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Re: Hammock Camping Bottom Almost Quilt for HH...

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  • geoflyfisher <geoflyfisher@yahoo.com>
    Very well said as always! I think the improvement made by the insulation is in the break-up of convection currents without adding conduction paths. I m with
    Message 1 of 20 , Feb 5, 2003
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      Very well said as always! I think the improvement made by the
      insulation is in the break-up of convection currents without adding
      conduction paths. I'm with Sgt ROCK in believing that it is very
      hard to break out the effects of vapor barrier vs reflection on the
      shiny fabrics/materials.

      Yes, I had never seen an adequate description of the Clark Hammock,
      but after I did the patent search on the Hennessy hammock, I just
      went searching for hammock and tarp. The Clark patent came up and I
      see from the drawings how the pockets would work just like the idea I
      posted (and is listed in the patent as doing so). It is certainly
      not the first time I have had an idea and found out that it has
      already been patented!!

      I look forward to getting your book in the mail tomorrow Ed. I look
      forward to trying out the new hammock this afternoon. I look forward
      to all the experiments everyone is doing with the cold.

      Rick aka Flyfisher

      --- In hammockcamping@yahoogroups.com, "Ed Speer" <info@s...> wrote:
      > While I haven't tried exactly what you're suggesting Flyfisher, I
      have
      > noticed that any dead air space is better than none at all. Of
      course
      > the smaller the dead air spaces in an insulating thickness, the
      slower
      > the overall heat loss and the better it works. For instance
      skirting
      > around a moble home works wonders keeping out cold wind; thus the
      house
      > is warmer and heating bills are lower. However, my limited
      experience
      > with large dead air spaces beheath my hammock is that they are
      > significantly colder than filling those spaces with insulation. In
      fact
      > it is often warmer to eliminate the large dead air space and
      relpace it
      > with a much thiner insulation. For instance, when my PeaPod
      sleeping
      > bag is kept open on the top, it can sag below the bottom of the
      hammock
      > and create a large dead air space there (6-10" deep). It can be
      > significantly warmer on my bottom to tuck up the PeaPod to
      elmininate
      > this dead air space and bring the 0.8"-thick PeaPod insulation
      right up
      > to the bottom of the hammock.
      >
      > The Clark Jungle Hammock, a very adequate camping hammock, has 6
      large
      > gear pockets beneath the hammock fabric. The pocket fabric is the
      same
      > non-breathable fabric as the hammock. Filling the pockets with
      gear,
      > clothes, leaves, etc. creates a bottom insulation similar to your
      ideas
      > (and others posted previously on this List). While the bottom
      pockets
      > are handy, they must be fully stuffed with gear or clothes to
      provide
      > adquate insulation in cool weather; I found that only overstuffing
      them
      > with leaves worked in below freezing temps. Thus, in cold temps,
      the
      > bottom pockets worked best when large dead air spaces were replaced
      with
      > tiny dead air spaces.
      >
      > The double-bottom idea you mentioned is employed in several hammock
      > models--but I suspect, it's still necessary to add proper
      insulation in
      > cold conditions.
      >
      > Dead air space is the best insulation---it just takes a hell of a
      lot of
      > them to be warm! But even a sleeping bag which has millions of
      dead air
      > spaces does not stop heat loss--it only slows it down long enough
      for
      > one to get a good night's sleep. If you have too few dead air
      spaces
      > around you, the heat loss is too fast.
      >
      > The various systems most folks are describing on this List employ a
      > combination of items, such as 1) one or more wind blocking fabrics
      to
      > create a large dead air space, and 2) one or more insulation layers
      > consisting of millions of tiny dead air spaces. Some of us also
      emply a
      > radiant heat reflector fabric...Ed
      >
      >
      >
      > Ed's use of leaves between the hammock and the pea pod bottom
      started
      > me thinking of other ways to have a breathable dead air space. I
      > began to think of carrying just a nylon shell which velcros to the
      > bottom of the hammock and which could be stuffed with dry leaves.
      >
      > But what if there are no dry leaves? Well, clothes could work in
      the
      > space under the hammock... or rain gear, or rucksack.
      >
      > But if that works, why not just the nylon shell alone hanging a
      > couple inches below the hammock - or perhaps two layers which are
      not
      > quite the same size, so they hang away from each other. How about
      > sewing "tubes" which self inflate because the bottom cross-section
      of
      > the the tube is a little longer than the top of the tube and the
      > bottom hangs down a bit more?
      >
      > True, there will be convection currents in the air filled spaces
      > which will not work quite as well as space filled with down or
      other
      > insulation... but it might be quite good enough for most cases.
      >
      > Rick aka Flyfisher <><
      >
      >
      >
      > Yahoo! Groups Sponsor
      >
      >
      > <http://us.adserver.yahoo.com/l?
      M=237194.2927557.4274366.2848452/D=egrou
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    • tcoug7 <tcoug7@aol.com>
      I look forward to all the experiments everyone is doing with the cold. GGGGGoooodddd tttttooo haaaaave youuuu alllloonnnnnng - ;) Tim
      Message 2 of 20 , Feb 5, 2003
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        <snip>
        I look forward to all the experiments everyone is doing with the
        cold.


        GGGGGoooodddd tttttooo haaaaave youuuu alllloonnnnnng - ;)

        Tim
      • tcoug7 <tcoug7@aol.com>
        ... That s true, but as you know, heat is transferred by either conduction, convection or radiation. Actually in our instance, by all three simutaneously.
        Message 3 of 20 , Feb 5, 2003
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          --- In hammockcamping@yahoogroups.com, "geoflyfisher
          <geoflyfisher@y...>" <geoflyfisher@y...> wrote:
          > Very well said as always! I think the improvement made by the
          > insulation is in the break-up of convection currents without adding
          > conduction paths.

          That's true, but as you know, heat is transferred by either
          conduction, convection or radiation. Actually in our instance, by
          all three simutaneously. But, by creating millions of 'cells' of
          dead air space, each one becomes more stable with regards to dynamic
          changes. The overall effect on a macroscopic view is an insulating
          layer. But, on a microscopic view, each little cell is doing it's
          own thing. Just like the fiberglass insulation in you house walls.
          If it was just to create a dead air space, then there would be no
          need for the 'pain-in-the-a@#-to-install' stuff. Rather, by creating
          millions of little dead air spaces, a much more stable layer is
          created - which translates into much greater resistance to changein
          temperature.

          PS - I'm for the vapor layer. Radiant heat loss is real. It may be
          least important, but we are really trying to capture all heat that's
          available - so we sleep better. In my tests, I feel it's made a
          difference.
        • debweisenstein <dweisens@aer.com>
          Ed, what about an easy modification of the PeaPod to add mitten hooks or toggles to the inside of the Peapod along the edges of the hammock so that the PeaPod
          Message 4 of 20 , Feb 6, 2003
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            Ed, what about an easy modification of the PeaPod to add mitten
            hooks or toggles to the inside of the Peapod along the edges of the
            hammock so that the PeaPod could be left open but attached to the
            hammock in a way that it couldn't sag. This would mimick the
            underquilts people are designing for the Hennessey and provide
            more flexibility. Also, do you ever keep the PeaPod attached to
            your hammock and stuff the whole thing together? Or roll up the
            hammock with foam pad inside?

            --- In hammockcamping@yahoogroups.com, "Ed Speer" <info@s...> wrote:
            > However, my limited experience
            > with large dead air spaces beheath my hammock is that they are
            > significantly colder than filling those spaces with insulation. In fact
            > it is often warmer to eliminate the large dead air space and relpace it
            > with a much thiner insulation. For instance, when my PeaPod sleeping
            > bag is kept open on the top, it can sag below the bottom of the hammock
            > and create a large dead air space there (6-10" deep). It can be
            > significantly warmer on my bottom to tuck up the PeaPod to elmininate
            > this dead air space and bring the 0.8"-thick PeaPod insulation right up
            > to the bottom of the hammock.
            >

            >
            > Yahoo! Groups Sponsor
            >
            >
            > <http://us.adserver.yahoo.com/l?M=237194.2927557.4274366.2848452/D=egrou
            > pmail/S=:HM/A=1437215/rand=515177716>
          • Ed Speer
            Good thinking Deb, but one can easily position the PeaPod the prevent this sag. Since the PeaPod and my hammock both have Velcro along the long edges, the
            Message 5 of 20 , Feb 6, 2003
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              Good thinking Deb, but one can easily position the PeaPod the prevent this sag.  Since the PeaPod and my hammock both have Velcro along the long edges, the PeaPod can be Velcroed to one edge of the hammock and the other edge can be tucked inside the hammock far enought to eliminate the unwanted air space bleow.  Of course when the PePod is fully wrapped around the hammock, there is no botom sag anyway.
               
              And yes, I often keep the PeaPod and hammock together and stuff them together into my pack.  On a recent trip, my partner used the Moonbow Gearskin pack which easily allowed him to stuff the PeaPod, hammock, sleep pads, and sleeping bag all together into the pack at the same time--it was very simple and took only 1-2 minutes from take down to be fully packed!  Sure beats stuffing gear into tiny stuff bags on cold mornings!...Ed
              Ed, what about an easy modification of the PeaPod to add mitten
              hooks or toggles to the inside of the Peapod along the edges of the
              hammock so that the PeaPod could be left open but attached to the
              hammock in a way that it couldn't sag.  This would mimick the
              underquilts people are designing for the Hennessey and provide
              more flexibility.  Also, do you ever keep the PeaPod attached to
              your hammock and stuff the whole thing together?  Or roll up the
              hammock with foam pad inside?
            • geoflyfisher <geoflyfisher@yahoo.com>
              After my post yesterday... Thanks to all who responded with great ideas, I got an email off list pointing me to the Garlington insulator, a taco shell
              Message 6 of 20 , Feb 6, 2003
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                After my post yesterday... Thanks to all who responded with great
                ideas, I got an email off list pointing me to the Garlington
                insulator, a "taco" shell hanging below the hammock. R. Garlington
                (first name unknown to me) has a site describing the contraption at:

                http://www.mindspring.com/~rgarling/Insulator.htm

                I built one last night, having a bit of silnylon on hand for a
                project I will not do, and hope to test it soon in our cold weather.

                Ed mentioned in his post that insulation is inefficient if a lot of
                sag exists between the hammock and the insulation. Great point, that
                I had forgotten. Since the warmth will be due to my body heating up
                the insulation area, a large space will take more energy to heat than
                a rather small space. (Vpor barrier warming methods are the ultamet
                end of this line of reasoning.) But having a couple inches of dead
                space can take less energy than having many inches of dead space...
                if there is little gradient across that dead space... ie if the space
                is not filled with many little spaces like down.

                The other problem is movement in the space. The more the space moves
                around, the more mixing occurs, and the more heat is lost by the
                enhanced convection.

                The Garlington insulator attempts to minimize this motion and a
                uniformly medium thick layer of dead space by sandwitching plastic
                gargage bags, partly inflated with air between the hammock and a
                silnylon shell.

                Well, its a great theory. And it is going to be cold tonight...
                maybe too cold at 10, but I may get a data point tonight or soon.

                Rick
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