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  1. #1
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    Question Pad: Is insulating effectiveness the same in hammock as on the ground?

    I assume R-value is R-value but still wondering. Ground is cold but not convective like a the air.

  2. #2
    cmc4free's Avatar
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    No, not the same. A pad will allow more heat transfer when used in a hammock vs. on the ground.

  3. #3

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    Yar... both right.

    R-value is R-value.

    But convective loss is not the same as conductive.

    This is exceptionally true around freezing and under.

    Simple example: The Xtherm pad is very popular with hundreds of solid reports of using it below zero on the ground.
    I couldn't get that thing much past freezing in the air without cheating... and even with a little cheating I had trouble at 20*.
    There is one person here who used one lower... but thus far just the one who made the zero degree claim in a hammock. Even some self-proclaimed cold sleepers have claimed zero or close on the ground... warm sleepers as much as -20*.

    Probably an easy way to judge for all hammock stuff... You're insulating against 'real feel' (TM) temps or wind chill ratings rather than actual ambient air temps.
    I struggled a long time to try to get hard won and carefully beat down to minimum ground insulation systems to work in the air before finally giving up and giving in.

    I nearly always size my UQ up 20* or so beyond what is needed... and rarely use a pad outside summer or mild shoulder season conditions. (45-50* unless i have good reason)

    A top quilt is still mainly a top quilt... but in a bridge it can help to size that up too.

  4. #4
    Senior Member BillyBob58's Avatar
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    Air is quite often colder than the ground, plus there can be some wind chill to deal with. Even with the wind well blocked via tarp, there is still often at least some air movement under the hammock. So most likely, if a pad system is good for minus 40F on the ground, it won't be that warm in the air, where it will be exposed to air at whatever the temp is, and maybe moving air besides. As opposed to the probably warmer ground with zero air movement under the pad.

    As JustBill said, there is one fellow here who has- more than once, taken his TR Neoair Xtherm below zero. Used inside a single layer REI Bridge. I believe his record was minus 10 or 11F, but if mem serves he did not feel like he had reached the limit. He was quite warm except for brief periods after he had gotten up to take a leak. I think he had some challenge warming back up after getting up, but finally did.

    As far as I know, Ducttape holds the record here for pads alone, at minus 22F in a Claytor double layer hammock. But he used CCF pads and I can't remember the thickness, but it was not some ridiculous thickness, and I think he stacked pads under his torso. I think he was plenty warm. I think in his case, he prefers his quilts when it is not to cold, but switches to pads at the coldest temps.

    Quote Originally Posted by DuctTape View Post
    Subzero I use ccf pads exclusively. They are bulky, but they provide the insulation necessary for the extreme temps. Minus 22 f so far, and quite warm.
    https://www.hammockforums.net/forum/...newbie-like-me!

    I have very little experience with pads in hammocks, unless you count the open cell foam pad in the HH Super Shelter. I mostly have added a torso sized cut down WM Blue pad, added to my JRB bridge when I would get a cold back about 4 or 5 AM with unseasonably cool summer temps down south. I don't remember the temps, might have been in the 60s or a bit colder. Worked great.

    In the winter, I have stacked a torso length self inflating TR with 2.6 R value and a full length TR Ridgerest with 2.6 R value(so, theoretically 5.2 R value) to be quite toast at a hair below 20F. Definitely could have gone lower, just don't know how much. 10F? Zero? How low this would be rated for on the ground, I have no idea.

  5. #5
    Senior Member 509-T203-KG's Avatar
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    Pad: Is insulating effectiveness the same in hammock as on the ground?

    I’ve seen several people on here say that a pad is not as warm in a hammock as it is on the ground. I have not seen any of the manufacturers say it, nor have I seen any tests showing it.

    I can say that I’ve used my Therm-a-Rest NeoAir XTherm MAX with a 5.7 R-Value, in my hammock, numerous times in the 20s, teens, single digits, and to a low of -10°F, and still feel I haven’t reached the lower limit.

    One chart I’ve seen says 5.7 R-Value is good to -10. The chart printed right on the packaging for the pad indicates it could be good to -40. I have no idea if there’s a difference between on the ground or in the air, I haven’t tested it.

    Here’s a link to several tests and reports I did last winter. The last post on the thread has a link to my -10° report.

    https://r.tapatalk.com/shareLink/top...ink_source=app


    Sent from my iPhone using Tapatalk

  6. #6
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    My neoair gives me cold butt at 45.
    My insulated kylmit gets me to about the same.

    Width is important, you effectively loose a few inches between a deflated pad and the curving of the hammock. 25" wide does not work for me, and I'm a tall/slender guy. Gotta be 30" if I'm going pad alone.

  7. #7
    Senior Member BillyBob58's Avatar
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    Quote Originally Posted by LearnedHat View Post
    I assume R-value is R-value but still wondering. Ground is cold but not convective like a the air.
    It just occurred to me: maybe I would phrase it differently. Is the insulating effectiveness the same in the air as on the ground? Yes! The pad has not lost insulating value. However, it is being exposed to a bigger challenge in the air. The ground- or snow- is X degrees. THE AIR MIGHT QUITE POSSIBLY BE quite a bit colder than the ground or snow, PLUS that air can move. So, just like with an UQ, the exposed surface of the pad might approach ambient air temp faster than on the ground, as the air moves under it. So a given pad might allow you to sleep in colder temps on the ground than in the air, simply because the ground is not as cold as the air and there is no air moving under it.

    One difference I have noticed between pads and UQs: Since your top and back- in a hammock- are exposed to the same cold air, and since the air might not be as well blocked(by the tarp) on the UQ as on the TQ(assuming no UQP), obviously the UQ is going to have to be AT LEAST as warm as the TQ. Perhaps in real life even a bit warmer. However(again, assuming no UQP), if the wind is not TOTALLY blocked by the tarp, I am going to notice! When poorly blocked - say no tarp or tarp not big enough and wind switches directions- I can feel that wind go right through the shell of my UQ and noticeably drop the warmth, a lot. I feel it is easy for a 20ºUQ to be turned into a 40ºUQ if even a moderate breeze is getting to the UQ. A strong breeze could make matters even worse. Which is one reason why I have always been a fan of UQ protectors or their equivalent such as in the HH Super Shelter, which also allows me to use a smaller tarp.

    However, in my testing on windy days even with no tarp, or a high, wide tarp pitch, using a pad, I never even feel the wind. Those big gusts hit, and I brace for them, but then feel nothing. I have done this sometimes after switching from an UQ being used well above it's rating, where I was feeling every gust. When I switched to the pad, the wind was a non event.

    Now, I am NOT saying that the wind is of zero consequence with a pad. It may indeed lessen it's ultimate warmth, by sucking away whatever warmth has managed to migrate from my back to the outer surface of the pad, which I then must replace with my body heat. It probably does make a difference. But that wind can not enter into the insulation of the pad to any significant degree, blowing the warmed air right out of there. As it can so very easily do with an UQ. Unless a large tarp is well deployed, or a good UQP in place, to totally block that wind, I am going to feel it, guaranteed! And an unblocked breeze that might make things intolerable with an UQ, likely will go totally un-noticed with a pad. Assuming the pad is plenty warm enough for the air temp to start with.

    At least this has been my experience. YMMV.
    Last edited by BillyBob58; 03-28-2020 at 15:20.

  8. #8
    Senior Member BillyBob58's Avatar
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    Quote Originally Posted by chapinb View Post
    My neoair gives me cold butt at 45.
    My insulated kylmit gets me to about the same.

    Width is important, you effectively loose a few inches between a deflated pad and the curving of the hammock. 25" wide does not work for me, and I'm a tall/slender guy. Gotta be 30" if I'm going pad alone.
    What NeoAir is that? Do you happen to know the R value? Is it fully inflated?

  9. #9
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    Quote Originally Posted by BillyBob58 View Post
    What NeoAir is that? Do you happen to know the R value? Is it fully inflated?
    Xlite, r-value 3.2. It is not fully inflated, not even enough to stand upright on it's own.
    Its inflated for comfort, not full loft/insulation. In a single layer bridge, a under inflated pad is so comfortable, but a fully inflated one feels tippy, stiff and hard to stay on.

  10. #10
    Senior Member BillyBob58's Avatar
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    Quote Originally Posted by chapinb View Post
    Xlite, r-value 3.2. It is not fully inflated, not even enough to stand upright on it's own.
    Its inflated for comfort, not full loft/insulation. In a single layer bridge, a under inflated pad is so comfortable, but a fully inflated one feels tippy, stiff and hard to stay on.
    OK, thanks! That explains the cold butt at 45, along with the R value was not all that much to start with. But should be enough R for 45. A thick pad in a single layer bridge def makes them more tippy. Even a double layer still raises the center of gravity and feels less stable. A Hammock Tent 90, with it's deep pad pocket, has no such problem, the center of gravity is not raised at all. If anything, the opposite problem: if the pad is not thick enough, it won't fill the pad pocket, and I won't be in full, solid contact with the pad, and won't get full warmth. If the pad is less than 3" thick, might need something puffy on top of the pad to fill any gaps, especially in the vallieys between the baffles.
    Last edited by BillyBob58; 03-30-2020 at 10:38.

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