Nov 18, 2009 at 10:25 am #1242269
If I put an uninsulated air mattress on top of a CCF pad will the resulting insulating value increase, decrease, or remain the same…?
To be specific, I'm wondering if I pair my new KookaBay mummy cut uninsulated air mattress (60" x 2.5") with a full length 3/8" CCF pad if it will be warm enough for winter conditions in the White Mountains of NH.
For reference, for years I used a single full length ThermaRest for these conditions without any trouble. I think it was 2" thick or maybe 1.5" Whatever the original old style mattress was before they started offering all kinds of options.
I could go with a thicker CCF pad as well, I'm just not sure what's feasible and if the uninsulated air mattress actually increases or decreases whatever insulating value the CCF provides.Nov 18, 2009 at 10:56 am #1546117
@beepLocale: Land of 11, 842 lakes
You won't gain any warmth worth mentioning from an uninsulated air mattress (unless it's a NeoAir which is technically "uninsulated"). You'd be better off adding a layer of CCF for an inexpensive solution.Nov 18, 2009 at 11:07 am #1546120
I am going to add a CCF for sure. What I'm wondering about is the insulating value of the combination.
I'm considering the 3/8" CCF pad from SULUK 46 and my Kookabay air mattress.
Neither one would be enough alone but I'm wondering if the combo would be sufficiant or if I need a beefier CCF pad.Nov 18, 2009 at 11:33 am #1546134
@richard295Locale: San Francisco Bay Area
An un-insulated air mattress provides a maximum R-Value of .95. You need ~ R-Value 5 to be thermo neutral (not reduce your core temp) to 32F ground. The R-Values are additive for pads and so the CCF pads you select need to total 5 – .95 = 4.05.
The sophisticated construction RidgeRest Deluxe provides R-Value 3.1 with only .75" thickness. The pedestrian blue CCF pads provide ~ R-Value of 3.6 per inch. If you used your air mattress in combination with a RidgeRest Deluxe, then you would need to also augment this combination with a ¼” CCF to be thermo neutral.
The original Therm-a-Rest is 1.5" thick and has an R-Value of 5.Nov 18, 2009 at 11:53 am #1546143
Thanks so much – this is more precise info than I could have hoped for.
I have what is possibly a dumb couple of follow-up questions:
* Do I need my sleeping pad system to be thermo neutral to stay warm since my body will continue to generate some heat throughout the night?
* Is there any way to calculate the R-Value the down in my sleeping bag will add to the system, or is that negligable since it's crushed under my body weight? (My bag has roughly 3.5" to 4" of loft on each side.)
My guess is I need to shoot for the full 5 R-value with ground insulation alone, but I thought I would ask.
JohnNov 18, 2009 at 12:03 pm #1546147
John, ideally you would want the pad to be thermo-neutral, otherwise you'll spend the night losing the heat you produce to the ground. The insulation in your bag under you doesn't add anything to under-insulation. The reason it's there is so that when you roll over on your side you still have insulation.
You'll find people on this site who use absurdly low R-values for winter trips. I've tried it and never slept well. Stick with Richard's advice.Nov 18, 2009 at 1:07 pm #1546173
wouldn't the ccf on top of the air pad be warmer than on the bottom as the air in the pad is still cold?
-TimNov 18, 2009 at 5:55 pm #1546243
Richard, thank you for all the data you provide. This thread plus the recent ones on down jackets are really helpful in getting a couple sticking points in my winter gear list cleared up.
My winter sleeping pad system is one I've been trying to figure out. Last winter in the Sierra's, used a Thermarest Z-Lite (r-value 2.2) on top of a 3/8" blue CCF from REI (r-value 1.35, if my math is right). Now I understand why I why still chilly in my 15 degree bag.
This winter, I was originally considering an insulated pad, but am having trouble justifying the expense for something I'll use for maybe 3-4 trips a year.
I have a NeoAir short. If the manufacturer's claimed R-Value of 2.5 is accurate, I might be okay with a system of the Z-Lite underneath it and my GG 1/8" Thinlite (r-value .45) on top for a cumulative r-value of 5.15.
I'm hoping this works as I'd rather used what I already have, and the total weight is ~23 oz, lighter than an Exped Downmat, and I'd need to bring the CCF for sitting anyways(And as an emergency backup in case of a leak).Nov 25, 2009 at 4:07 pm #1548126
I found this when I did a search trying to find the R Value of my BA Clearview Pad; just thought it was relevant to this topic and somewhat helpful.
=)Happy Winter Travels-Stay WarmNov 25, 2009 at 4:36 pm #1548136
Using inflatable mats I like to adjust the air so my hip and shoulder are almost touching the ground. That gives the best padding. In winter though it doesn't work if you just have the inflatable- hip and shoulder get super cold sleeping on snow.
Although bulky, I use a full-length Ridge Rest under my 48" self-inflating mat. This seems to be a good combination and reasonable weight. I would think that with an uninsulated air mattress (even the Neo-Air), you would be better with foam on top.
Snow will quickly warm up to 32F, but obviously never go above that as it uses heat to melt. Frozen ground may be much colder at first but if it's dry it may warm up- a bed of dry pine needles makes some good insulation. Frozen mud will be the worst of all worlds- hard, lumpy, and bone-chilling cold.Nov 25, 2009 at 4:46 pm #1548138
on second thought…..
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