Therm-a-rest Observation

[Hulk]

Last weekend i noticed something. Here's what gear i was using. HH hammock and super shelter, with space-blanket on top of the HH pad. Bag Agnes Lost Ranger 15* down bag with therm-a-rest "self inflating" pad. I had the Therm-a-rest pad firmly inflated. The temps were mild in the 60's, after a half hour of shivering..yes shivering in a 15* bag, knowing i should be toasty, i reached for the mattress valve and opened it. Thus deflating the mattress. Within minutes of deflating the mattress i was baking in the bag and started removing layers and eventually unzipped the bag to cool off.

Anyone else experience something similar, and why would this happen?

[Hawk-eye]

That's really sort of strange sounding to me ... hard to say unless you were camped over an Indian burial ground?

Only explaintion that comes to mind is maybe it was somehow creating air flow under you but at 60 degree temps ... even that sounds strange. I've used my TR before without all the other and had no problems ... wasn't firm the way I used it back then. Never tried it fully inflated in a hammock.

[Irvingdog]

You eventually warmed up your bag?

[Trooper]

I've found this to be true, but not as much of a contrast as you describe. If the pad is full and firm it reduces the contact area with your body because they are designed to lay on a flat surface. The partially inflated pad molds to the body and hammock better, increasing contact and warmth. A partially inflated pad is also easier to keep underneath you.

[Hulk]

I've found this to be true, but not as much of a contrast as you describe. If the pad is full and firm it reduces the contact area with your body because they are designed to lay on a flat surface. The partially inflated pad molds to the body and hammock better, increasing contact and warmth. A partially inflated pad is also easier to keep underneath you.

Trooper what you say does make sense, considering the Big A bag has absolutely no insulation. Now my understanding if correct, is that therm-a-rest's achieve some of there R rating from loft when they are inflated. While in a hammock they seem to be more effective defeated or partially deflated, i wonder how much r value is getting lost by deflating?

[Trooper]

Trooper what you say does make sense, considering the Big A bag has absolutely no insulation. Now my understanding if correct, is that therm-a-rest's achieve some of there R rating from loft when they are inflated. While in a hammock they seem to be more effective defeated or partially deflated, i wonder how much r value is getting lost by deflating?

I'm not sure how much R-value is lost but I doubt much is lost if you keep it partially inflated. The foam will expand which gives you the loft and the right amount of inflation will keep you from compressing it too much. The trick would be finding that magic amount of inflation.

The Hennessy OCF pad is quite thin and works remarkably well. But, because it isn't supported by the inflated air it must be placed under the hammock or your body would compress it. I'd say a little foam can do wonders.

Of course, this is only my theory and empirical evidence...Just because the rooster crows, doesn't mean it causes the sun to rise.

[alphaqlater]

Perhaps the pad was conforming to your bottom more as it was deflated to act as a better vapor barrier.

[fred1diver]

actually you are better no getting the mattress get to full even on solid ground, your body weight will stiffen the mattress when you lie on it.
FRED

[edwat72]

Ya, that pad is nice..

Last weekend i noticed something. Here's what gear i was using. HH hammock and super shelter, with space-blanket on top of the HH pad. Bag Agnes Lost Ranger 15* down bag with therm-a-rest "self inflating" pad. I had the Therm-a-rest pad firmly inflated. The temps were mild in the 60's, after a half hour of shivering..yes shivering in a 15* bag, knowing i should be toasty, i reached for the mattress valve and opened it. Thus deflating the mattress. Within minutes of deflating the mattress i was baking in the bag and started removing layers and eventually unzipped the bag to cool off.

Anyone else experience something similar, and why would this happen?

[coolkayaker1]

Hulk—I cannot explain your experience. Did you down a pint of Scotch in between inflating and deflating that Thermarest? :-)

I appreciate your post, because I have almost the same setup as you do: BA Lost Ranger 15, Thermarest Self Inflating Pro-pad. I just don’t have the HH Supershelter. I’ll have to see what my experience is when outside this autumn. I have read reviews of the BA Lost Ranger—if you look at REI or Altrec.com, you’ll see them, of people complaining specifically that is does not go anywhere near 15 degrees. Many say 40-45 degrees, and they re shivering their buttocks off. One can only guess that they may or may not be using the bag properly, or with the intended inner inflatable (which you and I, frankly, are not using either). So, hard to know, but your experience with the BALR seems to mimick theirs in some ways.

For what it’s worth, I refused to spend $79 on the BA inflatable sleeping mattress, but I did pull the plug and get one two days ago. Why? It’s ½ price in the REI Outlet store now. Google it and check it out, Hulkster. I cannot tell you if it’s any good or not as I don’t have it yet.

What I did buy, and I think it’s a complete waste of money, is the BA inflatable pillow ($20) for our bags, intended for the pouch at the head. Very uncomfortable, even when trying at different inflations. I’ll keep it as a sit pad on campouts, but honestly better for a pillow is just wadding up some clothes and sticking it in there.

Thanks for posting, Hulk.