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Re: Hammock Camping Best gear to stay warm?

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  • Reilly
    you may be onto something here. This may, in part, be why Tom Hennessey said the reflector pad should be as close to the body as possible (especially if the
    Message 1 of 18 , Jan 29, 2003
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      you may be onto something here.
      This may, in part, be why Tom Hennessey said the reflector pad should be as close to the body as possible (especially if the person is wearing fleece for the slight insulating layer).
      ----- Original Message -----
      Sent: Wednesday, January 29, 2003 4:14 PM
      Subject: Hammock Camping Best gear to stay warm?

      Everyone--What do you consider your best piece of gear for staying
      warm?  A special foam pad?, your home-made under blanket?, a
      reflector layer?, etc.

      I'd like to do some thinking outside the box here also.  We all use
      sleep pads, under blankets, sleeping bags, etc, including clothes. 
      How important are the clothes we wear inside the hammock?  I've found
      that non-crushable clothing (pile, fleece) is extremely efficient--
      maybe even more thermally efficient vs weight/bulk than sleep pads or
      under blankets.  The more I wear, the warmer I am.  Has anyone else
      noticed this, or maybe tried bundling up in multiple thick layers of
      fleece?  or wool?  I'm wondering if tight-fitting insulation is not
      better than loose-fitting pads/blankets.

      Bear, does your sleep-pad shawl work because it is close to your skin
      and wraps tight around your body, like a shawl?

      Sleeping bag manufactures have slowly learned over many years that
      tight-fitting mummy type bags are warmer than loose-fitting
      rectangular bags, even if constructed with the same materials.  I'm
      wondering if we might get better use of our insulation if it is tight
      against our bodies....Ed



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    • David Chinell
      Oh geez. Yes. I d also like to add that I ve never noticed any particular benefit from reflective stuff. I find no studies to prove or disprove the theory of
      Message 2 of 18 , Jan 29, 2003
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        Oh geez. Yes. I'd also like to add that I've never noticed any particular benefit from reflective stuff. I find no studies to prove or disprove the theory of reflected radiant heat, but many people whose opinions I respect have convinced me that the effect is illusory.
         
        Bear
      • Ed Speer
        I know that my pads are colder if I put them between my PeaPod and the hammock itself rather than inside the hammock where I would be lying directly ontop of
        Message 3 of 18 , Jan 29, 2003
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          I know that my pads are colder if I put them between my PeaPod and the hammock itself rather than inside the hammock where I would be lying directly ontop of them.  If the pads are a few inches below my body, they are not nearly as warm....Ed
           
          you may be onto something here.
          This may, in part, be why Tom Hennessey said the reflector pad should be as close to the body as possible (especially if the person is wearing fleece for the slight insulating layer).
          ----- Original Message -----
          Sent: Wednesday, January 29, 2003 4:14 PM
          Subject: Hammock Camping Best gear to stay warm?

          Everyone--What do you consider your best piece of gear for staying
          warm?  A special foam pad?, your home-made under blanket?, a
          reflector layer?, etc.

          I'd like to do some thinking outside the box here also.  We all use
          sleep pads, under blankets, sleeping bags, etc, including clothes. 
          How important are the clothes we wear inside the hammock?  I've found
          that non-crushable clothing (pile, fleece) is extremely efficient--
          maybe even more thermally efficient vs weight/bulk than sleep pads or
          under blankets.  The more I wear, the warmer I am.  Has anyone else
          noticed this, or maybe tried bundling up in multiple thick layers of
          fleece?  or wool?  I'm wondering if tight-fitting insulation is not
          better than loose-fitting pads/blankets.

          Bear, does your sleep-pad shawl work because it is close to your skin
          and wraps tight around your body, like a shawl?

          Sleeping bag manufactures have slowly learned over many years that
          tight-fitting mummy type bags are warmer than loose-fitting
          rectangular bags, even if constructed with the same materials.  I'm
          wondering if we might get better use of our insulation if it is tight
          against our bodies....Ed



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        • Ed Speer
          Bear, I know you ve said that before. But my experience is quite the opposite. I ve actually switched non-reflective 1/4 foam pads and 5/16 buble-wrap
          Message 4 of 18 , Jan 29, 2003
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            Bear, I know you've said that before. But my experience is quite the opposite. I've actually switched non-reflective 1/4" foam pads and 5/16" buble-wrap Reflectix pads numerous times on cold nights--the Reflectix pads are significantly warmer.  It generally only takes a few seconds to notice the difference.  True, my tests are based only on my subjective observations; but you've read my story in the book about white vs black shirts on warm sunny days...  I actually call the Reflectix pads 'heat pads' because they will sweat you out on warm days....Ed
            Oh geez. Yes. I'd also like to add that I've never noticed any particular benefit from reflective stuff. I find no studies to prove or disprove the theory of reflected radiant heat, but many people whose opinions I respect have convinced me that the effect is illusory.
             
            Bear
          • Chet Clocksin
            Just wanted to throw my two cents worth in. I have to agree with Ed that the reflector definately provides additional warmth. I feel it almost immediately when
            Message 5 of 18 , Jan 29, 2003
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              Just wanted to throw my two cents worth in. I have to agree with Ed that the reflector definately provides additional warmth. I feel it almost immediately when I lay on top of it with fleece clothes. Test it for yourself with a cheap mylar survival blanket. I just did that the other day and couldn't believe how warm I was wrapped up in the thermo-lite blanket. I may try wrapping the blanket all the way around me and my sleeping bag/blanket the next time I seep in the hammock. I just worry about condensation with it on top of me.
              Chet

              Ed Speer wrote:
              Message
               
              Bear, I know you've said that before. But my experience is quite the opposite. I've actually switched non-reflective 1/4" foam pads and 5/16" buble-wrap Reflectix pads numerous times on cold nights--the Reflectix pads are significantly warmer.  It generally only takes a few seconds to notice the difference.  True, my tests are based only on my subjective observations; but you've read my story in the book about white vs black shirts on warm sunny days...  I actually call the Reflectix pads 'heat pads' because they will sweat you out on warm days....Ed
              Oh geez. Yes. I'd also like to add that I've never noticed any particular benefit from reflective stuff. I find no studies to prove or disprove the theory of reflected radiant heat, but many people whose opinions I respect have convinced me that the effect is illusory.
               
              Bear


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            • Ernest Engman
              I ve been playing around with just using a pad system in my hammock for a while. My latest experiment has just been built, now I m hoping to get some more cold
              Message 6 of 18 , Jan 29, 2003
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                I’ve been playing around with just using a pad system in my hammock for a while. My latest experiment has just been built, now I’m hoping to get some more cold weather to play with it. Pictures and the logic behind it are at my site here: http://hikinghq.net/hammock/wing_pad.html

                 

                Basically I took an Army closed cell foam pad and trimmed it to 68” and rounded the corners. His worked down to 26* with a sunscreen. I added an extra layer under it which also adds wings to the sides so when the hammock cocoons me as I sleep, I get the pad benefit to the side as well as my bag. These wings are actually all the way under me, and are tall enough to go under my butt and shoulders where I get cold first, but doesn’t add a pad under my legs where I don’t need it.

                 

                Then to finish it off, I used some scraps of Tyvek to make the sunscreen mate to the Tyvek without adding weight or complicating the design. I used something similar down to 21* with 12* wind-chill.

                 

                Ernest Engman

                AKA SGT Rock

                sgtrock@...

                http://hikinghq.net

                 

                 

                -----Original Message-----
                From: Chet Clocksin [mailto:cclocksin@...]
                Sent: Wednesday, January 29, 2003 7:07 PM
                To: hammockcamping@yahoogroups.com
                Subject: Re: Hammock Camping Best gear to stay warm?

                 

                Just wanted to throw my two cents worth in. I have to agree with Ed that the reflector definately provides additional warmth. I feel it almost immediately when I lay on top of it with fleece clothes. Test it for yourself with a cheap mylar survival blanket. I just did that the other day and couldn't believe how warm I was wrapped up in the thermo-lite blanket. I may try wrapping the blanket all the way around me and my sleeping bag/blanket the next time I seep in the hammock. I just worry about condensation with it on top of me.
                Chet

                Ed Speer wrote:

                 

                Bear, I know you've said that before. But my experience is quite the opposite. I've actually switched non-reflective 1/4" foam pads and 5/16" buble-wrap Reflectix pads numerous times on cold nights--the Reflectix pads are significantly warmer.  It generally only takes a few seconds to notice the difference.  True, my tests are based only on my subjective observations; but you've read my story in the book about white vs black shirts on warm sunny days...  I actually call the Reflectix pads 'heat pads' because they will sweat you out on warm days....Ed

                Oh geez. Yes. I'd also like to add that I've never noticed any particular benefit from reflective stuff. I find no studies to prove or disprove the theory of reflected radiant heat, but many people whose opinions I respect have convinced me that the effect is illusory.

                 

                Bear



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              • Ed Speer
                Great job on the frankenpad Ernest; the wings and reflector surface look good. What is the thickness of the Army foam pad you used? 1/2 ? Of course, in
                Message 7 of 18 , Jan 29, 2003
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                  Message
                   
                   
                   

                  Great job on the frankenpad Ernest; the wings and reflector surface look good.  What is the thickness of the Army foam pad you used? 1/2"?  Of course, in places this thickness would be doubled.  Now I see how you got down to 21*.....Ed

                  I’ve been playing around with just using a pad system in my hammock for a while. My latest experiment has just been built, now I’m hoping to get some more cold weather to play with it. Pictures and the logic behind it are at my site here: http://hikinghq.net/hammock/wing_pad.html

                   

                  Basically I took an Army closed cell foam pad and trimmed it to 68” and rounded the corners. His worked down to 26* with a sunscreen. I added an extra layer under it which also adds wings to the sides so when the hammock cocoons me as I sleep, I get the pad benefit to the side as well as my bag. These wings are actually all the way under me, and are tall enough to go under my butt and shoulders where I get cold first, but doesn’t add a pad under my legs where I don’t need it.

                   

                  Then to finish it off, I used some scraps of Tyvek to make the sunscreen mate to the Tyvek without adding weight or complicating the design. I used something similar down to 21* with 12* wind-chill.

                   

                  Ernest Engman

                  AKA SGT Rock

                  sgtrock@...

                  http://hikinghq.net

                   

                   

                  -----Original Message-----
                  From: Chet Clocksin [mailto:cclocksin@...]
                  Sent: Wednesday, January 29, 2003 7:07 PM
                  To: hammockcamping@yahoogroups.com
                  Subject: Re: Hammock Camping Best gear to stay warm?

                   

                  Just wanted to throw my two cents worth in. I have to agree with Ed that the reflector definately provides additional warmth. I feel it almost immediately when I lay on top of it with fleece clothes. Test it for yourself with a cheap mylar survival blanket. I just did that the other day and couldn't believe how warm I was wrapped up in the thermo-lite blanket. I may try wrapping the blanket all the way around me and my sleeping bag/blanket the next time I seep in the hammock. I just worry about condensation with it on top of me.
                  Chet

                  Ed Speer wrote:

                   

                  Bear, I know you've said that before. But my experience is quite the opposite. I've actually switched non-reflective 1/4" foam pads and 5/16" buble-wrap Reflectix pads numerous times on cold nights--the Reflectix pads are significantly warmer.  It generally only takes a few seconds to notice the difference.  True, my tests are based only on my subjective observations; but you've read my story in the book about white vs black shirts on warm sunny days...  I actually call the Reflectix pads 'heat pads' because they will sweat you out on warm days....Ed

                  Oh geez. Yes. I'd also like to add that I've never noticed any particular benefit from reflective stuff. I find no studies to prove or disprove the theory of reflected radiant heat, but many people whose opinions I respect have convinced me that the effect is illusory.

                   

                  Bear



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                • David Chinell
                  MessageEd: I m perfectly happy to defer to your experience. I ve only experimented with space blankets in various configurations and positions, never with
                  Message 8 of 18 , Jan 30, 2003
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                    Ed: I'm perfectly happy to defer to your experience. I've only experimented with space blankets in various configurations and positions, never with reflectix. I'll keep an open mind, and maybe experiment with some if it jumps out at me in Home Depot. (I'm still waiting for some aluminum flashing to fall into my cart so I can make a windscreen for my stove. No luck so far.) -- Bear
                     
                    -----Original Message-----
                    From: Ed Speer [mailto:info@...]
                    Sent: Wednesday, January 29, 2003 07:52 PM
                    To: hammockcamping@yahoogroups.com
                    Subject: RE: Hammock Camping Best gear to stay warm?

                     
                    Bear, I know you've said that before. But my experience is quite the opposite. I've actually switched non-reflective 1/4" foam pads and 5/16" buble-wrap Reflectix pads numerous times on cold nights--the Reflectix pads are significantly warmer.  It generally only takes a few seconds to notice the difference.  True, my tests are based only on my subjective observations; but you've read my story in the book about white vs black shirts on warm sunny days...  I actually call the Reflectix pads 'heat pads' because they will sweat you out on warm days....Ed
                    Oh geez. Yes. I'd also like to add that I've never noticed any particular benefit from reflective stuff. I find no studies to prove or disprove the theory of reflected radiant heat, but many people whose opinions I respect have convinced me that the effect is illusory.
                     
                    Bear

                  • David Chinell
                    MessageSarge: Thanks for the R&D work. I m dreaming along the same lines. That s what the evazote shawl is about -- extra width between the hips and
                    Message 9 of 18 , Jan 30, 2003
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                      Sarge: Thanks for the R&D work. I'm dreaming along the same lines. That's what the evazote "shawl" is about -- extra width between the hips and shoulders.
                       
                      But I need to make a cloth casing to hold the wings so they're detachable, rather than permanent, so I can roll it all up in a single, 24-inch wide roll. How do you pack the Frankenpad?
                       
                      And if, as you say, "heat reflectors are snake oil" why do you use a windshield reflector? Why not just another pad?
                       
                      Bear
                       
                    • Ernest Engman
                      The pad I use serves a couple of purposes. 1. Wind/air barrier. It is made of aluminum coated close cell foam pad. I can use it alone in cool but not cold
                      Message 10 of 18 , Feb 2, 2003
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                        Message

                        The pad I use serves a couple of purposes.

                         

                        1. Wind/air barrier. It is made of aluminum coated close cell foam pad. I can use it alone in cool but not cold temps by turning it shiny side down and preventing air circulation.
                        2. Since it is also foam, it adds a light and small layer of insulation.
                        3. It serves as a ground pad under the hammock when I lay it on the ground to stay warm. It is wide and long enough for that. Often when having to do this, the ground isn’t dry and no sense getting the fabric wet.
                        4. Closed cell foam pads work better against a non-breathable barrier than against a breathable material like than hammock. See this excellent post by youngblood: http://hikinghq.net/forum/showthread.php?s=10900e520cfd29662ed8485b43febff2&threadid=359

                         

                        I say heat reflectors are snake oil, because the science that says they are a radiant heat reflector for someone sleeping in a hammock is highly flawed.

                         

                        Ernest Engman

                        AKA SGT Rock

                        sgtrock@...

                        http://hikinghq.net

                         

                         

                        -----Original Message-----
                        From: David Chinell [mailto:dchinell@...]
                        Sent: Thursday, January 30, 2003 9:25 AM
                        To: hammockcamping@yahoogroups.com
                        Subject: RE: Hammock Camping Franken pad and bride of Frankenpad

                         

                        Sarge: Thanks for the R&D work. I'm dreaming along the same lines. That's what the evazote "shawl" is about -- extra width between the hips and shoulders.

                         

                        But I need to make a cloth casing to hold the wings so they're detachable, rather than permanent, so I can roll it all up in a single, 24-inch wide roll. How do you pack the Frankenpad?

                         

                        And if, as you say, "heat reflectors are snake oil" why do you use a windshield reflector? Why not just another pad?

                         

                        Bear

                         


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                      • starnescr <starnescr@yahoo.com>
                        If a reflectic pad is snake oil then why are emergency blankets made of reflective material. Of course you wrap a space blanket around you and are not laying
                        Message 11 of 18 , Feb 2, 2003
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                          If a reflectic pad is snake oil then why are "emergency blankets
                          made of reflective material. Of course you wrap a space blanket
                          around you and are not laying on it only. Would a reflective pad be
                          more effective (no mater how unpracticle) if it went all the way
                          around you. I think the reflective pad is somewhat usefull if you
                          are not laying directly on it. From what Tom Hennessy and others
                          have said there needs to be a little space between the heat source
                          and the reflective surface. Hence my fleece covered reflectic pad.
                          A 1/2 inch closed cell foam pad the same size as mine would be
                          heavier but I'm not sure how much. I'm not saying a reflective pad
                          is the answer either. I just believe given the same R value a
                          reflective pad would be slightly warmer.

                          Coy Boy

                          --- In hammockcamping@yahoogroups.com, "Ernest Engman"
                          <ebengman@h...> wrote:
                          > The pad I use serves a couple of purposes.
                          >
                          > 1. Wind/air barrier. It is made of aluminum coated close cell
                          foam
                          > pad. I can use it alone in cool but not cold temps by turning it
                          shiny
                          > side down and preventing air circulation.
                          > 2. Since it is also foam, it adds a light and small layer of
                          > insulation.
                          > 3. It serves as a ground pad under the hammock when I lay it on
                          the
                          > ground to stay warm. It is wide and long enough for that. Often
                          when
                          > having to do this, the ground isn't dry and no sense getting the
                          fabric
                          > wet.
                          > 4. Closed cell foam pads work better against a non-breathable
                          > barrier than against a breathable material like than hammock. See
                          this
                          > excellent post by youngblood:
                          > http://hikinghq.net/forum/showthread.php?
                          s=10900e520cfd29662ed8485b43feb
                          > ff2
                          > <http://hikinghq.net/forum/showthread.php?
                          s=10900e520cfd29662ed8485b43fe
                          > bff2&threadid=359> &threadid=359
                          >
                          > I say heat reflectors are snake oil, because the science that says
                          they
                          > are a radiant heat reflector for someone sleeping in a hammock is
                          highly
                          > flawed.
                          >
                          > Ernest Engman
                          > AKA SGT Rock
                          > sgtrock@h...
                          > <http://hikinghq.net/> http://hikinghq.net
                          >
                          >
                          > -----Original Message-----
                          > From: David Chinell [mailto:dchinell@m...]
                          > Sent: Thursday, January 30, 2003 9:25 AM
                          > To: hammockcamping@yahoogroups.com
                          > Subject: RE: Hammock Camping Franken pad and bride of Frankenpad
                          >
                          > Sarge: Thanks for the R&D work. I'm dreaming along the same lines.
                          > That's what the evazote "shawl" is about -- extra width between
                          the hips
                          > and shoulders.
                          >
                          > But I need to make a cloth casing to hold the wings so they're
                          > detachable, rather than permanent, so I can roll it all up in a
                          single,
                          > 24-inch wide roll. How do you pack the Frankenpad?
                          >
                          > And if, as you say, "heat reflectors are snake oil" why do you use
                          a
                          > windshield reflector? Why not just another pad?
                          >
                          > Bear
                          >
                          >
                          > To unsubscribe from this group, send an email to:
                          > hammockcamping-unsubscribe@yahoogroups.com
                          >
                          >
                          >
                          > Your use of Yahoo! Groups is subject to the Yahoo!
                          > <http://docs.yahoo.com/info/terms/> Terms of Service.
                        • Ernest Engman
                          If reflective pads are so good, then why not a sleeping bag that is made from them? They aren t. Can a space blanket really work? Somewhat, but I ve never bet
                          Message 12 of 18 , Feb 2, 2003
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                            If reflective pads are so good, then why not a sleeping bag that is made
                            from them? They aren't. Can a space blanket really work? Somewhat, but
                            I've never bet my life on one and will never do so because the theory
                            that tells you they will is very flawed. But people buy them, so people
                            will sell them.

                            My position that radiant heat reflectors are snake oil has grown over
                            time, and after a couple of debates with some people smarter than I, I'm
                            sure of it.

                            The science is this, and don't take it is as just me, this is from an
                            aerospace engineer working for NASA and another engineer that have both
                            convinced me of this:

                            Heat isn't as simple as saying 25% of your body heat is lost thru
                            radiant heat loss. It is much more complicated than that. On a night
                            with high humidity but low temperature, you will be a lot colder than on
                            a night with the same temp with lower humidity. Why? Because the
                            moisture in the air is conductive, same principle as sleeping in a wet
                            bag in a way, but you are loosing more of a percent of heat this way and
                            less thru radiant heat. Same thing in high winds. How can higher winds
                            make that big a difference if more is lost thru radiant heat loss? It
                            couldn't but the real problem is demonstrated by this is convective heat
                            loss. I hope this isn't too much of a tangent for the discussion, but it
                            just shows how one factor can change the percentages.

                            Radiant heat reflectors (actually insulators) were made to work in
                            space. In space there isn't any air flow at all to worry about, so
                            absolutely no convective heat loss to worry about. In space they not
                            only have to protect the person from heat loss, but excessive heat gain
                            from solar radiant heat. Ever hear that in space one side will freeze
                            while the side facing the sun would burn up?

                            So what is heat? Heat is energy, cold isn't the opposite, it is the
                            absence of heat. Heat energy, by its nature, will try to equalize the
                            energy from places of higher energy to places of lower energy. If your
                            body is the point of higher energy (which it normally is at night) then
                            your heat energy will attempt to displace outward.

                            There are about 4 means of heat loss that you must worry about.

                            1. Evaporation. When you sweat or breathe, the water loss from your body
                            carries heat energy with it. To prevent this you can wrap yourself in a
                            vapor barrier. But to make this work, you will most likely want to be
                            totally undressed or you will end up in soggy clothing which is also
                            bad. Ed talks about always allowing your breath a way to get out - very
                            important!

                            2. Radiant heat loss (the main topic) which is heat transfer based on
                            how IR opaque or transparent barriers between you and the object are. If
                            you were to stand naked in a freezer, you would loose a great deal of
                            body heat thru radiant heat loss. Wrap yourself in a space blanket, and
                            you would reflect about 50% of your heat loss back at yourself because
                            the air will still carry away some through convection. But to reduce
                            this loss, you can wear clothing. Since the clothing is essentially IR
                            opaque, you can reduce this loss of you radiant heat energy down to
                            about 5% of your original loss. So if you have a given (which I disagree
                            with) of 25% heat loss thru radiant heat, and reduce that to 5% of the
                            original loss by wearing clothing, then you are down to less than 2% of
                            your total body heat loss. Now use a radiant heat reflector to capture
                            50% of that, and it is returning less than 1% of your total body heat
                            lost. This 95% (give or take) heat loss prevention occurs for every
                            layer of IR opaque material between you, and the colder objects around
                            you. So if you wear clothing, then a sleeping bag (inside layer) then
                            you already have reduced your IR heat loss to less than 1%.

                            For a radiant heat reflector to work (in the atmosphere) you would need
                            to be inside it without clothing and not touch it (which is where I'm
                            going next) for it to be of any help. Interestingly Stephensons
                            Warmlight sleeping bags understands this and explains it quite well for
                            someone looking at their bags.

                            To prove this, feel free to make a shower curtain of mylar then turn
                            your heat off. Stand inside the shower with the curtain nude and see if
                            it (the curtain) gets warm. It won't. You are not a big enough an
                            emitter of IR to make it work. The sun is a huge IR heat emitter and
                            does this quite well, unfortunately our bodies don't come with a huge
                            supply of self heating hydrogen.

                            3. Convective heat loss. When air passes around your body, it carries
                            away heat; this is the biggest problem keeping warm in an atmosphere.
                            The trick is to stop air from passing around you and create pockets of
                            still air that can be warmed and kept into place. Sleeping bags and pads
                            are designed to do this. Again, if radiant heat reflectors were truly
                            beneficial, then that is how we should have been staying warm for the
                            last 50 years in the hiking world, but so far we all still use sleeping
                            bags and pads. Ed has done a great job of figuring out how to make this
                            happen with a pea pod. And to make it even better would be to surround
                            the pod with a waterproof material that totally stopped any air from
                            getting out and totally stopped any moisture from getting out. Foil wrap
                            does a great job of this, by the way - that is what a space blanket is
                            made from. But it also has a drawback that it traps moisture that
                            destroys loft in a down bag. The best solution would be some material
                            that could surround your pea pot and prevent air flow in, strip heat on
                            the way out for moisture, and wouldn't suffocate you.

                            4. Conductive heat loss. This is a problem because some people try
                            laying directly on the reflective surfaces which are also excellent
                            conductors. Some spots under these conductors are warm because they
                            prevent evaporation or convection, but they also conduct heat away. This
                            is also how the moisture carries away your body heat.

                            So to conclude this lengthy post and spark the debate I don't mean to.
                            Radiant heat reflectors are not that inside the atmosphere, they are
                            serving as barriers to convective heat and if used right, evaporative
                            heat. I've never said that people using a system that involves a "Heat
                            Rflector" aren't staying warm (heck I have one) I'm just saying they
                            should get smart about why they work and figure the best applications
                            for these materials. Aluminized plastic (mylar) is very good at blocking
                            moisture, and it is what all really long shelf life packet foods are now
                            packed in.

                            Ernest Engman
                            AKA SGT Rock
                            sgtrock@...
                            http://hikinghq.net



                            -----Original Message-----
                            From: starnescr <starnescr@...> [mailto:starnescr@...]
                            Sent: Sunday, February 02, 2003 1:37 PM
                            To: hammockcamping@yahoogroups.com
                            Subject: Re: Hammock Camping Franken pad and bride of Frankenpad

                            If a reflectic pad is snake oil then why are "emergency blankets
                            made of reflective material. Of course you wrap a space blanket
                            around you and are not laying on it only. Would a reflective pad be
                            more effective (no mater how unpracticle) if it went all the way
                            around you. I think the reflective pad is somewhat usefull if you
                            are not laying directly on it. From what Tom Hennessy and others
                            have said there needs to be a little space between the heat source
                            and the reflective surface. Hence my fleece covered reflectic pad.
                            A 1/2 inch closed cell foam pad the same size as mine would be
                            heavier but I'm not sure how much. I'm not saying a reflective pad
                            is the answer either. I just believe given the same R value a
                            reflective pad would be slightly warmer.

                            Coy Boy

                            --- In hammockcamping@yahoogroups.com, "Ernest Engman"
                            <ebengman@h...> wrote:
                            > The pad I use serves a couple of purposes.
                            >
                            > 1. Wind/air barrier. It is made of aluminum coated close cell
                            foam
                            > pad. I can use it alone in cool but not cold temps by turning it
                            shiny
                            > side down and preventing air circulation.
                            > 2. Since it is also foam, it adds a light and small layer of
                            > insulation.
                            > 3. It serves as a ground pad under the hammock when I lay it on
                            the
                            > ground to stay warm. It is wide and long enough for that. Often
                            when
                            > having to do this, the ground isn't dry and no sense getting the
                            fabric
                            > wet.
                            > 4. Closed cell foam pads work better against a non-breathable
                            > barrier than against a breathable material like than hammock. See
                            this
                            > excellent post by youngblood:
                            > http://hikinghq.net/forum/showthread.php?
                            s=10900e520cfd29662ed8485b43feb
                            > ff2
                            > <http://hikinghq.net/forum/showthread.php?
                            s=10900e520cfd29662ed8485b43fe
                            > bff2&threadid=359> &threadid=359
                            >
                            > I say heat reflectors are snake oil, because the science that says
                            they
                            > are a radiant heat reflector for someone sleeping in a hammock is
                            highly
                            > flawed.
                            >
                            > Ernest Engman
                            > AKA SGT Rock
                            > sgtrock@h...
                            > <http://hikinghq.net/> http://hikinghq.net
                            >
                            >
                            > -----Original Message-----
                            > From: David Chinell [mailto:dchinell@m...]
                            > Sent: Thursday, January 30, 2003 9:25 AM
                            > To: hammockcamping@yahoogroups.com
                            > Subject: RE: Hammock Camping Franken pad and bride of Frankenpad
                            >
                            > Sarge: Thanks for the R&D work. I'm dreaming along the same lines.
                            > That's what the evazote "shawl" is about -- extra width between
                            the hips
                            > and shoulders.
                            >
                            > But I need to make a cloth casing to hold the wings so they're
                            > detachable, rather than permanent, so I can roll it all up in a
                            single,
                            > 24-inch wide roll. How do you pack the Frankenpad?
                            >
                            > And if, as you say, "heat reflectors are snake oil" why do you use
                            a
                            > windshield reflector? Why not just another pad?
                            >
                            > Bear
                            >
                            >
                            > To unsubscribe from this group, send an email to:
                            > hammockcamping-unsubscribe@yahoogroups.com
                            >
                            >
                            >
                            > Your use of Yahoo! Groups is subject to the Yahoo!
                            > <http://docs.yahoo.com/info/terms/> Terms of Service.


                            To unsubscribe from this group, send an email to:
                            hammockcamping-unsubscribe@yahoogroups.com



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                          • starnescr <starnescr@yahoo.com>
                            That s why I said slightly warmer. I would be interested if anyone has tested how warm a space blanket is compared to say a waterproof silnylon space
                            Message 13 of 18 , Feb 2, 2003
                            • 0 Attachment
                              That's why I said slightly warmer. I would be interested if anyone
                              has tested how warm a space blanket is compared to say a waterproof
                              silnylon "space" blanket.

                              I'll have to admit I'm not as smart as NASA engeniers except for
                              maybe Gordo.

                              Coy Boy

                              --- In hammockcamping@yahoogroups.com, "Ernest Engman"
                              <ebengman@h...> wrote:
                              > If reflective pads are so good, then why not a sleeping bag that
                              is made
                              > from them? They aren't. Can a space blanket really work? Somewhat,
                              but
                              > I've never bet my life on one and will never do so because the
                              theory
                              > that tells you they will is very flawed. But people buy them, so
                              people
                              > will sell them.
                              >
                              > My position that radiant heat reflectors are snake oil has grown
                              over
                              > time, and after a couple of debates with some people smarter than
                              I, I'm
                              > sure of it.
                              >
                              > The science is this, and don't take it is as just me, this is from
                              an
                              > aerospace engineer working for NASA and another engineer that have
                              both
                              > convinced me of this:
                              >
                              > Heat isn't as simple as saying 25% of your body heat is lost thru
                              > radiant heat loss. It is much more complicated than that. On a
                              night
                              > with high humidity but low temperature, you will be a lot colder
                              than on
                              > a night with the same temp with lower humidity. Why? Because the
                              > moisture in the air is conductive, same principle as sleeping in a
                              wet
                              > bag in a way, but you are loosing more of a percent of heat this
                              way and
                              > less thru radiant heat. Same thing in high winds. How can higher
                              winds
                              > make that big a difference if more is lost thru radiant heat loss?
                              It
                              > couldn't but the real problem is demonstrated by this is
                              convective heat
                              > loss. I hope this isn't too much of a tangent for the discussion,
                              but it
                              > just shows how one factor can change the percentages.
                              >
                              > Radiant heat reflectors (actually insulators) were made to work in
                              > space. In space there isn't any air flow at all to worry about, so
                              > absolutely no convective heat loss to worry about. In space they
                              not
                              > only have to protect the person from heat loss, but excessive heat
                              gain
                              > from solar radiant heat. Ever hear that in space one side will
                              freeze
                              > while the side facing the sun would burn up?
                              >
                              > So what is heat? Heat is energy, cold isn't the opposite, it is the
                              > absence of heat. Heat energy, by its nature, will try to equalize
                              the
                              > energy from places of higher energy to places of lower energy. If
                              your
                              > body is the point of higher energy (which it normally is at night)
                              then
                              > your heat energy will attempt to displace outward.
                              >
                              > There are about 4 means of heat loss that you must worry about.
                              >
                              > 1. Evaporation. When you sweat or breathe, the water loss from
                              your body
                              > carries heat energy with it. To prevent this you can wrap yourself
                              in a
                              > vapor barrier. But to make this work, you will most likely want to
                              be
                              > totally undressed or you will end up in soggy clothing which is
                              also
                              > bad. Ed talks about always allowing your breath a way to get out -
                              very
                              > important!
                              >
                              > 2. Radiant heat loss (the main topic) which is heat transfer based
                              on
                              > how IR opaque or transparent barriers between you and the object
                              are. If
                              > you were to stand naked in a freezer, you would loose a great deal
                              of
                              > body heat thru radiant heat loss. Wrap yourself in a space
                              blanket, and
                              > you would reflect about 50% of your heat loss back at yourself
                              because
                              > the air will still carry away some through convection. But to
                              reduce
                              > this loss, you can wear clothing. Since the clothing is
                              essentially IR
                              > opaque, you can reduce this loss of you radiant heat energy down to
                              > about 5% of your original loss. So if you have a given (which I
                              disagree
                              > with) of 25% heat loss thru radiant heat, and reduce that to 5% of
                              the
                              > original loss by wearing clothing, then you are down to less than
                              2% of
                              > your total body heat loss. Now use a radiant heat reflector to
                              capture
                              > 50% of that, and it is returning less than 1% of your total body
                              heat
                              > lost. This 95% (give or take) heat loss prevention occurs for every
                              > layer of IR opaque material between you, and the colder objects
                              around
                              > you. So if you wear clothing, then a sleeping bag (inside layer)
                              then
                              > you already have reduced your IR heat loss to less than 1%.
                              >
                              > For a radiant heat reflector to work (in the atmosphere) you would
                              need
                              > to be inside it without clothing and not touch it (which is where
                              I'm
                              > going next) for it to be of any help. Interestingly Stephensons
                              > Warmlight sleeping bags understands this and explains it quite
                              well for
                              > someone looking at their bags.
                              >
                              > To prove this, feel free to make a shower curtain of mylar then
                              turn
                              > your heat off. Stand inside the shower with the curtain nude and
                              see if
                              > it (the curtain) gets warm. It won't. You are not a big enough an
                              > emitter of IR to make it work. The sun is a huge IR heat emitter
                              and
                              > does this quite well, unfortunately our bodies don't come with a
                              huge
                              > supply of self heating hydrogen.
                              >
                              > 3. Convective heat loss. When air passes around your body, it
                              carries
                              > away heat; this is the biggest problem keeping warm in an
                              atmosphere.
                              > The trick is to stop air from passing around you and create
                              pockets of
                              > still air that can be warmed and kept into place. Sleeping bags
                              and pads
                              > are designed to do this. Again, if radiant heat reflectors were
                              truly
                              > beneficial, then that is how we should have been staying warm for
                              the
                              > last 50 years in the hiking world, but so far we all still use
                              sleeping
                              > bags and pads. Ed has done a great job of figuring out how to make
                              this
                              > happen with a pea pod. And to make it even better would be to
                              surround
                              > the pod with a waterproof material that totally stopped any air
                              from
                              > getting out and totally stopped any moisture from getting out.
                              Foil wrap
                              > does a great job of this, by the way - that is what a space
                              blanket is
                              > made from. But it also has a drawback that it traps moisture that
                              > destroys loft in a down bag. The best solution would be some
                              material
                              > that could surround your pea pot and prevent air flow in, strip
                              heat on
                              > the way out for moisture, and wouldn't suffocate you.
                              >
                              > 4. Conductive heat loss. This is a problem because some people try
                              > laying directly on the reflective surfaces which are also excellent
                              > conductors. Some spots under these conductors are warm because they
                              > prevent evaporation or convection, but they also conduct heat
                              away. This
                              > is also how the moisture carries away your body heat.
                              >
                              > So to conclude this lengthy post and spark the debate I don't mean
                              to.
                              > Radiant heat reflectors are not that inside the atmosphere, they
                              are
                              > serving as barriers to convective heat and if used right,
                              evaporative
                              > heat. I've never said that people using a system that involves
                              a "Heat
                              > Rflector" aren't staying warm (heck I have one) I'm just saying
                              they
                              > should get smart about why they work and figure the best
                              applications
                              > for these materials. Aluminized plastic (mylar) is very good at
                              blocking
                              > moisture, and it is what all really long shelf life packet foods
                              are now
                              > packed in.
                              >
                              > Ernest Engman
                              > AKA SGT Rock
                              > sgtrock@h...
                              > http://hikinghq.net
                              >
                              >
                              >
                              > -----Original Message-----
                              > From: starnescr <starnescr@y...> [mailto:starnescr@y...]
                              > Sent: Sunday, February 02, 2003 1:37 PM
                              > To: hammockcamping@yahoogroups.com
                              > Subject: Re: Hammock Camping Franken pad and bride of Frankenpad
                              >
                              > If a reflectic pad is snake oil then why are "emergency blankets
                              > made of reflective material. Of course you wrap a space blanket
                              > around you and are not laying on it only. Would a reflective pad
                              be
                              > more effective (no mater how unpracticle) if it went all the way
                              > around you. I think the reflective pad is somewhat usefull if you
                              > are not laying directly on it. From what Tom Hennessy and others
                              > have said there needs to be a little space between the heat source
                              > and the reflective surface. Hence my fleece covered reflectic
                              pad.
                              > A 1/2 inch closed cell foam pad the same size as mine would be
                              > heavier but I'm not sure how much. I'm not saying a reflective
                              pad
                              > is the answer either. I just believe given the same R value a
                              > reflective pad would be slightly warmer.
                              >
                              > Coy Boy
                              >
                              > --- In hammockcamping@yahoogroups.com, "Ernest Engman"
                              > <ebengman@h...> wrote:
                              > > The pad I use serves a couple of purposes.
                              > >
                              > > 1. Wind/air barrier. It is made of aluminum coated close cell
                              > foam
                              > > pad. I can use it alone in cool but not cold temps by turning it
                              > shiny
                              > > side down and preventing air circulation.
                              > > 2. Since it is also foam, it adds a light and small layer of
                              > > insulation.
                              > > 3. It serves as a ground pad under the hammock when I lay it on
                              > the
                              > > ground to stay warm. It is wide and long enough for that. Often
                              > when
                              > > having to do this, the ground isn't dry and no sense getting the
                              > fabric
                              > > wet.
                              > > 4. Closed cell foam pads work better against a non-breathable
                              > > barrier than against a breathable material like than hammock.
                              See
                              > this
                              > > excellent post by youngblood:
                              > > http://hikinghq.net/forum/showthread.php?
                              > s=10900e520cfd29662ed8485b43feb
                              > > ff2
                              > > <http://hikinghq.net/forum/showthread.php?
                              > s=10900e520cfd29662ed8485b43fe
                              > > bff2&threadid=359> &threadid=359
                              > >
                              > > I say heat reflectors are snake oil, because the science that
                              says
                              > they
                              > > are a radiant heat reflector for someone sleeping in a hammock
                              is
                              > highly
                              > > flawed.
                              > >
                              > > Ernest Engman
                              > > AKA SGT Rock
                              > > sgtrock@h...
                              > > <http://hikinghq.net/> http://hikinghq.net
                              > >
                              > >
                              > > -----Original Message-----
                              > > From: David Chinell [mailto:dchinell@m...]
                              > > Sent: Thursday, January 30, 2003 9:25 AM
                              > > To: hammockcamping@yahoogroups.com
                              > > Subject: RE: Hammock Camping Franken pad and bride of Frankenpad
                              > >
                              > > Sarge: Thanks for the R&D work. I'm dreaming along the same
                              lines.
                              > > That's what the evazote "shawl" is about -- extra width between
                              > the hips
                              > > and shoulders.
                              > >
                              > > But I need to make a cloth casing to hold the wings so they're
                              > > detachable, rather than permanent, so I can roll it all up in a
                              > single,
                              > > 24-inch wide roll. How do you pack the Frankenpad?
                              > >
                              > > And if, as you say, "heat reflectors are snake oil" why do you
                              use
                              > a
                              > > windshield reflector? Why not just another pad?
                              > >
                              > > Bear
                              > >
                              > >
                              > > To unsubscribe from this group, send an email to:
                              > > hammockcamping-unsubscribe@yahoogroups.com
                              > >
                              > >
                              > >
                              > > Your use of Yahoo! Groups is subject to the Yahoo!
                              > > <http://docs.yahoo.com/info/terms/> Terms of Service.
                              >
                              >
                              > To unsubscribe from this group, send an email to:
                              > hammockcamping-unsubscribe@yahoogroups.com
                              >
                              >
                              >
                              > Your use of Yahoo! Groups is subject to
                              > http://docs.yahoo.com/info/terms/
                            • Ed Speer
                              Good discussion on heat loss Ernest. I think we all agree that the major body heat loss is from conduction, convection, evaporation & respiration. So unless
                              Message 14 of 18 , Feb 2, 2003
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                                Message
                                Good discussion on heat loss Ernest.  I think we all agree that the major body heat loss is from conduction, convection, evaporation & respiration.  So unless one has conquered these, it's pretty pointless to worry about radiant heat loss.  I gather you feel that the warming benefit from reflective fabrics is due to their vapor-barrier properties, not their radiant properties; or at least the radiant advantages are overshadowed by the vapor-barrier advantages.  A good point indeed.  Maybe we like using the Aluminum-coated Mylar emergency blankets because they are so light weight--even lighter than plastic sheeting.  However, I often use my plastic sheet ground cloth as a vapor barrier on the bottom outside of my hammock--does it work as well as the emergency blanket?  Of course, I don't know--they both work well enough to keep using them!
                                 
                                I'd be interested in seeing dependable numbers on actual body heat loss by the various processes.   I have found the following, but its' incomplete for our purposes:
                                 
                                "The human body at rest losses 76% of it's heat due to conduction, convection and radiation; the remaining 24% is lost through evaporation, insensible perspiration and respiration".
                                 
                                It would perhaps be useful if we knew exactly how much each process contributes.  Then again, nature is never a constant--like you said, things like wind and humidity greatly change the rules.  So maybe exact numbers are impossible to determine.
                                 
                                Thanks for your reasoned discussion...Ed
                                 

                                 
                              • Ernest Engman
                                Thanks Ed. I think the two strongest sections of your book are the part on cold weather and building a hammock IMHO. And again, I hope everyone doesn t think
                                Message 15 of 18 , Feb 2, 2003
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                                  Message

                                  Thanks Ed. I think the two strongest sections of your book are the part on cold weather and building a hammock IMHO.

                                   

                                  And again, I hope everyone doesn’t think I’m putting them down for using a heat reflector or thinking the reason that they are staying warm is radiant heat reflection. I’m just certain now more than ever that there isn’t the science to support that. BUT, people using them are staying warm. If that is true, then how? If we can figure that out, then maybe more efficient systems can be found to make it work.

                                   

                                  Ernest Engman

                                  AKA SGT Rock

                                  sgtrock@...

                                  http://hikinghq.net

                                   

                                   

                                  -----Original Message-----
                                  From: Ed Speer [mailto:info@...]
                                  Sent:
                                  Sunday, February 02, 2003 6:31 PM
                                  To: hammockcamping@yahoogroups.com
                                  Subject: Hammock Camping RE: Radiant Heat Reflectors

                                   

                                  Good discussion on heat loss Ernest.  I think we all agree that the major body heat loss is from conduction, convection, evaporation & respiration.  So unless one has conquered these, it's pretty pointless to worry about radiant heat loss.  I gather you feel that the warming benefit from reflective fabrics is due to their vapor-barrier properties, not their radiant properties; or at least the radiant advantages are overshadowed by the vapor-barrier advantages.  A good point indeed.  Maybe we like using the Aluminum-coated Mylar emergency blankets because they are so light weight--even lighter than plastic sheeting.  However, I often use my plastic sheet ground cloth as a vapor barrier on the bottom outside of my hammock--does it work as well as the emergency blanket?  Of course, I don't know--they both work well enough to keep using them!

                                   

                                  I'd be interested in seeing dependable numbers on actual body heat loss by the various processes.   I have found the following, but its' incomplete for our purposes:

                                   

                                  "The human body at rest losses 76% of it's heat due to conduction, convection and radiation; the remaining 24% is lost through evaporation, insensible perspiration and respiration".

                                   

                                  It would perhaps be useful if we knew exactly how much each process contributes.  Then again, nature is never a constant--like you said, things like wind and humidity greatly change the rules.  So maybe exact numbers are impossible to determine.

                                   

                                  Thanks for your reasoned discussion...Ed

                                   


                                   


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                                  hammockcamping-unsubscribe@yahoogroups.com



                                  Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

                                • David Chinell
                                  MessageSarge: Didn t mean to get you side-tracked on the reflective heat issue (though I am glad to have someone more credible than me weigh in on it). You
                                  Message 16 of 18 , Feb 3, 2003
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                                    Message
                                    Sarge:
                                     
                                    Didn't mean to get you side-tracked on the reflective heat issue (though I am glad to have someone more credible than me weigh in on it). You didn't answer my other question... How do you pack your super-wide closed-cell foam pad?
                                     
                                    Bear
                                     
                                  • Ernest Engman <ebengman@hikinghq.net>
                                    Doh, Sorry. I use a Moonbow Gearskin, so I don t roll up my pad. Instead I put the two layer part against my back and pack it like a Taco, compression straps
                                    Message 17 of 18 , Feb 3, 2003
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                                      Doh,

                                      Sorry. I use a Moonbow Gearskin, so I don't roll up my pad. Instead I
                                      put the two layer part against my back and pack it like a Taco,
                                      compression straps on the side close the wings like side panels. You
                                      can see the pics of my gearskin and get the idea at:
                                      http://hikinghq.net/gear/moonbow_gearskin.html

                                      SGT Rock

                                      --- In hammockcamping@yahoogroups.com, "David Chinell"
                                      <dchinell@m...> wrote:
                                      > MessageSarge:
                                      >
                                      > Didn't mean to get you side-tracked on the reflective heat issue
                                      (though I
                                      > am glad to have someone more credible than me weigh in on it). You
                                      didn't
                                      > answer my other question... How do you pack your super-wide closed-
                                      cell foam
                                      > pad?
                                      >
                                      > Bear
                                    • David Chinell
                                      Neeeeet. Bear ... From: Ernest Engman [mailto:ebengman@hikinghq.net] Sent: Monday, February 03, 2003 02:40 PM To:
                                      Message 18 of 18 , Feb 3, 2003
                                      • 0 Attachment
                                        Neeeeet.

                                        Bear


                                        -----Original Message-----
                                        From: Ernest Engman <ebengman@...>
                                        [mailto:ebengman@...]
                                        Sent: Monday, February 03, 2003 02:40 PM
                                        To: hammockcamping@yahoogroups.com
                                        Subject: Re: Hammock Camping Franken pad and bride of
                                        Frankenpad


                                        Doh,

                                        Sorry. I use a Moonbow Gearskin, so I don't roll up my pad.
                                        Instead I
                                        put the two layer part against my back and pack it like a
                                        Taco,
                                        compression straps on the side close the wings like side
                                        panels. You
                                        can see the pics of my gearskin and get the idea at:
                                        http://hikinghq.net/gear/moonbow_gearskin.html

                                        SGT Rock
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