• 9th November 2007 - By adventuresofgreg

    This is very important – adequate ventilation.

    One of the reasons Rick Willoughby designed WiTHiN as a water tight capsule is to protect me from the harsh ocean environment. This includes exposure to the sun and skin-corrosive salt water.

    WiTHiN will be painted with a reflective color to minimize solar heating, and we kept the number and sizes of windows down to a minimum to also mitigate that heating effect. I will be producing plenty of heat while pedalling, so I really need some efficient way of circulating the hot inside air out, and replacing it with outside fresh air.

    I have installed two dorade vents which automatically close when dumped with water, and are designed to allow water to run out without entering the cabin. The ducts can be oriented to point toward a headwind and the idea is to point one into the wind for fresh air intake and one of them with the wind for ventilation.

    To facilitate efficient air movement, I installed a .3 amp 12 vdc computer fan over one of the vents and it blew (I mean it sucked). Way to little power. So, I got on the phone and sourced a 1 amp fan by Circuit-Test. I made a Sintra plastic shroud for this fan to fit over one of the dorade vents and ran a test to see just how much more efficient this 1 amp fan was in circulating air than just allowing the vents to do it. My battery is good for 50 amp hours, so about 50 hours running the fan on a full battery charge (not including other electronic loads like music, gps, etc).

    I put my heat gun into WiTHiN, closed the hatch, left the vents open and heating the interior up to 25 degrees C. The room temperature at the time was 19 degrees C. Then I timed how long it took for the interior temperature to drop back to 22 degrees. It took 29 minutes.

    Then, I repeated the test with the fan on. It took 11 minutes to cool from 25 degrees to 22 degrees compared to 29 minutes without the fan.

    I noticed that the volume of air being blown by this fan was much greater when it was not placed on the shroud over the vent. This is probably due to the small air in-take area of the vent itself restricting air flow through the fan. I repeated the test with the fan blowing freely inside WiTHiN just sitting on the floor, and it took 25 minutes to cool from 25 degrees to 22 degrees. This might seem obvious to some of you, but I wanted to know for sure that my fan was going to work as I had planned.

    I mounted the fan and shroud using dual-lock (like Velcro) so that the fan can be moved to the dorade vent on the other side, or somewhere else inside WiTHiN. I also used the snap-loc because there is a latch on the vent to manually close it. I need to have emergency access to this in case the automatic shut off doesn’t work.

  • No Responses to “Venting some important stuff”

    • Klaas on November 12, 2007

      Ehrr.. ehmmm….

      Your boat is floating in the ocean. water can cool things quite efficiently. Shouldn't you test the cooling rate in a lake or so?


    • Marc from France on November 12, 2007

      Greg, I did install this same type of vents on diffĂ©rent boats: they are not fully watertight! and sure not so close from the water and vertical…

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