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Vapor barrier under berths

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Vapor barrier under berths

Post by StValentine » Wed Apr 17, 2019 8:54 pm

Mildew is a constant battle on a boat, especially an old one like mine. I'm thinking about putting a plastic vapor barrier underneath each berth to keep the moisture from the bilge away from the mattresses and the drawers underneath the bunks. Can anyone think of why this wouldn't be a good idea? I don't want to do it if it's going to cause other unforeseen problems.

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Re: Vapor barrier under berths

Post by homeiste » Sun Apr 21, 2019 5:56 am

Since no one else offered up thoughts, I'll do so, with the caveat that I've never owned a boat with a cabin/berths. Putting a vapor barrier like plastic anywhere is providing a spot for moisture to condense to liquid water when temperatures differ between sides of the barrier. I propose this would be the situation with a cabin on one side of the barrier and bilge on the other. So I would ask myself where that newly formed liquid water will end up after it condenses on the plastic. Cushions or wood would be bad, leading to more mildew , mold, and rot. My solution would be to enhance air circulation through the cabin/berth area and bilge to remove stagnant damp air as a way to reduce mildew formation. When not in use, position cushions to maximize airflow through and around them, open cabinet doors, locker areas, etc.
1960 18' Continental
1970 Boston Whaler Sakonnet w/ Bearcat 55 outboard

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Re: Vapor barrier under berths

Post by tkhersom » Mon Apr 22, 2019 4:36 am

I also think a vapor barrier is going to cause more problems than it will solve in the long run.

In the south people run their air conditioner to reduce moisture in their cruisers. Living in the north and being on a mooring where I am not hooked up to electricity I use DampRid products. I have had the best luck with the smaller refillable canisters.
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1957 CC 21' Continental "Yorktown" (Mom's boat)
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Re: Vapor barrier under berths

Post by StValentine » Fri Jun 07, 2019 9:05 pm

Thanks. I opted not to do the vapor barrier and got the AC fixed. Much more comfortable and a lot less humidity.

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