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Bottom Quilt for HH...

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  • Susan Turner <HammockHanger@attbi.com>
    Well I took an old unused worn down sleeping bag and recycled the down for an outside underneath quilt for the Hennessy Hammock. I used sil-nylon for the part
    Message 1 of 20 , Jan 28, 2003
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      Well I took an old unused worn down sleeping bag and recycled the
      down for an outside underneath quilt for the Hennessy Hammock. I used
      sil-nylon for the part that is exposed and a light fleece-like
      material for the layer that will be directly under the hammock. I
      attached it with some small plastic hooks and a little velcro. It
      stuffs up small and seems very light. Haven't weighed it yet. I
      will be trying it out on a President Wknd hike. Hammock Hanger
    • Ed Speer
      Sounds good, Hammock Hanger! How thick is the insulation? I m curious because I m putting together a table of
      Message 2 of 20 , Jan 28, 2003
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        Sounds good, Hammock Hanger!  How thick is the insulation?  I'm curious because I'm putting together a table of recommended insulation thickness vs temperature.  Also anxious to know how down works for this application.
         
        I was working on a new sleeping bag prototype today myself; but this one is not for hammock use.  It incorporate some of the features of my PeaPod, but will be a general-purpose summer bag....Ed
        Well I took an old unused worn down sleeping bag and recycled the
        down for an outside underneath quilt for the Hennessy Hammock. I used
        sil-nylon for the part that is exposed and a light fleece-like
        material for the layer that will be directly under the hammock.  I
        attached it with some small plastic hooks and a little velcro.  It
        stuffs up small and seems very light.  Haven't weighed it yet.  I
        will be trying it out on a President Wknd hike.  Hammock Hanger

      • wsmurdoch@aol.com
        ... Gerry Cunningham in Light Weight Camping Equipment and How to Make It 4th ed. page 117 quotes a table from A.C. Burton, Man in a Cold Environment ,
        Message 3 of 20 , Jan 29, 2003
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          In a message dated 1/29/03 "Ed Speer" <info@...> writes:



             From: "Ed Speer" <info@...>
          Subject: RE: Bottom Quilt for HH...


          Sounds good, Hammock Hanger!  How thick is the insulation?  I'm curious
          because I'm putting together a table of recommended insulation thickness
          vs temperature. 


          Gerry Cunningham in "Light Weight Camping Equipment and How to Make It" 4th ed. page 117 quotes a table from A.C. Burton, "Man in a Cold Environment", Williams & Wilkins Co., 1955. which gives the required thickness from skin to the outer garment layer.

          Temp.  Sleeping  Light Work  Heavy Work 
          40°F    1.5"       0.8"       0.20"
          20°F    2.0"       1.0"       0.27"
            0°F    2.5"       1.3"       0.35"
          -20°F    3.0"       1.6"       0.40"
          -40°F    3.5"       1.9"       0.48"
          -60°F    4.0"       2.1"       0.52"

          I have tried and failed to find the original work.

          Bill Murdoch
        • Ed Speer
          Thanks Bill, that s exactly the kind of table I was thinking about. The numbers are even close to my own observations, which just confirms my suspection that
          Message 4 of 20 , Jan 29, 2003
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            Thanks Bill, that's exactly the kind of table I was thinking about.  The numbers are even close to my own observations, which just confirms my suspection that thickness of insulation is the real key to warmth, not the difference between the various types of insulation.  I'll take everyone's response to my call for their actual personal tests and compile a similar table for hammocks....Ed
            Gerry Cunningham in "Light Weight Camping Equipment and How to Make It" 4th ed. page 117 quotes a table from A.C. Burton, "Man in a Cold Environment", Williams & Wilkins Co., 1955. which gives the required thickness from skin to the outer garment layer.

            Temp.  Sleeping  Light Work  Heavy Work 
            40°F    1.5"       0.8"       0.20"
            20°F    2.0"       1.0"       0.27"
              0°F    2.5"       1.3"       0.35"
            -20°F    3.0"       1.6"       0.40"
            -40°F    3.5"       1.9"       0.48"
            -60°F    4.0"       2.1"       0.52"

            I have tried and failed to find the original work.

            Bill Murdoch


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          • debweisenstein <dweisens@aer.com>
            I don t believe the Cunningham/Burton table. At least it sure wouldn t work for me. Here s a sleeping table put together from my own experience and by
            Message 5 of 20 , Jan 30, 2003
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              I don't believe the Cunningham/Burton table. At least it sure
              wouldn't work for me. Here's a sleeping table put together from my own
              experience and by checking some sleeping bag loft vs temperature
              ratings (but watch out for manufacturer's rating - they can be way
              off). I may sleep colder than alot of people, but I've been winter
              camping in New England for years and know what works for me down to
              -26F. This assumes minimal clothing inside the sleeping bag but use
              in a tent or other environment protected from wind.

              Temp. Sleeping Bag Loft Single Thickness
              40 3-3.5 1.5-1.75
              30 4 inches 2.0
              20 5.5 2.75
              10 6-6.5 3-3.25
              0 7 3.5
              -10 7.5-8 3.75-4
              -20 8-9 4-4.5



              >
              > Gerry Cunningham in "Light Weight Camping Equipment and How to Make
              It" 4th
              > ed. page 117 quotes a table from A.C. Burton, "Man in a Cold
              Environment",
              > Williams & Wilkins Co., 1955. which gives the required thickness
              from skin to
              > the outer garment layer.
              >
              > Temp. Sleeping Light Work Heavy Work
              > 40°F 1.5" 0.8" 0.20"
              > 20°F 2.0" 1.0" 0.27"
              > 0°F 2.5" 1.3" 0.35"
              > -20°F 3.0" 1.6" 0.40"
              > -40°F 3.5" 1.9" 0.48"
              > -60°F 4.0" 2.1" 0.52"
              >
              > I have tried and failed to find the original work.
              >
              > Bill Murdoch
            • Ed Speer
              My feelings too, Debra. I assume the Cunningham/Burton table refered to stay-alive temps, not the toasty warm temps I need for comfortable sleep. Your
              Message 6 of 20 , Jan 30, 2003
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                My feelings too,  Debra.  I assume the Cunningham/Burton table refered to 'stay-alive' temps, not the 'toasty warm' temps I need for comfortable sleep.  Your experience in cold temps confirms this.  Your table is more in line with what I'd recommond to others.  Thanks for compiling it.  I too have culled sleeping bag manufacturer's bag ratings, but also find them too optimistic.  Although I'm still collecting data,  my numbers for recommended hammock bottom insulation are probably going to be very close to yours....Ed
                I don't believe the Cunningham/Burton table.  At least it sure
                wouldn't work for me. Here's a sleeping table put together from my own
                experience and by checking some sleeping bag loft vs temperature
                ratings (but watch out for manufacturer's rating - they can be way
                off).  I may sleep colder than alot of people, but I've been winter
                camping in New  England for years and know what works for me down to
                -26F.  This assumes minimal clothing inside the sleeping bag but use
                in a tent or other environment protected from wind.

                Temp.   Sleeping Bag Loft        Single Thickness
                40         3-3.5                    1.5-1.75
                30         4 inches                   2.0
                20         5.5                       2.75
                10         6-6.5                     3-3.25
                0          7                         3.5
                -10        7.5-8                     3.75-4
                -20        8-9                       4-4.5


                >
                > Gerry Cunningham in "Light Weight Camping Equipment and How to Make
                It" 4th
                > ed. page 117 quotes a table from A.C. Burton, "Man in a Cold
                Environment",
                > Williams & Wilkins Co., 1955. which gives the required thickness
                from skin to
                > the outer garment layer.
                >
                > Temp.  Sleeping  Light Work  Heavy Work 
                >  40°F    1.5"       0.8"       0.20"
                >  20°F    2.0"       1.0"       0.27"
                >   0°F    2.5"       1.3"       0.35"
                > -20°F    3.0"       1.6"       0.40"
                > -40°F    3.5"       1.9"       0.48"
                > -60°F    4.0"       2.1"       0.52"
                >
                > I have tried and failed to find the original work.
                >
                > Bill Murdoch



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              • Matthew Takeda
                Wow! I haven t heard anyone reference Gerry in a long time. I think I got my copy of his book (dunno which edition) around 1971. ... - Matthew Takeda - the
                Message 7 of 20 , Jan 31, 2003
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                  Wow! I haven't heard anyone reference Gerry in a long time. I think I got
                  my copy of his book (dunno which edition) around 1971.

                  Bill Murdoch wrote:
                  >Gerry Cunningham in "Light Weight Camping Equipment and How to Make It" 4th
                  >ed. page 117 ...

                  - Matthew Takeda
                  - the JOAT
                • wsmurdoch@aol.com
                  In a message dated 2/1/03 5:41:31 AM Eastern Standard Time, Matthew Takeda
                  Message 8 of 20 , Feb 2, 2003
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                    In a message dated 2/1/03 5:41:31 AM Eastern Standard Time, Matthew Takeda <takeda@...> writes:



                    Wow! I haven't heard anyone reference Gerry in a long time. I think I got
                    my copy of his book (dunno which edition) around 1971.


                    I got my copy about the same time.  I own two of his down bags and a Fireside tent bought about the same time, all still going strong.

                    Bill Murdoch

                  • Matthew Takeda
                    I have one of his down bags, too. Still going strong. By the way, has anyone seen this?
                    Message 9 of 20 , Feb 3, 2003
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                      I have one of his down bags, too. Still going strong.

                      By the way, has anyone seen this?

                      <http://www.exped.com/exped/web/exped_homepage.nsf/bc533c91605f6841c12566e6006e0c82/abe00eea82521552c1256ae2002374a4!OpenDocument&Highlight=0,down,mattress>

                      <http://www.backcountry-equipment.com/sleeping_pads/exped_downairmattress.html>

                      'Tis not the right shape for an HH, or for my homemade hammock, for that
                      matter, since I lie down diagonally like in an HH. Sounds similar to
                      Stephenson's DAM, and the price is similar, too.

                      I've been experimenting with a quilt between the bottom of my hammock and
                      the "capsule" that goes around it. Something like this, in a parallelogram
                      shape would be nice, especially since it would make a good pad on the
                      ground if I had to use the setup as a bivy if there weren't any trees/rocks
                      to suspend the hammock from. I guess I'm going to have to experiment by
                      making a little baffled quilt with a shell made of coated fabric and with
                      all the seams sealed to see if it'll hold air under pressure from my not
                      inconsiderable body weight overnight.

                      Bill Murdoch wrote:
                      >In a message dated 2/1/03 5:41:31 AM Eastern Standard Time, Matthew Takeda <
                      >takeda@...> writes:
                      >
                      > > Wow! I haven't heard anyone reference Gerry in a long time. I think I got
                      > > my copy of his book (dunno which edition) around 1971.
                      >
                      >I got my copy about the same time. I own two of his down bags and a Fireside
                      >tent bought about the same time, all still going strong.

                      - Matthew Takeda
                      - the JOAT
                    • wsmurdoch@aol.com
                      In a message dated 2/4/03 5:25:34 AM Eastern Standard Time, Matthew Takeda
                      Message 10 of 20 , Feb 4, 2003
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                        In a message dated 2/4/03 5:25:34 AM Eastern Standard Time, Matthew Takeda <takeda@...> writes:


                        I guess I'm going to have to experiment by
                        making a little baffled quilt with a shell made of coated fabric and with
                        all the seams sealed to see if it'll hold air under pressure from my not
                        inconsiderable body weight overnight.


                        Another possibility is in "The Complete Walker", 2nd ed. 

                        "Air Lift of Berkley has recently marketed a new kind of very compact, lightweight air mattress.  Nine strong vinyl tubes -- each inflatable by "a single breath" fit individually into the compartments of a zippered 1.9 oz Rip-stop nylon cover.  This system means you can inflate the outermost tubes hard, and so reduce the danger of rolling off; but to adjust the mattress so your requirements -- and again to deflate it in the morning -- you have 9 separate valve to play with.  (Model 9B: 20 by 42 inches; 1 1/2 pounds; $14.50.  Spare tubes: $1 each.  Model 10-BL: 22 by 72 inches; 2 1/2 pounds; $24.50 {includes patch kit}.  Spare tubes: $2.) Each mattress comes with a sack and spare tube."

                        We (They) have 4" wide flat 4 mil polyethylene tubes at work that come in a several hundred foot roll.  I have thought of slipping a 6 ft piece of polyester batting into a 8 ft piece, rolling the ends up like the peanut butter squeeze tubes, and slipping seven or eight into the compartments between parallel seams through two layers of rip-stop nylon.  That would make a fiber filled air mattress.  My guess is that it would more than 50% self inflate.  If one tube leaked, big deal, I would just swap them around.

                        Bill Murdoch
                      • Ed Speer
                        Thanks for the links to the Expend down-filled air mattress, Matthew. I was not aware of these. Like you said they sound similar to the Warmlight DAM, which
                        Message 11 of 20 , Feb 4, 2003
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                          Thanks for the links to the Expend down-filled air mattress, Matthew.  I was not aware of these.  Like you said they sound similar to the Warmlight DAM, which I have used successfully in my hammock.  Looks like the Expend would work equally as well...Ed
                          By the way, has anyone seen this?

                          <http://www.exped.com/exped/web/exped_homepage.nsf/bc533c91605f6841c12566e6006e0c82/abe00eea82521552c1256ae2002374a4!OpenDocument&Highlight=0,down,mattress>

                          <http://www.backcountry-equipment.com/sleeping_pads/exped_downairmattress.html>


                          - Matthew Takeda
                          - the JOAT
                        • starnescr <starnescr@yahoo.com>
                          Bill Be carefull. You may be building a better mouse trap. If it works out and the cost is reasonable I would like for you to build me one. Or could you
                          Message 12 of 20 , Feb 4, 2003
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                            Bill

                            Be carefull. You may be building a better mouse trap. If it works
                            out and the cost is reasonable I would like for you to build me one.
                            Or could you supply or tell me where to get these tubes and how to
                            seal them off and add a stopper for adding/removing the air.

                            Coy Boy

                            --- In hammockcamping@yahoogroups.com, wsmurdoch@a... wrote:
                            > In a message dated 2/4/03 5:25:34 AM Eastern Standard Time,
                            Matthew Takeda <
                            > takeda@s...> writes:
                            >
                            >
                            > > I guess I'm going to have to experiment by
                            > > making a little baffled quilt with a shell made of coated fabric
                            and with
                            > > all the seams sealed to see if it'll hold air under pressure
                            from my not
                            > > inconsiderable body weight overnight.
                            >
                            > Another possibility is in "The Complete Walker", 2nd ed.
                            >
                            > "Air Lift of Berkley has recently marketed a new kind of very
                            compact,
                            > lightweight air mattress. Nine strong vinyl tubes -- each
                            inflatable by "a
                            > single breath" fit individually into the compartments of a
                            zippered 1.9 oz
                            > Rip-stop nylon cover. This system means you can inflate the
                            outermost tubes
                            > hard, and so reduce the danger of rolling off; but to adjust the
                            mattress so
                            > your requirements -- and again to deflate it in the morning -- you
                            have 9
                            > separate valve to play with. (Model 9B: 20 by 42 inches; 1 1/2
                            pounds;
                            > $14.50. Spare tubes: $1 each. Model 10-BL: 22 by 72 inches; 2
                            1/2 pounds;
                            > $24.50 {includes patch kit}. Spare tubes: $2.) Each mattress
                            comes with a
                            > sack and spare tube."
                            >
                            > We (They) have 4" wide flat 4 mil polyethylene tubes at work that
                            come in a
                            > several hundred foot roll. I have thought of slipping a 6 ft
                            piece of
                            > polyester batting into a 8 ft piece, rolling the ends up like the
                            peanut
                            > butter squeeze tubes, and slipping seven or eight into the
                            compartments
                            > between parallel seams through two layers of rip-stop nylon. That
                            would make
                            > a fiber filled air mattress. My guess is that it would more than
                            50% self
                            > inflate. If one tube leaked, big deal, I would just swap them
                            around.
                            >
                            > Bill Murdoch
                          • geoflyfisher <geoflyfisher@yahoo.com>
                            Since it is cold outside and my HH arrives in the UPS today, I keep thinking of ways to add warmth. Ed s use of leaves between the hammock and the pea pod
                            Message 13 of 20 , Feb 5, 2003
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                              Since it is cold outside and my HH arrives in the UPS today, I keep
                              thinking of ways to add warmth.

                              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.

                              Has anyone already tried these approaches?? It seems they could add
                              considerable warmth for just a tiny bit of weight (1-2 oz of 1.1 oz
                              material) and almost no bulk.

                              Rick aka Flyfisher <><
                            • Ed Speer
                              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
                              Message 14 of 20 , Feb 5, 2003
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                                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 <><


                              • 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 15 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 <><
                                  >
                                  >
                                  >
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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 16 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 17 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 18 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.
                                        >

                                        >
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                                      • 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 19 of 20 , Feb 6, 2003
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                                          Message
                                          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 20 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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