Cold Hindquarters

[jackpike]

Has anyone ever successfully used foil-bubble as a sleeping pad, or for extra heat-retention in cold weather?

I'm planning a 2-nighter on the Ozark Trail for this weekend. I find that my inflatable closed-cell pad comes up short as under-body insulation (cold butt in morning) so I'm trying to DIY engineer a sleep system remedy.

I tried lining my tent floor with a mylar "space blanket." I did also use my air pad. Results were "better" than w/o mylar, but not great. Cold hindquarters remained.

Then I noticed the foil-bubble auto sun shade in the back of my car. "I wonder if I could put that under my pad." Anybody ever used this, or the foil-bubble duct wrap stuff often lauded as good "pot cozy" material?

[Patrick S]

I had a friend that used a sun reflector for a car as a sole sleeping pad. It didn't provide much comfort, but he was a hammock guy. I figured it was a common thing for "those guys."

He used it on the hard floor of a few huts some cold nights in the Whites and said it reflected almost too much heat and kept him pretty warm. He wasn't comfy, but definitely warm.

I don't know how good it would do under your pad. I thought about trying it on top, but have yet to do so.

[Jeremy Greene]

http://www.suluk46.com/products%20%20-%20P3%20PG%20Sheet.html

Above is one option for a thin ccf. Ccf is tried and true for sleeping. I think folks use the foil bubble as pot cozy because it seems easier to clean than foam. It may shape and tape easier too.

[jackpike]

That encourages me that I might be on the right trail. Thanks.

[Javan Dempsey]

I find that the mylar works better over the CCF pad, reasoning being that it's reflecting your body heat back at you before the buffer of the CCF..

Although, YMMV. Otherwise, add a walmart blue foam (open cell?) to the mix, works great for the $6 or so. I've used my ridgerest with one of these and a space blanket down below zero, although, not much below.

[Han Ngiam]

Here is something that is a little more multi-use. Get one of these and stitch on some velcro in certain areas and it can double as ground cover, a tarp or close it up where the velcro is to make it into a temp bivvy sack.

http://www.warmers.com/ItemDetails.aspx?itemid=MPIAWB&pkey=Products|Survival+Gear|SPACE+Brand+All+Weather+Blanket&pval=0|34|MPIAWB&pIds=Showcase|CategoryID|itemid

[Bob Gross]

Aluminized mylar is a waterproof and airproof barrier. It reflects most of your radiated body heat back, but radiated body heat is only a small percentage of total heat loss, typically less than 10% and varying with different body parts.

The most effective insulator traps air or vacuum, pure and simple. Look at a Thermos bottle.

Bubble-pak works a little as a cushion, but convection happens in each bubble, so it is not great as an insulator.

It is really hard to beat closed cell foam.

My rule of thumb is to take twice as much thickness of CCF for winter as for summer.
–B.G.–

[Kevin Tjaden]

Here are a couple of experiments along the same lines that I did a few years ago trying to save weight and money. In the end, I don't think I did either.

First- dollar store windshield reflector. Silver on one side, Speedy McQuuen Disney character on the other. Used alone at about 6,500 ft with a low of 36 degrees. Piled duff with the reflector on top. Did a fair job, but around 2 am it was cold and my hip bones were sore. Duff + reflector screen weighed more and took up more space than more effective solutions.

Second- Found a dollar store air mattress like you would use in a pool. Vinyl and bright pink but packed away nicely. I cut off the top section which was a pillow like structure. This gave me access to the air chambers. Cut 2.25" x 54" strips off a mylar blanket and slid them into the bottom of each air chamber. Resealed the end with heat and then glue as a second barrier. folds up to about the size of a coke can for a pad that was 22" x 56" x 2". This worked great in the places where the mylar stayed, but for about 2/3 of the pad the mylar just migrated or got balled up or otherwise wasn't where I wanted it. Where there was mylar it was almost to hot, where there wasn't it was too cold and I could never get comfortable.

Third- Using another dollar store air mattress and cutting it the same way, but this time I did two different things. I attached the mylar strips to similar strips of the thinnest climasheild insulation and very carefully spot glued the back of the climasheild before inserting. All but one chamber stayed in place. This was warm and cozy, but in the end weighed more and took up more space than similar solutions from brand name manufacturers.

Final solution, which worked as well as anything else but required a lot less work. The last dollar store mattress, uncut and still neon pink, with the Speedy McQueen windshield reflector on top and then me in a quilt. But doubling up the solution, reflector and air mattress was very space consuming so I ditched the whole effort.

I still like and use a cut-down version of the dollar store air mattress for warm weather. It, suprisingly, has survived about a dozen summer trips without deflating or popping. Doesn't offer much warmth and it is heavy by Ultralight standards (9-10 oz.)but folds flat and keeps me off the ground.

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