Solving Condensation, Dampness

Discussion in 'All Things Boats & Boating' started by Ultimate Design, Aug 20, 2015.

  1. Ultimate Design
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    Ultimate Design Ultimate Design

    I have a 19ft yacht that has no inside wall or ceiling to stop condensation or dampness so the condensation and dampness are bad,i was thinking of glueing foam matting on the walls and ceiling and i have seen this done with thin carpet material but has anyone here got experience so that i dont waste time and money finding out the hard way how to solve this problem?
     

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    Last edited: Aug 20, 2015
  2. rasorinc
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    rasorinc Senior Member

    Styrofoam flotation foam come in 1'"x 48" x 96" and gives you an R-5 insulation rating and epoxy can be used on it but will rot in direct sunlight. Also it will float 55 pounds in fresh water
    per cubic foot (1,728") salt water it is 62 pounds.
     
  3. JSL
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    JSL Senior Member

    Make sure the boat is well ventilated
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    You can buy some kind of mineral that soaks up moisture, in much the same way as silica gel works, presumably, cannot recall the name of it, but I have used it and it seemed to work OK in small confined spaces, not sure about this though. I just put it into old nylon stockings, and when it has absorbed as much as it can, just put it in an oven for a short time, spread out in a baking dish, and then it is ready to go again. Reddish-brown granular material.
     
  5. Ad Hoc
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    Ad Hoc Naval Architect

    JSL in post #3 gave you the correct solution. Prevention is better than cure.
    Interiors of boats must always be well ventilated.
     
  6. Ultimate Design
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    Ultimate Design Ultimate Design

    Thanks for the replies but i had a 21ft vivacity 650 (photo attached) that had plastic ceiling and walls and floor seperated from the outside fibreglass hull and i never had condensation dampness problems so the only solution im planning is rubber or foam matting glued to the fibreglass interior just like camping mats create a barrier between the cold ground and warm body.
     

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  7. SukiSolo
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    SukiSolo Senior Member

    Aaahh! so the Vivacity was well ventilated? AFAIK ventilation is the key and good pathways for air and drying stops too much condensation. Most FRP/GRP boats with the foamy linings do actually get a bit wet on the ceilings at least if people sleep onboard, or in rainy weather. The builders put the lining in to disguise this fact, you never see it in racing craft!. just push your fingers in hard to the lining first thing in the morning after sleeping inside for the night....
    However the material used is available so you could just fit this. I would not suggest carpet though as even marine carpet suffers quite badly unless really dried out.

    The better the thermal insulation of the hull material, the lower the condensation level. A cold moulded wood hull is better than a pure GRP one by a mile, and aluminium is terrible for thermal transfer, hence more condensation.
    Best to sort efficient ventilation by careful placement of vents and other orifices. Along with good drainage and limber holes, this helps to keep things at sensible levels.
     
  8. SamSam
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    SamSam Senior Member

    This always is curious when someone asks for advice, doesn't listen to it and does what he wanted to do to begin with.

    Try ventilation first. It costs you nothing. You'll quickly get tired crawling around in that little space trying to cut, fit and glue anything to the inside surface. It will probably not look good and possibly fall off before too long.
     
  9. Deering
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    Deering Senior Member

    Ventilation is clearly the best option as has been repeated above. But a viable backup solution might be to install a small dehumidifier with the water collection running overboard. I have a small greenhouse that suffered from condensation - that solved it completely.

    Depends on the availability of shore power, and how much time you spend parked at the dock. Obviously not a great solution if you are underway with limited power generation.
     
  10. SamSam
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    SamSam Senior Member

    A dehumidifier will dry it out quickly, you can dump it in the bilge if you have an automatic bilge pump. They have solar powered ventilators that work ok.

    I think if you have a problem with condensation, you usually get mildew. And if you put in carpet especially, you are liable to create a nice mildew/fungus/odor garden.
     

  11. JSL
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    JSL Senior Member

    A good read is the ' A Warm, Dry, Boat' by Roger McAfee.
     
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