Mold on wood/cushions - clean or replace? - SailNet Community
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post #1 of 16 Old 02-12-2019 Thread Starter
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Mold on wood/cushions - clean or replace?

Hey folks!

Been raining a lot this month and with the temperatures in the low and nearing 0ºC, a lot of condensation happened in my boat. Compounded with the fact that I probably have a portlight leak, and we were away for said month, there's quite a bit of mold on the portside settees and cabinet of our cabin. It looks pretty nasty!

We're new boat owners so not quite sure what to do about the situation. Here's our battle plan:
  1. Identify and fix the leaks. I'll at a minimum replace all the gaskets on the portlights and hatches because they're not closing well/dirty. Then I plan on pressurizing the interior with air and washing the deck with soapy water to try and identify bubbles from a leak. I'm thinking of probably rebeding all the portlights and hatches.
  2. Bring a portable dehumidifier. The boat stays closed for days/weeks between our uses (especially with the winter weather). I'll run a dehumidifier to try to remove/reduce condensation, and let the run-off go into the bilge for the bilge pump to clear.
  3. Treat the mold. This is where I'm not sure how to handle this.

Treating the mold.

I'm thinking of two ways:
  1. Disinfect and clean; or,
  2. Dismantle, throw away and replace.
Approach (1) is surely the most economical, but I wonder if it is feasible given what looks like pretty big infection. Can i sufficiently clean the wood? How about the cushion foam? The cushion covers? I've attached a video of the disaster. It seems pretty bad to me, but maybe it's not that bad to people with more boating experience? My default knee-jerk reaction was to (2) dismantle/throw away/replace, but my wife thought there's got to be a way to clean this. I thought she's probably right (she usually is).
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Re: Mold on wood/cushions - clean or replace?

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Re: Mold on wood/cushions - clean or replace?

Mold: bleach is your best friend. Use it.

Settee covers. Go check the price of re-covering them.... Now rip them off and wash them in bleach.

Portlights: there's nothing wrong with them. Clean the gaskets and bleach them.

Niw we've fixed up your boat... Oh, did I mention bleach?

Just plain bleach, nothing fancy. Any additive can stain but bleach is fine.

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Re: Mold on wood/cushions - clean or replace?

It's a boat. All boats eventually have leaks. The trick is staying ahead of them.

Portlight Gaskets - Check them for serious cracking (not light surface cracks). If they're not cracked they're salvageable. Clean them GENTLY with Dawn dish soap and warm water until you get all the dirt out of the seals and off the portlight. Now rub Vaseline into the gaskets. It will soften and swell them and they'll seal up tight again.

Google cleaning moldy cushions. There are a lot of options. The best one depends on the type of fabric, but if they're seriouly moldy I'd consider replacement.

Once you've got all the mold out of the boat put a couple of open containers of Kanberra Gel and Damp Rid in the boat for a week. The Kanberra Gel will kill the mold spores, the damp rid will suck up the humidity. Kanberra is expensive but it works wonders. I always keep three open containers of it on board.

Consider adding a solar fan to keep the air moving in the boat when you're not there. Make sure you bilge pump is working. Keeping the bilge completely dry will depend on the type of shaft seal you have.
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Re: Mold on wood/cushions - clean or replace?

Mark's not wrong about the bleach.

I've used this stuff:

Not as harsh as bleach, smells nicer. Spray it in the bilge, in the lockers and hard to get to places just in case. Won't make things change color like the bleach does (except the dead mold).

Once you're all cleaned up. Find a way to keep the air moving in the boat, solar or shore powered fan will help a lot. Mold doesn't like airflow.
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Re: Mold on wood/cushions - clean or replace?

For wood you can use Old English Oil, Pledge, or similar products in liberal amounts. Bleach might stain the wood and your fabric, so you need to experiment with that approach. Keeping the boat warm and dry is best. Dehumidifier is a great approach but they can easily pull a gallon of water out of the air in 12 hours so make sure your drainage works, or the thing will just shut down when full. And don't be too afraid of mold. We evolved breathing in that stuff.

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Re: Mold on wood/cushions - clean or replace?

Bleach may work on surfaces you can reach however to erradicate it for good you must take a " bombing" approach after the bleach cleaning. Biocide or Concrobium.

After a clean bill of health I am a big Kanaberra fan

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post #8 of 16 Old 02-13-2019
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Re: Mold on wood/cushions - clean or replace?

Practical Sailor and Good Old Boat magazines both have good recent articles (by the same author) on eliminating and preventing mold using combinations of borax, washing soda and TSP that work identically to commercial products like concrobium etc, and cost much less. (try this link, or search for 'mold' on the PS website:

I've used them and they work well. If you have a boat and don't have access to those resources, subscribe with the money you save by making your own cleaning formulas.
I've read mixed opinions on using bleach, though it does kill mold. Borax kills it too, and residual borax prevents its return.
Or you can buy all new stuff and clean the mold off of that in another few months, especially if you don't find away to keep your interior ventilated.
Pressurizing the interior and looking for bubbles sounds inventive but I would think you'd need an unhealthy or impractical level of air pressure for it to produce bubbles. Try crawling around every place you can access while it's raining heavily, or while someone is on deck spraying a strong stream of water with a hose. You can also spread talcum powder around the inside of the hull and watch for water trails after a rain or hose-down. You might find some online resources that pertain to your boat where you can learn where the common leaky spots are. Or check around anyplace that hardware penetrates the deck or hull, and the joint where the deck and hull meet.
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Last edited by svselkie02; 02-13-2019 at 06:43 PM.
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post #9 of 16 Old 02-19-2019 Thread Starter
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Re: Mold on wood/cushions - clean or replace?

Thanks all for your answers! For the mold, I've been spraying a bleach mix on it for now with a spray bottle. Haven't got around to cleaning the surface just yet, I've been focusing on plugging the leaks. I came back when it was raining and have found 3 definite sources for the leaking, and 2 probable others.
  • Portlight seal on the video I linked was not sealing properly. I cleaned it but it was still leaking. I removed the old one, cleaned the old sealant and put it with a new seal (and new o-rings on the handles) yesterday. We'll see how this worked.
  • Hatch handle on one of the flush deck hatches is loose and leaking through the bolt which is slightly corroded. I'm planning on removing the handle, changing the bolt (and o-rings if there's any) and adding some silicon grease in the hole. Hopefully that'll do it.
  • A hole from an old diesel heater which is leaking. I'm not sure what to do about this one, either permanently patching it with fiberglass or cleaning up the hole and using it to put a solar vent. I made a separate post about this one.

The 2 other probable sources:
  • I saw water seeping out of the hole where the mast's wire harness come in. It's a deck stepped mast. Is there a way to stop this leak without taking the mast off? At least until I come around to needing to take the mast off.
  • I think some of the deck hardware is leaking a bit, probably at least at the chainplates? I'll try to rebed everything this week, but I'm not sure how to handle rebeding the chainplates. I haven't done any of this before, but I've been following the instructions in Don Casey's book on the subject.
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Last edited by aybabtme; 02-19-2019 at 11:41 AM.
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post #10 of 16 Old 02-22-2019
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Re: Mold on wood/cushions - clean or replace?

Vaseline (petroleum grease) on rubber is a bad idea. Petrochemicals eat rubber, they break it down. That's why they "soften" it and "swell" it, that's the rubber breaking down. Better to use synthetics that are designed to replace missing volatiles and preserve the rubber (or other elastomer). FWIW.
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