How to stop the sweating

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  • January 10, 2013 11:32 AM
    Message # 1176805
      We just bought the Tyee, a WS32, and living in SE Alaska she has a big sweating problem thanks to the drastic differences between water and air temperature.  It has destroyed a lot of the plywood inside under previous owners and we are in the process of replacing it.  Now that we have access to the inner hull and bulwarks is there a preferred method of insulating her.  We have been thinking of a two part foam and filling the bulwarks and layering 3/4" thick everywhere else.  Heating her at dock seems to help, but not at the bulwarks.  Does anyone have any advice or has insulated their boat?  Any help is appreciated.
  • January 10, 2013 12:18 PM
    Reply # 1176846 on 1176805

    We were liveaboards here in Seattle for many years and encountered the same issues you are having.  At some point you will need access to the inside of your bulwarks so filling them with foam is not a good idea.  I pushed batts of fiberglass insulation up into our bulwarks, the act of installing the batts was a bit ichy, but it solved the problem.  I have recently seen small batts of fiberglass insulation at HomeDepot that are covered with plastic like a grocery bag, they would surely be less ichy to install and easy to remove!

    We also installed 1/4" closed cell foam under our cabintop overhead panels, under the trim panels below the decks and against the hull inside our lockers.  We ran 2 small ceramic heaters with fans to keep warm air moving around the boat.

    I never came up with a good solution to the condensation that sometimes dripped from the ports on cold nights.  Dang, thinking about it make's me miss living aboard, have you  noticed how the water tank only seems to go empty on really miserable rainy, windy nights?


  • January 10, 2013 2:35 PM
    Reply # 1176943 on 1176805

    Kevin, I have heard the fiberglass batt insulation stuffed into the bulwarks recommended before.  Other than the potential for itching, my bigger concern is about moisure wicking into the insulation.  I have seen many situations where fiberglass insulation get waterlogged in a residential home applications.  Did you experience any trouble with moist fiberglass insulation?

    I have noticed on our WS42 that there is significant condensation in the bulwarks just from the change in temperature day to night.  We are currently on the hard and have gutted the interior so that the only temperature differential is day/night.  I would like to insulate the bulwarks before I close up the interior.  I like the simplicity of the fiberglass batts, but I worry about waterlogging and mold.


  • January 10, 2013 5:28 PM
    Reply # 1177061 on 1176805
    Thanks Kevin.  I had been wondering if spraying foam was going to be a bigger problem in the end.  I have the same question though on the fiberglass batting.  Did it get waterlogged?  I have seen this many times in homes though mostly from leaks not condensation.
  • January 10, 2013 11:09 PM
    Reply # 1177246 on 1176805
    Deleted user
    Cheap and easy.  Buy Mylar food storage bags.  Buy styrofoam shipping peanuts.  Fill the bags and then iron shut.  That waterproofs the styrofoam in the mylar bags which are also reflective and very insulative as well as dirt and water resistant.  You can stuff them as they are very squishy and will conform to whatever shape you want.
  • January 11, 2013 6:56 AM
    Reply # 1177424 on 1176805
    Of course insulation will help, but you may be able to accomplish more mitigation with much less trouble and expense by improving ventilation.

    I use a solar-powered exhaust fan in my V-berth. I cut a hole in the lexan hatch cover to install it. It runs all the time.  It does a great job of removing moisture.

    For maximum effectiveness, use two solar fans, one forward, one aft, one exhaust one inlet.  That way you set up a circulation.   

    If you ride at anchor or moored, or you have a prevailing wind direction, point your dorade ventilator elbows toward the prevailing wind.  That's your inlet.  Then use solar fans for exhaust.

    Also, when you are not aboard the boat, leave all doors and drawers open to improve ventilation.
  • January 12, 2013 9:22 AM
    Reply # 1178196 on 1176805
    Deleted user
    A couple other tricks.

    Dehumidifier with drain hose to bilge and an automatic bilge pump. (This does at least 3 things.  It heats the cabin and reduces moisture which will raise the dew point and it has a powerful fan to circulate air.)

    Sun Pac Mildewcide---just remember to air the boat out and remove and place in a zip loc before breathing any air in the boat.  Hold your breath and put the bags in easy to gather locations while opening up and airing out.


    Air movement by any method.
  • January 13, 2013 8:58 AM
    Reply # 1178755 on 1176805
    Anonymous member (Administrator)

    I've been experimenting with insulation on Pygmalion W32 to solve the sweating inside the bullworks area and dripping into the cabinets and et al over time.

    Ran across at Home Depot some "Duct insulation".  It has a 1/8" thick closed cell foam with a aluminum foil backing in 1'X15' rolles for ~19.00.  The adhesive on the foam is quite sticky and the foil backing is shiny and form fitting.

    I've applied it to the cleaned surface of the bulworks about a month ago and yesterday was back at the boat to check on the results.

    What I found is that the area w/o the foam was noticably wetter (I could see the water on my hand)  then where the duct insultion was installed (it felt damp and cold).  One piece had fallen down so I dried it out and reapplied on top of another piece to make the total thickness ~1/4" and I'll check in a month or so.

    I think that the sweating seems to be worse on the sunny (south) side of the boat and above the water line. 

    If the sweating continues to be more of an issue - I've though about mounting 4 small computer fans on the trim piece of wood that hides the opening in the center of the cabin.  The fans should blow air up into the center cabin bulworks and out the aft and forward space, hopefully drying out the area.  What slows me down is the wiring, power needs etc.  see image below of the area I'm trying to describe.  The white paint is a new from Petite anti mildew paint.

    The 120V dehumidifier is another good idea.


    Same area with insulation applied

    I wish that I could use a 1/2" thick version of the same product.. I think that with a higher R rating this would work even better. 

    I'll advise in as more data comes in.


    PS I also though about the "pink" insulation for this area but had visions of glass particles dropping down and getting into everything - as well as absorbing moisture / water from leaks et al.


    Last modified: January 14, 2013 5:06 PM | Anonymous member (Administrator)
  • January 14, 2013 8:06 AM
    Reply # 1179418 on 1176805
    Deleted user
    If you want to go "All In" another trick is to get the 2 part LPU pour foam (1 or 2lb variety) and after mixing pour into plastic garbage bags.  As it expands take a piece of plywood to Mold the area to be insulated  After it drys you can shed the plastic skin and epoxy paint the foam for custom insulation blocks that are also mildew and waterproof should you seal and paint with an appropriate paint covering.  Now this is a ton of work but it is a great custom solution for problem areas.  The surface can even be made to be cosmetic by glassing and fairing the surface which shows.  The idea comes from building custom refrigerator boxes.

  • January 14, 2013 5:08 PM
    Reply # 1179941 on 1176805
    Anonymous member (Administrator)

    I've watched the "Holms on Homes" show and do envy the blue spray on foam they often use in garages voids -- but what a mess to apply post construction.


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