you or your pets. I like to use Borax and not quite fully rinse the area. Leave some to dry on the surface. Here's a link to using Borax to kill mold. Does Borax Kill Mold?

Denatured alcohol has some effect on the mold as well. Hydrogen Peroxide is reputed to work but I've not tried it.

Years ago I lived in a rental with a serious mold problem. I never did win the battle but I beat it down to a tolerable level by

  • Washing with Clorox, rinse and let dry
  • Soak with vinegar, rinse and let dry
  • Soak with denatured alcohol, let it evaporate
  • Repeat for several days
  • Wash with Borax and let dry
It mostly worked.
 
My wife also suffers from allergies so I will add my three cents worth. She swears by hydrogen peroxide and white vinegar to clean and kill mold. Clorox makes her sick from the fumes and supposedly does not kill the mold, only bleaches it white.

Under our berth we put Hypervent Condensation Prevention Matting which we got from Defender. It allows air to circulate between the mattress and whatever it is laying on. In our case painted wood that forms the lid of the compartment where the water tank sits.

We also have diesel hydronic heat with forced air which helps to keep things dry. I am also on top of every little leak around windows etc to keep the interior as dry as possible.

It is doable but you have to stay on top of it.
 
Wwestman...thanks for the tip on bleach.

After some research, it definitely looks like bleach is really only a band aide.

:thumb:
 
Wow, thank you to everyone who chimed in (and keep the feedback coming if you have any!). This is massively helpful, and after reading the responses so far, I am encouraged to know that, so long as I am proactive and continuously taking measures to reduce and keep mold at bay, it should not be a deal breaker.

Again, thanks to all of you for the tremendous feedback on this, you guys (& gals?) have been such an awesome resource for me to bounce questions like this off of!

Cheers,
Jeff
 
The Hypervent Condensation prevention matting looks like a white version of a green version sold at Home Depot et al as a washable air conditioning filter. IMG_0896.jpg
 
Interesting discussion, I don't have a mould problem down in the caribbean. The boats wide open all day and the aircons on at night. One thing we found useful in my other prior retirement life were air scrubbers that ectronical chage the air etc. They pick up the mould and odors etc and deposit them on interior plates you wash of occasionally.

They are cheap to run basically the fan and some electronics and work well. Start on e in a room were people have been smoking and drinking beer, 12 hours later the rooms clean and has a slight metalic taste in the ozone.
 
PNW J,
Welcome to our NW boating world!

Mold is a fact of life for boats in these waters. Boat parts below/near waterline and on the north side can be in a condensing condition for extended periods without good ventilation and some heat. Advice offered in previous posts here is good.

My first thought is maybe hold off on a boat purchase until you've been through a few days of a winter type boating experience around here, when it is cold and damp.

I fight off mold through the winter by keeping the locker doors open, bunks/mattresses tilted up, heater on.

Before that I clean the lockers and boat spaces well then treat with a product called Moldex. It will kill the mold and the hyphae that grow into the boat. Bleach cannot do that. Bleach only works at the surface. Be careful with Moldex and follow directions, it is real chemistry to kill mold.

I've advised a couple other TF's here on this and seemed to work out OK.

I learned about mold the hard way cleaning up after Mexican hurricane floods at my winter place. Can't advise that plan!

Good luck on your boat search, see you out on the water somewhere!
 
GoneFarrell said:
Before that I clean the lockers and boat spaces well then treat with a product called Moldex. It will kill the mold and the hyphae that grow into the boat. Bleach cannot do that. Bleach only works at the surface. Be careful with Moldex and follow directions, it is real chemistry to kill mold.

I've advised a couple other TF's here on this and seemed to work out OK.
Click to expand...

Thank you all for the tip on bleach and its ineffectiveness on mold. I'll check out this Moldex.
 
Two good (older) friends who believed they were both suffering from dementia / Alzheimer's were a recently informed that they both had been exposed to black mold in their home. Apparently, while it may not be only cause of their condition, it is now recognized that black mold does cause memory loss and cognitive problems in those exposed over time.
 
I have an Auto A/C repair shop and mold & mildew is a common problem in cars here in Florida. Also produces musty smell!
When we bought our current boat it was stored under cover but without A/C running.
Had a considerable amount of mold!
Wife used a culture tray (the kind you send in for analysis), it came back with every kind of fungus and mold known to man.
Cleaned the inside with vintager solution and then used this Mist Service we have had good luck with in cars.
Did another test and Viola no more critters!
Here is a link to the web site

TerraClean

Now fortunately I have the machine, but if you have a problem to solve, I highly recommend it. Ozone generators can cause damage to rubber (like engine hoses. No bueno) probably worth the cost
 
Portage_Bay said:
I'm a full time liveaboard and have learned to battle the mold.

As everyone has said, cleanliness and ventilation are the key to keeping your boat mold free. Ventilation is so important. In addition to fans leave doors and drawers open when and where you can. Don't pack lockers and drawers full to the brim. For liveaboards mattresses are a big problem. They will grow all sorts of unpleasant things between the mattress and the berth flat. Use something to move air or provide a thermal break between the mattress and the berth flat. I've used stuff like this Interlocking Drainage Mats. I currently use a thin layer of closed cell foam between the mattress and berth flat. It's a little harder to find but works very well.

Turn your mattress often, unless it is an odd shape that can't be turned. Typically our boats will have more berths than liveaboards use on a daily basis. Those mattresses need air flow too, I just prop them up when not in use.

In the depths of a PNW winter you will fight humidity constantly. Some of the things I do are shower at the marina showers, really cuts down on humidity. Leave some windows cracked and the heat on when I go to work, I won't be there to mind the cold draft and it really dries the boat out. Move all the clothing I don't use during winter to a storage locker, less stuff in the boat's lockers and drawers means more air flow. If like mine, your mattress butts against the hull, pull it out a few inches during the day.

But sometimes it just gets away from you and you need to take drastic action.

Fiberglass is not a smooth glass like surface in the interior of a boat. It's almost as bad as wood or carpet for being a substrate for mold and mildew though it does not provide any 'food' for the fungus. So there you have it, our boats have at least 3 good ( bad? ) places for mold and mildew to thrive. The tendrils ( I'm probably using the wrong term here ) of the mold and mildew are deep out of sight. What we see are the fruiting bodies ( again, probably have the wrong term ). Clorox and vinegar will knock the fruiting bodies back, the mold / mildew seems to be gone only to reappear soon after clean up, a never ending battle.

Clorox and vinegar are a good first start, but now you need to get ready for the long term battle. Lepke recommends MX3 if you're repainting. I've used similar products with success.

If you don't want to repaint you need something that stays on the surface and inhibits the mold / mildew but is not toxic to you or your pets. I like to use Borax and not quite fully rinse the area. Leave some to dry on the surface. Here's a link to using Borax to kill mold. Does Borax Kill Mold?

Denatured alcohol has some effect on the mold as well. Hydrogen Peroxide is reputed to work but I've not tried it.

Years ago I lived in a rental with a serious mold problem. I never did win the battle but I beat it down to a tolerable level by

  • Washing with Clorox, rinse and let dry
  • Soak with vinegar, rinse and let dry
  • Soak with denatured alcohol, let it evaporate
  • Repeat for several days
  • Wash with Borax and let dry
It mostly worked.
Click to expand...

Portage:

Your post was a world of info. Thank you for sharing.:thumb:


Cheers

H.
 
"Judicious use of an ozone generator can help kill mold....(ozone has risks to educate yourself on their use)"

For NON livea board times , boats in FL in storage will mix up a wine bottle of WWI mustard gas chemicals. There under your galley sink,

Ventilate on return big time.
 
Bleach

I have not read any new info on effectiveness of bleach on mold. But when I was helping down on the coast after Katrina I was told by several 'pros' that pure bleach was useless on mold - causes the mold cells to go into shock and they stop taking liquids across the membrane. But if you apply a 10-15% bleach/water mix, that is weak enough not to cause shock and will cross the mold's membrane, but still strong enough to kill the cells. Works whenever I find mold or mildew in any of my rental units.:thumb:
 
I would love to see a tech paper on bleach and mold versus a lot of third hand info.

My guess is full strength or partial bleach is equally effective, whether good or not I cant say and other stuff might be much better.

Like drinking 1 gallon of Jack Daniels or 4...both are probably going to do you in.

I will say a spray bottle of diluted bleach has helped a lot on my 3 liveaboards...but hope I can find something better that doesnt ruin some fabrics.
 
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I've used Moldex as well on a stubborn locker. Killed it and used some of the preventer stuff, and it never came back. Doesn't smell like bleach, more like an old school dentist office.
 
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