Feb 16, 2007 at 12:45 pm #1221880
Over my three years of backpacking, I've tried four sleeping pads. The purchase of my first sleeping pad received little thought because it was
free when I bought my first sleeping bag. It was a regular size Thermarest RidgeRest.
My next purchase was a Thermarest ProLite 3 short pad. My thinking was that it would be more comfortable than the closed cell pad. Then I bought a Thermarest Prolite 4, regular size, because I wanted my legs to fit on the pad. My fourth pad I made by trimming my RidgeRest. My thoughts had returned to weight reduction.
All four were acceptable sleeping pads for me although they varied in comfort as well as weight. I tried to quantify each pad's sleeping comfort versus its pain (carrying more weight) to see which one was my best choice.
I figured that more comfort results from increasing R-Value, Sleeping Area, and Thickness. On the other side, more pain arises from increasing the weight of the pad.
For each of my pads, I listed its R-Value, Sleeping Area, Thickness, and Weight. I made R-Value (R), Sleeping Area (A), and Thickness (T) equally weighted variables, and multiplied them to get a Comfort value (C).
Because weight (W) is such a significant factor to me, I squared the weight and then divided it into Comfort (C) to get my Comfort-to-Pain (P) ratio.
C = R * A * T
P = C / (W * W)
When I only considered comfort without regard to weight, the regular ProLite 4 was way ahead of the pack. However, when I factored in the Pain of carrying extra weight, the RidgeRest Trimmed was clearly the best choice.
Prolite 4 Reg
Grams Per Sq In 0.472
Prolite 3 Short
Grams Per Sq In 0.394
Grams Per Sq In 0.278
Grams Per Sq In 0.278
* – my original RidgeRest became the Trimmed pad so I was really glad that the untrimmed version did not do well
Product: Thermarest ProLite 4
Wt: 24 oz (680g)
Surface: 20 x 72 in (51 x 183cm)
Rolled: 11 x 4.8in. (28 x 12cm)
Thickness: 1.5 in (3.8 cm)
Product: Thermarest ProLite 3 Short
Wt: 13oz (370g)
Surface: 20x47in (51x119cm)
Rolled: 11 x 3.4in. (28x9cm)
Thickness: 1.0 in. (2.5 cm)
Product: Thermarest RidgeRest*
Wt: 14oz (400g)
Surface: 20 x 72in (51 x 183cm)
Rolled: 20 x 8in. (51 x 20cm)
Thickness: 0.625in. (1.5cm)
Product: Thermarest RidgeRest (Trimmed)
Wt: 7.4oz (210g)
Surface: 18 x 42in (46 x 107cm)
Rolled: 18 x 5in. (46 x 13cm)
Thickness: 0.625in. (1.5cm)
Cost: $0Feb 16, 2007 at 1:16 pm #1378847
@foodLocale: Colorado Rockies
Cool math. I wonder how that would work with a hammock?Feb 16, 2007 at 6:01 pm #1378895
Douglas FrickBPL Member
> I wonder how that would work with a hammock?
When I read the thread title "Painful Comfort" in relation to sleeping pads, I was thinking it would be about how painful it is to sleep on the ground. So as I see it, the 'pain' factor is zero in my hammock because I get a good night's sleep without pain.
Not quite consistent with the above calculations, but it works for me.Feb 16, 2007 at 7:09 pm #1378902
The .625" thickness of the Ridgerest will last only a few weeks in the hip area, in my experience, after which the thickness is reduced to maybe .125". There is nothing you can do to recover thickness either. I never camp on snow so even .125" is normally enough insulation, even when using a quilt so that this .125" of closed cell foam is ALL I have under me. I am 5'11" and 165 lbs, for reference.
The Ridgerest is a particularly stupid design, IMO. Those ridges look great in the store but quickly collapse in the hip and shoulder areas, and the ridges elsewhere are basically uesless. The correct way to design a closed cell pad is to double the original thickness in the shoulder and hip areas, and then rely on this doubled thickness to quickly collapse under use, and forget these ridges. The only good thing about the Ridgerest is that the foam has been "cured" somehow, so it doesn't tear as easily as the blue foam pads.Feb 18, 2007 at 9:11 pm #1379119
@bjamesdLocale: South Coast of BC
I've been using Prolite 4S pads since the 80's.
Yesterday afternoon I walked 6 miles with 3000' elevation gain, in blowing wet snow, breaking trail on snowshoes, alone. Skin-out weight 57 lbs.
I finally stopped when I couldn't see the trail markers, pitched my tent, and curled up on my new Exped DownMat 7. It's a cannonball — it weighs 32 ounces with the stuffsack. (More than any single item in my kit except my tent.) My body was so stressed that I eating made me feel sick, the cold in my boots felt like daggers cutting my feet despite no frostbite, and I couldn't slow my heart down. I finally curled up in my bag and crossed my fingers that I'd be okay until morning. I couldn't sleep from 8 pm to midnight because of adrenaline.
I then proceeded to have the best sleep I have ever had in the backcountry, ever, period. I am 180 lbs and a side sleeper, and since before my teens I have never found Thermarests comfortable. I just tolerate them until morning.
Yet last night, if it hadn't been for the blizzard burying my tent and the dampness infecting my sleeping bag due to super humidity, I could have been in my own bed.
It's the first time I haven't come back from a trip sleep deprived. I also noticed it in my performance today: despite walking until my legs were shaking and I was taking a breather every 50 steps, I was strong this morning thanks to an *amazing* nights' sleep.
I will carry the DM7 with me on every trip including poncho tarping. For me, the benefit would outweigh the weight penalty if it was another pound heavier.
If I'd had the means, I would have sprung for a Stephenson's DAM. It's much thicker, 50% warmer, and weighs only 20 ounces.
/my two centsFeb 20, 2007 at 10:50 am #1379319
Did not know if you had the reg or short, but either of them is better than my pads per my criteria…
Exped Downmat 7
Grams Per Sq In 0.564
Exped Downmat 7 Short
Grams Per Sq In 0.622
P 4.457Feb 24, 2007 at 2:00 pm #1379899
Joe ClementBPL Member
I don't care what it calculates out to…….I'm using my Insul-Mat max thermo, and sleeping like a baby. I've gotten too old to go strictly on efficiency.Feb 24, 2007 at 6:38 pm #1379933
Could not compare to others because their products don't use R-Value because…
"doesn't really work to describe the net effectiveness of an InsulMat, with coring in the body and die-cutting in the feet, or closed cell under the legs and self-inflating under your body."
Anyway, I agree with you that if you are sleeping like a baby then ignore efficiency. I was only trying to find the best of my acceptable choices considering weight.Feb 24, 2007 at 8:43 pm #1379941
Joe ClementBPL Member
Mine doesn't use coring in the body. It's an air mattress with primaloft. CAlled the Ether Thermo 6 now.Mar 1, 2007 at 6:48 am #1380553
My formula is flawed. (Note: I'm applying it to three season use only.)
This became evident to me as I compared my trimmed RidgeRest to the BMW Torsolite and realized that:
My variable for 'Area of pad ' should be 'useable area' because we are human shaped.
(The original variable still applies for blobs.)
=> A tapered pad thus will get a higher score for humans.
'R-Value' increase should be a curve (upside down 'u' shape)
R-Value increasing incrementally from zero to 3 is on the curve up, but R-Value from 3 to 6 is on the curve down
I'm not sure if I'm doing all these silly calculations so I can justify buying a TorsoLite, but I'm saving a few extra bucks as I crunch my numbers just in case the Gear Shop mood hits me.
Maybe buying gear is painful comfort.Mar 1, 2007 at 6:54 pm #1380638
No offense intended but I think you may be trying to use a mathematical formula to evaluate a qualitative feature. Being an engineer myself I always want to do exactly the same thing. It is, of course, possible to arrive at estimations through modeling. But I would imagine that takes a large study and a lot of data to really complete.
For instance, why multiply the variables? Why not sum the variables in the comfort equation and apply a larger weighting factor to weight (no pun intended). That seems a little more logical. That way you could say, "R-value, area and thickness are equally important to me with weight being twice as important as any one of those factors."
Also, are R-value, area, and thickness really equally weighted factors in determining comfort for you? I suspect not. What about other factors like pad design, stuff size, durability, extra features, etc.?
Again, not trying to criticize. I just thought I'd comment because it's something I totally see myself doing too (I've got a spreadsheet that calculates the delta weight against the delta price for buying new gear in order to prioritize what my purchases should be). I know I can tend towards compulsive thinking (that's what engineers do, right?) and I've come to a point where I've got to put aside the numerical approach and go with the qualitative "I like this the best" decision making.Mar 2, 2007 at 6:40 pm #1380815
Good points. I'm going to shift towards qualitative assessments and shelf the math.
Originally I thought the pad comparison using variables was a good way to rank their comfort. I was going to do similar calcs for my other gear. I've realized that if they're all good enough to me then I should pick the lightest choice because I already own them. But if I need to buy something, it's another story.
For example, I want to become skilled using a tarp. Now my problem is figuring how to justify something like a $207 or $270 bivy, or find a cheaper bivy, or make my own bivy. Or skip the bivy. Or do I make a bug net with a floor. There are many combinations.
Other examples, I switched from a filter to Aqua Mira. That was an easy one.
Trail runners from boots – easy.
Lighter bag/quilt – this is gonna be another tough one.
My goal, by June, is to have a respectable combination of all my gear that is really light and ideal for me. Then go for it!
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