Dinghy winter storage

Discussion in 'Boat Design' started by laukejas, Sep 26, 2015.

  1. Jamie Kennedy
    Joined: Jun 2015
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    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    I like the idea of a coat of wax before winter storage. Maybe you could do the same now after removing the mildew as much as you can and drying the boat out as much as possible, maybe with a hairdryer on an otherwise very cold night, then wax it the next day before heading back in to the city. Tough storage conditions for sure. Maybe the expensive marine paint inside and out next time.
     
  2. laukejas
    Joined: Feb 2012
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    Location: Lithuania

    laukejas Senior Member

    Sadly, I don't speak German, but I'll try to translate it. What about fire? Surely a bulb won't cause any, as long as it is not touching anything?

    That sounds like a lot of work. Still, better than letting mildew eat my boat. As for marine paint... If only I was that rich :D
     
  3. Heimfried
    Joined: Apr 2015
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    Heimfried Senior Member

    in short:
    type 4 (for example) in the input box "t (Luft)",
    type 95 in the input box "rel. Feuchte in %"
    as shown here in the pic http://www.hygrothermik.de/index.php/arbeit-mit-dem-lueftungsrechner/eingabe
    Click button "absenden".
    The answer is shown here: http://www.hygrothermik.de/index.php/arbeit-mit-dem-lueftungsrechner/antwort

    The dew point is 3.3 °C. (The comma is decimal sign for output, but for input it is ok to use a point as decimal sign.)

    Click "Eingabe öffnen" at top of the next column. The input boxes move in this column.
    Type 7 for temperature and change input of humidity to "Taupunkt in °C" (click small Triangle) input 3.3, then click "absenden".

    The result of the calculation tells you, that in a garage with air of 4 °C and 95% RH, a boat which has a surface temperature of 7 °C will have only 77 % RH in the boundary layer of the surrounding air.

    You can change the 7 °C to 6 °C and see, that the RH is no longer under 80% and so on. (Don't forget button "absenden" after every input change).
     
  4. Heimfried
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    Location: Berlin, Germany

    Heimfried Senior Member

    double post instead of edit, sorry
     
  5. laukejas
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    laukejas Senior Member

    Thank you. That information is most useful. So, it appears that I have to raise hull temperature quite a lot to have RH below 80%. That calls for more and stronger bulbs... I'm not sure if that's even possible in garage full of holes for the wind to howl through.
     
  6. SaugatuckWB
    Joined: Jan 2014
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    Location: Saugatuck,MI

    SaugatuckWB Junior Member

    Too complicated

    I think you are complicating things way too much. You have very wide temperature swings and predicting the effects of various combinations of light bulbs to heat a boat to retard mold growth is impractical.

    The cure is to lower the moisture in the air in the garage. If it is a swampy area as you said the source is probably the ground. Create a vapor barrier and turn the boat right side up so its not a trap. If someone can explain the logic of turning the boat upside down please do.

    I work at a marina where we store 400+ boats in unheated damp and drafty sheds every winter with temps within your range (but very infrequently as cold as your lows). There are no heat sources allowed in the boats. All we do is cover them loosely with plastic (or not at all) and always leave some ports open for ventilation. No reported mold problems.
     
  7. Heimfried
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    Heimfried Senior Member

    The air density decreases, if air get warmer. The air around the bulb will therefore flow upwards but is trapped into the boat hull (if boat is turned upside down). If there is no disturbing wind which causes turbulences, inside of the boat hull thermic layers of air are generated, warming up the hull.
     
  8. Heimfried
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    Location: Berlin, Germany

    Heimfried Senior Member

    Hallo laukejas,

    I remember it is easier to use this sheet, because you need only one column:
    http://www.hygrothermik.de/rechner/feuchterechner8d.php

    Just fill in Temperature and RH of the air in the Garage, click "absenden" and one of the results, called "aw-08-Temperatur", shows you the temperature at which the RH of the boundary layer is 80% (aw = 0.8).
    Next row "Abstand zu aw-08" shows the temperature difference between aw-08-Temperatur and room temperature.

    Differences in temperature are given in Kelvin (K), which is scientificly correct. E.g.: 15 °C - 13 °C = 2 K . (If you prefer, call it °C.)
     
  9. Tiny Turnip
    Joined: Mar 2008
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    Tiny Turnip Senior Member

    Moisture prevention in buildings is a very complex issue. It sounds as if your boat is in very damp conditions, and sometimes very cold.

    Simply put (and forgive me if I am stating stuff you already know) but if air, carrying nearly as much water as it is able to carry at a given temperature, comes into contact with a surface at a colder temperature, the air will cool, and will not be able to carry as much moisture: the water is forced out of its vapour state (carried in the air) and will tend to condense on the cold surface.

    If the boat is at the same temperature or higher temperature than the surrounding air, then no condensation can happen.

    The lightbulb is an attempt to warm the boat to be higher temperature than the surrounding air, and in common storage conditions this should work. However, if you are in very damp and cold conditions, with a never ending supply of moisture entering the air from the damp floor or ground, then it is possible that the lightbulb will be doing more harm than good.

    It may be that supplying sufficient heat in this environment just is not viable economically.

    Its difficult to give advice without knowing the conditions exactly; however from what you have said, my inclination would be NOT to try to warm the boat; leave it at the same temperature as outside, sheltered in the garage, or outdoors under cover. Ventilate as much as possible. If security is not an issue, could the garage doors be left open? If the boat is tarp covered but outdoors on horses, then get as good a separation between the boat and the tarp as possible.

    By the way, I have heard it said that frost does more damage to varnished finishes than sunlight, if you have any varnished wood.

    Further, mould will grow without liquid water (i.e. in high humidity) and at low temperatures. I would consider spraying the boat with an anti mould and mildew spray before laying her up.
     
  10. SaugatuckWB
    Joined: Jan 2014
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    SaugatuckWB Junior Member

    I understand heated air rising and being trapped under the boat. That's obvious. It's also what I think is the problem.

    Mold is growing under the present conditions, so I'd recommend a change. Not just more of the same.

    Anyway, good luck.
     
  11. messabout
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    Location: Lakeland Fl USA

    messabout Senior Member

    Wikipedia article about mold spores:https://en.wikipedia.org/wiki/Mold

    There are zillion types of mold. Some sort of bacterium is the culprit. It seems that the growth of the spores is temperature dependent as well as moisture dependent. Lower temperatures retard the growth of some of the many types. Laukejas' plight is not uncommon.

    Inasmuch as temperature is a growth factor, maybe we should let the boat remain frigid without benefit of the heat provided by the light bulb. This is speculation but there may be some advantage in removing the heat source.

    In any case, I do not think that the growth of mold in a little boat like his is a serious problem. In the springtime a dose of mild chlorine scrubbing or TSP solution will almost surely remove the nasty mold and all its' evil cousins.

    I have been exposed to that sort of thing here in Florida where we have high humidity and moderately high temperatures. My little boat lives on its trailer in the back yard. Over time it will develop some blackish mold that I can dispatch with a bit of scrubbing with mild chemical solutions. Laukejas' mold is brownish, mine is black. I reckon that neither of them is a likely jugger naught that is going to eat my paint covered Occumee wood. Twelve years and counting....so far no problems except the annoyance of having to clean the boat. Even my shower stall gets some mold. It is usually pinkish. A dash of chlorine makes it go away in a matter of seconds. Observe that bathrooms and shower stall are both damp and warm. The absence of UV radiation in the bathroom may even have some influence. That may also factor into the case for Laukejas.
     

  12. cmckesson
    Joined: Jun 2008
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    cmckesson Naval Architect

    I have this problem in the winter inside my yacht, and my wife has a very simple solution: She wipes everything down with Ammonia, and nothing grows over the winter.

    The rags are soaked, anything left uncovered is wet, but at least we have no mildew.
     
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