Field Test: Semi-Garlington Insulator

[FLRider]

Where: Area 05 (front yard).
When: Last night, 02:00 to 03:45.
Conditions: High of 46* F, dropping to a low of 44* F, light and variable wind (< 5 mph), no humidity to speak of.
Top Insulation: Poncho liner made into a top quilt by tying foot-end ties together as well as mid-point ties to make a footbox.
Clothing: Nike DriFit polyester t-shirt, nylon/spandex compression shorts underwear, nylon/spandex running shorts, thick acrylic sleeping socks, poly/cotton baseball-style hat.
Result: Unsatisfactory; I was cold.

I slept cold last night for a couple of hours, testing out the limits on my Garlington insulator. I suspend a poncho underneath my DIY hammock using Velcro and stuff a crumpled space blanket into the resulting airspace. I show it off at about 8:35 in this video:



The temperature when I went to bed was 46* F, according to my new AcuRite thermometer that I picked up at WallyWorld. I was well-fed (an individual-sized pizza at work and a pair of Reece's Peanut Butter Cups right before bed), sober, and hydrated (0.5 L an half-hour before bed).

I was cooler than I like on my back, but not cold enough to keep me from sleeping. I fell asleep fairly easily, despite the normal night noises of my neighborhood.

About two hours later (03:44 by my watch), I woke cold. Uncomfortably cold, to the point where I could tell that I wasn't going to be able to get back to sleep.

Rising, I checked the thermometer, seeing that it said 44* F. I hadn't realized that two degrees would make that much difference, but...

I now know that, for me, my Garlington lash-up is good to about 45* F. Below that, and it won't be sleepable. My comfort level with it is about 50*; I already knew that from field testing. However, I was wondering where my hard limit for the night with it would be, and that appears to be 45* F.

It's always worth testing your gear before you go out!

[BillyBob58]

Interesting test, FLRider! A GI is really kind of what a HHSS is a version of, although a custom fit and way more expensive version including an OCF pad that molds around your body.

Your table shows a PL as top insulation and I see no mention of bottom insulation? Did you mean the PL is the UQ? Or was it 2 PLs one for TQ another for UQ?

As for such a big dif when the temps dopped only a couple of degrees, could it be that your metabolism slowed down as you slept, plus the cumulative heat loss after 2 hours?

But, I have no idea what kind of insulation the PL has. So I don't know if cold at this temp is a good result or bad?

I would expect to be warmer than that with the HHSS's OCF pad and sil-nylon UC even with out the space blanket, though maybe with some condensation. At least I have occasionally slept at about those temps with no SSB with no problems, some times with condensation, sometimes not. And would expect to be way warmer with the SB. Do you think a PLs insulation should be comparable to an HHSS OCF pad plus UC, or would you expect it to be less?

How about fit? Was it snug enough without being too tight?

[FLRider]

Interesting test, FLRider! A GI is really kind of what a HHSS is a version of, although a custom fit and way more expensive version including an OCF pad that molds around your body.

Your table shows a PL as top insulation and I see no mention of bottom insulation? Did you mean the PL is the UQ? Or was it 2 PLs one for TQ another for UQ?

As for such a big dif when the temps dopped only a couple of degrees, could it be that your metabolism slowed down as you slept, plus the cumulative heat loss after 2 hours?

But, I have no idea what kind of insulation the PL has. So I don't know if cold at this temp is a good result or bad?

I would expect to be warmer than that with the HHSS's OCF pad and sil-nylon UC even with out the space blanket, though maybe with some condensation. At least I have occasionally slept at about those temps with no SSB with no problems, some times with condensation, sometimes not. And would expect to be way warmer with the SB. Do you think a PLs insulation should be comparable to an HHSS OCF pad plus UC, or would you expect it to be less?

How about fit? Was it snug enough without being too tight?

The poncho liner is the top insulation; it's good for me down into the mid-thirties before supplementation, assuming a longsleeve baselayer, shorts, puffy socks, and a watch cap (so, the only difference is the longsleeve and the hat from what I used last night; what I was wearing last night would be good down to about 40* with just the liner as a top quilt). This also presumes decent under insulation, which was what failed last night.

The under insulation was the Garlington insulator; that's all. I'd been using a sew-'em-up PLUQ over last "winter", and I find that it's good for me down to about 25* F (see here for details) with my normal clothing and top insulation at that temp. I'm trying to shed weight as much as possible though, and the Garlington has become my summer insulation (so, anywhere from March to October down here), shedding a good pound and three-quarters or so from my pack during those months.

It's entirely possible that it was due to my metabolism and cumulative heat loss, yes. However, when I say that I was cold, it wasn't, "I have a little chill; I could get up, walk around, warm up a bit, and go back to bed". It was, "Yeah, I'm not going to be able to sleep the rest of the night. I'm pretty freezing right now."

Which is why I did the testing in my front yard; I wanted somewhere to bail if things turned out to be colder than I'd thought. I was expecting an uncomfortable night, since I was testing the low end of survivability with this under insulation rather than its comfort zone. However, the cold I experienced was farther out than merely uncomfortable; it was not something that I could sleep through, even fitfully.

As to the HHSS vs. a PLUQ, I'd expect that in terms of raw warmth (i.e.: no wind, no precipitation, low humidity) that a no-sew PLUQ and the SS without a space blanket would perform about the same. I'd also expect that the SS would perform better in wet, blowing weather; while the PLUQ would perform better at high humidity without precipitation or wind.

I would also expect that the HHSS with a space blanket would perform about the same as a sewn-up PLUQ with average added insulation (I'm assuming InsulBright or a layer of IX with the proper darts here) in terms of raw warmth. The HHSS should perform better in wet, windy weather; while they should be about at a draw for high humidity, since the space blanket will act as a vapor barrier to prevent the OCF pad from becoming soaked.

As to fit, it works almost perfectly. I still need to add Demostix-inspired draft skirts to my hammock to close up the ends of the poncho (since I used OmniTape [well, the generic knockoff of it, anyway] as a closure system for the poncho, it doesn't grip quite well enough at the ends for the shock cord there to not be able to pull it away from the hammock body when I shift position)--and the ends of the modular underquilt that I'm designing. Once I do that, it should seal up nicely.

There'll be changes on the whole thing as I get time, inspiration, and funds. One thing at a time, though...

[BillyBob58]

The poncho liner is the top insulation;..... This also presumes decent under insulation, which was what failed last night.

The under insulation was the Garlington insulator; that's all... I'm trying to shed weight as much as possible though, and the Garlington has become my summer insulation (so, anywhere from March to October down here), shedding a good pound and three-quarters or so from my pack during those months.

OK, now I see- you were not trying to rig up a Poncho Liner as a GI, but simply the poncho alone, with space blanket thrown in. You used a "crumpled" sb. Was the SB crumpled up in some kind of sack? ( I have done that to augment a HH Super Shelter ) or was it just laid in the poncho under the hammock?

It's entirely possible that it was due to my metabolism and cumulative heat loss, yes. However, when I say that I was cold, it wasn't, "I have a little chill; I could get up, walk around, warm up a bit, and go back to bed". It was, "Yeah, I'm not going to be able to sleep the rest of the night. I'm pretty freezing right now."

Got you, and been there, done that on my 1st night ever in a hammock. Went to sleep exhausted and feeling OK in my HHSS, and only partly inside my sleeping bag which I could not get into. All that thrashing trying to get inside it ( remember, it was my 1st night and I had not yet found HF ) had probably contributed to my exhaustion, and I had actually ( unknown to me in that dark cave ) managed to rotate the hammock so that the HH pad and bottom entry was above me. Which I discovered several hours later when I woke up shivering my teeth out! Then had to fight my way out of the hammock, thought for a while I was going to have to yell for help. Anyway, coooold! But, I suspect I had a lot more temp drop from bed time to shiver time than you did. From the high 30s or 40s all the way to 22F. While you just had a couple of more degrees, and yet you got very cold. Interesting yet again!

Which is why I did the testing in my front yard; I wanted somewhere to bail if things turned out to be colder than I'd thought. I was expecting an uncomfortable night, since I was testing the low end of survivability with this under insulation rather than its comfort zone. However, the cold I experienced was farther out than merely uncomfortable; it was not something that I could sleep through, even fitfully.

As to the HHSS vs. a PLUQ, I'd expect that in terms of raw warmth (i.e.: no wind, no precipitation, low humidity) that a no-sew PLUQ and the SS without a space blanket would perform about the same. I'd also expect that the SS would perform better in wet, blowing weather; while the PLUQ would perform better at high humidity without precipitation or wind.

I would also expect that the HHSS with a space blanket would perform about the same as a sewn-up PLUQ with average added insulation (I'm assuming InsulBright or a layer of IX with the proper darts here) in terms of raw warmth. The HHSS should perform better in wet, windy weather; while they should be about at a draw for high humidity, since the space blanket will act as a vapor barrier to prevent the OCF pad from becoming soaked.

As to fit, it works almost perfectly. I still need to add Demostix-inspired draft skirts to my hammock to close up the ends of the poncho (since I used OmniTape [well, the generic knockoff of it, anyway] as a closure system for the poncho, it doesn't grip quite well enough at the ends for the shock cord there to not be able to pull it away from the hammock body when I shift position)--and the ends of the modular underquilt that I'm designing. Once I do that, it should seal up nicely.

There'll be changes on the whole thing as I get time, inspiration, and funds. One thing at a time, though...

Sounds like you have some serious research going on! I'm sure the results will be worth it.

[DuctTape]

To benefit form a GI, you need the garbage bags. A crumpled space blanket doesn't do much just tossed into the poncho as you discovered.

The next test should be the following: Rig the poncho like before. Take 2 large garbage bags, the largest volume you can find. Open the bags and allow just enough air in, so that when you tie them closed, they are only a few inches lofted. Put the crumpled space blanket in one or them. Place the bags in the poncho with the space blanket one at your torso and the other towards your legs (or use two with SB's). test again.

[FLRider]

OK, now I see- you were not trying to rig up a Poncho Liner as a GI, but simply the poncho alone, with space blanket thrown in. You used a "crumpled" sb. Was the SB crumpled up in some kind of sack? ( I have done that to augment a HH Super Shelter ) or was it just laid in the poncho under the hammock?

It was just crumpled into the poncho. I took it, spread it out to about 2/3rds its length and then crumpled it up until it was ~2 inches high and at about 2/3rds its total width. It seems to hold a small amount of dead air in there, making for some insulation (not much, but enough to get me into the low-to-mid-fifties comfortably).

Got you, and been there, done that on my 1st night ever in a hammock. Went to sleep exhausted and feeling OK in my HHSS, and only partly inside my sleeping bag which I could not get into. All that thrashing trying to get inside it ( remember, it was my 1st night and I had not yet found HF ) had probably contributed to my exhaustion, and I had actually ( unknown to me in that dark cave ) managed to rotate the hammock so that the HH pad and bottom entry was above me. Which I discovered several hours later when I woke up shivering my teeth out! Then had to fight my way out of the hammock, thought for a while I was going to have to yell for help. Anyway, coooold! But, I suspect I had a lot more temp drop from bed time to shiver time than you did. From the high 30s or 40s all the way to 22F. While you just had a couple of more degrees, and yet you got very cold. Interesting yet again!

Sounds like you have some serious research going on! I'm sure the results will be worth it.

Yeesh...not sure I'd go back to hammocks after a first night like that! (Then again, I might; I'm pretty stubborn.) But, now I know where my survivability range is for this particular form of insulation--don't plan on using it when the forecast calls for anything lower than 55* F (I always assume that meteorologists are going to get it wrong by ten degrees).

To benefit form a GI, you need the garbage bags. A crumpled space blanket doesn't do much just tossed into the poncho as you discovered.

The next test should be the following: Rig the poncho like before. Take 2 large garbage bags, the largest volume you can find. Open the bags and allow just enough air in, so that when you tie them closed, they are only a few inches lofted. Put the crumpled space blanket in one or them. Place the bags in the poncho with the space blanket one at your torso and the other towards your legs (or use two with SB's). test again.

See, I agree that the sealed container (trash bag) will work much better than just crumpling the blanket into my poncho (it's a true dead air space rather than just a restricted air space like you get with some movement through the ends of the poncho). However, I don't carry a trash bag on the trail, and my stuff sacks are much too small (with the exception of the one attached to my hammock) to cover more than a tiny area of my back. So, I was just searching for the low end of my current lash-up.

I have found that simply crumpling the space blanket into the poncho creates dead air space--not much of it, and it isn't quite as convection-free as I'd like--enough to keep me warm on the bottom down into the low-to-mid-fifties. For most folks, I wouldn't recommend that particular approach below sixty; I'm a pretty warm sleeper. But, it works for me down here for the majority of the year, at nothing more than a ~4 oz weight penalty.