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Hammock Camping Re: Oh Boy, Cold Wars II, winding up!

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  • o123david
    ... We are saying the same thing in different ways. We totally agree. ... Yes, we create a bubble of heat in all directions, even beyond the region insulated
    Message 1 of 57 , Sep 2, 2003
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      >Wind does not add cold, it removes heat. And it does not have to
      >blow into the insulation to do this, it only has to remove the layer
      >of air that was warmed up by the insulation that your body warmed up.

      We are saying the same thing in different ways. We totally agree.

      >You are in effect generating your own bubble of heat. this bubble
      >actually extends several inches below your hammock into the night
      >air, even with a very good pad.

      Yes, we create a bubble of heat in all directions, even beyond the
      region insulated with a pad. But the heat dissipates into the air
      more quickly than it would into dry ground, and therefore we need
      more insulation below us (thicker pads) than we need with the same
      weather conditions when sleeping on dry ground. We do not, however,
      need thicker sleeping bags.

      >If you were to put a windproof silnylon barrier right up against
      >that closed cell pad that was losing heat, it would make only a very
      >minor difference in your warmth. On the other hand, blocking the
      >wind from penetrating a down garment would make quite a difference
      >in how warm it will keep you.

      According to Newton's Law of Cooling the heat transfer is equal to
      the thermal conductivity of the material times the cross-sectional
      area times the temperature difference between the two boundaries
      divided by the thickness of the material.
      The part of this equation that seems relevant is that the rate of
      heat loss is proportional to the thickness of the insulation between
      the person and the point within the insulation where the temperature
      is approximately what it is outside of the insulation.
      The actual situation is, of course, more complicated. I have, for
      instance, ignored the effect of any clothing the person might be
      wearing.

      It appears to me that what happens is that without wind you have to
      go all the way through the insulation to reach the point where the
      temperature is the same as what you find outside the insulation. If
      there is wind then you only have to go part way through the
      insulation to reach the point where the temperature is similar to
      what you find outside the insulation.
      This is true no matter what the insulation.
      And this is, of course, an approximation.

      Therefore, if the insulation is down, and if the wind is strong
      enough to have the temperature halfway through the down be similar to
      what it is outside of the down, then you have lost half of the
      insulating value of the down. If the insulation is closed cell foam,
      and the wind is strong enough to have the temperature halfway through
      the closed cell foam be similar to what it is outside of the closed
      cell foam, then you have lost half of the insulating value of the
      closed cell foam.
      And if in either case you place a wind-proof layer outside of the
      insulation then you will regain the half of the insulating value that
      had been lost to the wind.

      >The goal of your windproofing efforts should be to keep the wind as
      >far from your insulation as possible, not just to keep it out of
      >your insulation. The advantage to the skirt and cone ideas is that
      >they protect the outer air layer of your heat bubble.

      Because of convection if doesn't matter how far away you keep the
      cold wind as long as you have the same thickness of the same
      insulation in the area protected from the wind.
      Again, this is an approximation.

      >As for the condensation issues... You need convection, but the
      >source of the air does not necessarily have to come through the
      >fabric.

      From what I have read about the "chimney effect" and tent design it
      is necessary to a have a source of cool dry air below and a vent
      above where the warm moist air can exit.
      I was hoping to find that if was possible to have a windproof hammock
      with a large open area above and avoid the condensation problem. It
      appears that this only works if the hammock is somewhat windproof.
      Therefore it appears that fresh air must come from below and through
      the fabric of the hammock.

      >I think your experiments are leading in the right direction.

      Thank you.
      I described what I have done in earlier messages and hope that others
      will experiment as well. --David
    • Thomas Peltier
      Looks very nice. _____ From: Chet Clocksin [mailto:cclocksin@buckeye-express.com] Sent: Friday, September 12, 2003 5:55 AM To: hammockcamping@yahoogroups.com I
      Message 57 of 57 , Sep 12, 2003
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        Looks very nice.

         

         


        From: Chet Clocksin [mailto:cclocksin@...]
        Sent: Friday, September 12, 2003 5:55 AM
        To: hammockcamping@yahoogroups.com

         

        I just posted another photo in "chet's home made" folder (I also deleted a few) Take a look at the last photo in the folder. A dog could be very cozy in there, and provide some additional heat. This set-up should also be a true storm proof set-up simply by closing the "doors" at the bottom.

         

        Chet

        -----Original Message-----
        From: chcoa [mailto:jdeben@...]
        Sent: Friday, September 12, 2003 2:25 AM
        To: hammockcamping@yahoogroups.com
        Subject: Hammock Camping Oh Boy, Cold Wars II, Doggie heater

        The ground in more what I was thinking for several reasons, material
        strength, warmth, etc.. but you are right they could hang a little
        too.  My only concern with this idea is that in the night if for some
        weird reason the hammock malfunctioned and I fell on her.  I wouldn't
        want to do that of course!  ACK!

        jamie in az

        --- In hammockcamping@yahoogroups.com, "Ray Garlington"
        <rgarling@y...> wrote:

        > This is a really good idea.  An open-bottom cone could be staked to
        > the ground with a side entry hole for the dog.  He would have a
        nice
        > house separate from your sleeping quarters & he could contribute
        some
        > heat.  Much better than tenting with a wet dog!
        >
        > If the dog was 'hammock trained', you could have a closed-bottom
        cone
        > with a side entry for the dog.  He would then be suspended above
        the
        > ground.



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