Loading ...
Sorry, an error occurred while loading the content.

Re: Hammock Camping Franken pad and bride of Frankenpad

Expand Messages
  • 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 1 of 18 , Feb 2, 2003
    • 0 Attachment
      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 2 of 18 , Feb 2, 2003
      • 0 Attachment
        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



        Your use of Yahoo! Groups is subject to
        http://docs.yahoo.com/info/terms/
      • 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 3 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 4 of 18 , Feb 2, 2003
          • 0 Attachment
            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 5 of 18 , Feb 2, 2003
            • 0 Attachment
              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

               


               


              To unsubscribe from this group, send an email to:
              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 6 of 18 , Feb 3, 2003
              • 0 Attachment
                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 7 of 18 , Feb 3, 2003
                • 0 Attachment
                  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 8 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
                  Your message has been successfully submitted and would be delivered to recipients shortly.