Design Theory for Cool Weather Hammocking

[skylark]

I am trying to look at cool weather hammock camping from a design engineering perspective.

http://www.cruisenews.net/backpacking/DesignCriteria.html

I would appreciate any comments!

[neo]

I am trying to look at cool weather hammock camping from a design engineering perspective.

http://www.cruisenews.net/backpacking/DesignCriteria.html

I would appreciate any comments!

jacksrbetter covers all the bases in hammock camping if you can afford it:cool: neo


http://www.jacksrbetter.com/index_files/Products%20List.htm

[K-Man]

Jeez...Reading that gave me flashbacks to reading mechanical engineering lab test reports in college. It seems you have detailed out the causes of cold weather discomfort and the possible design solutions. Do you have any system designs that are different than what is on the market already? What are you trying to accomplish with this? I hammock camp through all four seasons using a variety of products to keep me warm and have been out in weather down in the teens. Here is my design engineering perspective on winter hammocking:

-Clark Ultralight (provides weather protection)
-WM Alpinlite 20* bag (top warmth)
-Exped Downmat 7 short (bottom warmth)
-Speer Segmented Pad Extender 2x2 (side warmth)
-sitting pad under my feet (three sections of Z-lite) (foot warmth)
-Jacket for pillow

Using those I sleep comfortably in around 15* weather. I don't like the "under pod" idea because now you do not have the "go to ground" option that using a sleeping pad allows. I think you did an excellent job in describing the issues one has to deal with when cold weather hammocking.

[Just Jeff]

Looks like a good job of laying out the issues. One point I'd be careful about, though - Under "survival", condensation is ok if managed well. If I'm inside a bag and laying on a pad, the condensation wets my bag. A wet bag isn't ok. Same if I'm wearing a jacket. So wet insulating gear isn't ok, IMO, but the condensation caused by a pad can be managed to an acceptable level for some.

[skylark]

I'm trying to learn about how to put a cool weather hammock system together. Because I am making some of the gear myself, I feel responsible to think through all the potential problems. When thinking about it, I was never sure if I had covered all the considerations, so I decided to try to put them down on paper as a checklist. Probably a lot of the comments seem obvious, but the point is to make sure that they are all listed. It also helps as a frame of reference when discussing a hammock system with others.

The result of this exercise should be a gear list that works as specified, and the ability to consider more lightweight options in the future. I should point out that I have not yet successfully hammock-camped in cool weather and achieved comfort status, I experienced too much condensation. So I am very motivated to figure out how to do it right.

Good point about the going to ground option. In case of gear failure, that could be a lifesaver.

I will have to look at when condensation is OK (for example, an hour hike out to the car, or looking forward to a dry sunny day to dry the gear) and when it is not OK (cold front coming in). Also how much is acceptable.

[peter_pan]

I'm trying to learn about how to put a cool weather hammock system together. Because I am making some of the gear myself, I feel responsible to think through all the potential problems. When thinking about it, I was never sure if I had covered all the considerations, so I decided to try to put them down on paper as a checklist. Probably a lot of the comments seem obvious, but the point is to make sure that they are all listed. It also helps as a frame of reference when discussing a hammock system with others.

The result of this exercise should be a gear list that works as specified, and the ability to consider more lightweight options in the future. I should point out that I have not yet successfully hammock-camped in cool weather and achieved comfort status, I experienced too much condensation. So I am very motivated to figure out how to do it right.

Good point about the going to ground option. In case of gear failure, that could be a lifesaver.

I will have to look at when condensation is OK (for example, an hour hike out to the car, or looking forward to a dry sunny day to dry the gear) and when it is not OK (cold front coming in). Also how much is acceptable.

Skylark,

You don't have to be a lone explorer on this issue there are tons of information on staying warm in hammocks in the WB archives... that said, of course you should test your approach for your own conclusions.

It is nice to see the "engineerig" approach to listing issues and collecting the data...thanks for giving it some thought...look forward to seeing your test results.

Pan

[Fiddleback]

First on the list...collect data. This or any other design question cannot be answered by pure theory...empirical data is necessary. Experiment in the backyard or other locales but not on the trail or far from an easy bail out.

Early on, after the range of conditions is determined, you can set criteria. What is 'cool' when designing a cool weather hammock? I've seen posts from hammock hangers that were cold at lows of 50-60° while others never experience night time temperatures that warm. FYI, my definition of 'cool' is 32-45°. But I live in western Montana, sleep with the windows open nearly six months out of the year, and set the house temp to 61° the rest of the time.:sun

Hammock sleeping system factors important to me; lightweight, comfortable, warm at 10° below anticipated temps, ease of use (including setup, take down & packing), alternative use/set up (going to ground, one-tree hanging, sleep system during daytime), weather proofness (wet and wind), ventilation (both for moisture/condensation and cooling in summer), cost, characteristic of materials, (i.e., does it dry quickly? is it easy to clean? does it hold up to trail use/abuse?), environmental impact (damage to flora, visual impact, consideration of material used, etc.).

I'm pretty impressed with hammocks:) . But I have to admit that on the trail I've only used a Hennessy and even then I don't have many nights in it. I'll be interested in following any project that approaches hammocks with a fresh viewpoint.

FB

[hammock engineer]

Jeez...Reading that gave me flashbacks to reading mechanical engineering lab test reports in college.


Now I know I have been in school to long. I didn't notice anything overly technical until I read your post.

[gdwelker]

The weight of the system should be a concern. As we are both engineers, it is always good to remind ourselves of the "closed design univerise paradigm" - too many times we work so hard to design and optimize a certain piece of equipment that we forget to look outside of the design universe we put ourselves in.

In this case, yes, you can design a hammock system to keep you warm in almost any condition, but how does the hammock system solution compare to other non-hammock solutions that do the same function?

In particular relation to hammocks and cold temps, the weight and volume of many of the systems currently available do not compete favorably with other cold temp protection sleep systems out there - like tents, bivys, bag and pad, etc.

You may want to consider a design parameter that limits the system weight of the hammock system to equal or less than that of other cold temp sleep systems.

[Just Jeff]

In particular relation to hammocks and cold temps, the weight and volume of many of the systems currently available do not compete favorably with other cold temp protection sleep systems out there - like tents, bivys, bag and pad, etc.

Well, in absolute terms this is probably true. If all you're carrying is a torso-length CCF pad, a 5x8 tarp and a quilt, you can get lighter than a hammock for a given temp. But how many hikers actually hike like that? I know there are some, but most prefer a bit more comfort in the pad, some bug protection, etc. Even the lightest are in a tarptent weighing about 2 lbs...just what a HH weighs.

And if you can manage the condensation, you could use the same CCF pad and quilt in a hammock as you would in a tarp, so now it's equal. Actually, your quilt can be much narrower so that should save a few ounces over the tarptent setup.

And there are only 2-3 (pretty expensive) waterproof bivies under two lbs...so bivies don't really offer any advantage, either. Also, many people hiking with small tarps also use a DWR bivy...add in another 6-10 oz.

My point isn't that hammocks are the lightest option. But if you compare apples to apples in terms of comfort and features, they do compare favorably with other systems. But like everything else, there are trade-offs...I could save 6 oz by carrying a CCF pad, but I choose to carry the extra weight of my JRB quilts because, for me, the comfort is worth it.

[Rifleman]

I am trying to look at cool weather hammock camping from a design engineering perspective.

http://www.cruisenews.net/backpacking/DesignCriteria.html

I would appreciate any comments!

KISS, aka cannon of Parsimony.
Utilize a 'Neat Sheet' w/o the weights (7 oz) spread out in the hammock. This will achieve two things. One, when sprayed with fabric water proofing agent the neat sheet will act as a semi-vapor barrier. Two, the neat sheet is washable & will assist to keep the hammock clean (Would you sleep on your mattress at home w/o a sheet?).
Next utilize a 3/8" thick by 20" wide by 36" long piece of closed cell foam. I use the Wally World blue pad (3-4 oz) --inexpensive & effective. Place this cross-ways in the hammock. It will protect your shoulders from 'hammock wrap.' It can be used as a sit-pad before turning in. In many ultralight packs it can be used as a frame sheet also.
Utilize a Pacific Outdoor Equipment InsulMat Max-Thermo sleeping pad (22 oz) on top of the blue pad.
http://www.backcountry.com/store/POE0016/c3/s17/Pacific-Outdoor-Equipment-InsulMat-Max-Thermo-Sleeping-Pad.html
The POE InsulMat works in a hammock & on the ground/shelter floor. Sooner or later you will be forced to go to ground. If you perspire from being in contact with the Insulmat the channels between the chambers will keep the perspiration away from you.
This system along with the 20 deg. bag used as a quilt, polypropolene long underwear,smartwool socks, and a fleece beanie should keep you warm to 20 deg's (unless you are a cold sleeper). Adequate tarp placement and cover is a must. :-?
R.

[Nagal Logute Iyapa]

I would add an external net on the hammock that could be stuffed with hardwood leaves or dry pine needles. This gives you a squirrel's nest perspective and minimizes your backpack weight which is always an issue. After using the leaves as an insulator for the night, you return them to the forest. It makes ergonomic and ecological sense.

[neo]

I would add an external net on the hammock that could be stuffed with hardwood leaves or dry pine needles. This gives you a squirrel's nest perspective and minimizes your backpack weight which is always an issue. After using the leaves as an insulator for the night, you return them to the forest. It makes ergonomic and ecological sense.

that will work if you have dry leaves:cool: neo

[generoll]

This whole topic of temperature and hammocks has me totally confused. I bought a HH on a whim when I saw one of EBay and am trying to decide whether or not to take it instead of my MegaMid when I do me next section hike in March. Lots of people have come up with very creative solutions and then when I get to the end of the story it seems they are happy to sleep warm at 30 degrees. Since I'm fairly confident that I'll encounter temps below that, I'm still uncertain just how wise it is to take a hammock. Some folks have suggested just moving to a shelter when it gets cold, but that tends to defeat the whole idea, in my opinion. I think that anyone hiking should be prepared to sleep out in any conditions, shelters are a bonus, not an entitlement.

Most of the solutions seem to suggest that if you hold your breath right and turn three times around and then don't move once you're in the hammock, that all will be well. Has anyone actually used a hammock in below freezing temperatures with wind, rain or snow and found it satisfactory?

I do love the comfort of a hammock, but I hate waking up in the wee hours with my butt freezing.

[hammock engineer]

Risk made it to well below zero with the wind chill. He said that he was comfortable the whole time. He lays it out pretty well on his web site.

http://www.imrisk.com/hammock/ultrahammock.htm

[peter_pan]

This whole topic of temperature and hammocks has me totally confused. I bought a HH on a whim when I saw one of EBay and am trying to decide whether or not to take it instead of my MegaMid when I do me next section hike in March. Lots of people have come up with very creative solutions and then when I get to the end of the story it seems they are happy to sleep warm at 30 degrees. Since I'm fairly confident that I'll encounter temps below that, I'm still uncertain just how wise it is to take a hammock. Some folks have suggested just moving to a shelter when it gets cold, but that tends to defeat the whole idea, in my opinion. I think that anyone hiking should be prepared to sleep out in any conditions, shelters are a bonus, not an entitlement.

Most of the solutions seem to suggest that if you hold your breath right and turn three times around and then don't move once you're in the hammock, that all will be well. Has anyone actually used a hammock in below freezing temperatures with wind, rain or snow and found it satisfactory?

I do love the comfort of a hammock, but I hate waking up in the wee hours with my butt freezing.

BTW, I've used my hammock many times below freezing, in snow, sleet etc and always been comfortable....And I do it with ultralight loads and packs well under 3000ci...have not been to ground in near 30 months now.

Pan

[Fiddleback]

It takes an effort to stay warm...but it's not a really huge effort. However, all other things being the same, it's cooler in a hammock than on the ground. But all other things being the same, it's also a whole lot more comfortable in a hammock than on the ground:clap . The main thing is to not find out you're gonna freeze your butt with your set-up while on the trail. Find out at home...experiment in the backyard or wherever you can set up with an easy bail out.

I've relatively few nights in my Hennessey but all but one was below freezing. The only time I used a cover instead of dressing in cold weather clothing was when we expected and got crappy weather. It snowed, sleeted, rained, and came down in any combination of the three. It blew all the time. I used my bag as quilt and was so toasty that I was almost hot. I awoke late to trailmates who weren't happy about fixing breakfast while listening to my snoring.:D

I've done mid-20s with a pretty minimal system. Getting down to truly cold temps it just a matter of putting the right combination of gear together and testing it out. Lot's of systems will keep you warm; find one that's simple, light, and packable. This and other forums are a tremendous help.

FB

[Just Jeff]

Many folks have been below freezing, and several have been below zero. I've been in freezing rain, blowing snow, high winds, etc. Only once did I bail, but the winds were well over 100mph.

The only reason it seems confusing is because it's all new and people are still experimenting. If you want easy, just get an underquilt or a pad/SPE and you'll be good. If you want to be sure you're good for well below freezing, get a thicker underquilt (like JRB's ORM) or put more pads in the SPE. Patrick will even customize the KAQ with more insulation if you want. Easy.

[generoll]

When I mentioned freezing my butt, I was speaking literally. I've tested my hammock a couple of times with a basic 3/8" CCF and both times woke up in the morning with my backside cold. I'm just wondering what sort of practical modification or addition I could come up with (and fit into a pack) that would extend the comfort range into the 20s. Most of the bottom covers that I've seen and corresponded about seem to think that 30 degrees is pushing the limits.

[Just Jeff]

1. ORM should do 20s since the Nest does 30s. Or use two underquilts...they pack down small.

2. Get a thicker CCF pad, or an additional torso pad. A SPE will hold them together, provide side coverage, and not add appreciable weight (like 3 oz or so) if you stuff extra clothing into the wing pockets.

3. KAQ with the extra layer of Primaloft should easily get you to 20s.

4. Get a PeaPod. With a torso pad and top quilt, you should easily get to the 20s.

Considering the temps, none of those will add much volume to your pack. It'll still be more than a tarp setup...It's up to you if the comfort is worth the extra few ounces and a bit of volume.

It's really no more complicated than deciding between tents, tarps and tarptent features; pad sizes, shapes and materials (or inflatables, insulated inflatables...), sleeping bag designs, materials, features; etc.

But it's not for everybody...plenty of folks just don't think it's worth the effort to hammock in winter. And that's ok...more trees for me!

[skylark]

My experience with closed cell pads at +/- 30F has been the same, a cold back, which seems to be due to condensation and maybe compression of the pad. I am hoping that an underquilt will solve both of these problems.

Another problem that I had was compression of my top quilt on the sides by the hammock, leading to chilled shoulders and hips. This is another problem that should be fixed by an underquilt.

I haven't tried an underquilt yet, but that will be my next test. The closed cell pads just did not do it for me. They provided survivability but not comfort at 30F.

There may be some things that I could do to improve on placement of the closed cell foam pads, but that won't help with the condensation issue.

[SteveJ]

When I mentioned freezing my butt, I was speaking literally. I've tested my hammock a couple of times with a basic 3/8" CCF and both times woke up in the morning with my backside cold. I'm just wondering what sort of practical modification or addition I could come up with (and fit into a pack) that would extend the comfort range into the 20s. Most of the bottom covers that I've seen and corresponded about seem to think that 30 degrees is pushing the limits.

I agree that a single 3/8" CCf pad won't cut temps much below 40. I've been into the low teens, with high winds, with a 3/8" CCF pad and a TR guildelite. It's a little tricky getting in - but not too bad. And once I lay back in my hammock, I find that I don't wake up 'till morning or I need a bio break..... How long's it been since that happened while on the ground?! This solution has worked for me because it's cheap, light and uses stuff I already have.

[generoll]

sounds reasonable. and like you, i already have those things. might try out my new Big Agnes instead of my TR, but if i can fit the CCF on the outside of my pack it might just make sense.

[swede]

Like stated before, experiment on over-nighters close to home. Take more sleeping gear than you would while hiking and find your combination. I have spent 8 nights this winter camping on nearby coastal barrier islands where the wind always blows. I found adding a windshield reflector crossways under my thermarest at the shoulders helped with the cold,and a fleece stadium blanket added versatility to my bag. A windshield reflector weighs a few ounces, and is all I need as a pad in milder temps, and the stadium blanket easily fit with my bag into it's stuff sack. My HH setup kept me dry and warm while my ground dwelling buddies, well you know.;)