How to convert R value to comfortable Temp rating.

[SSGHawk]

Thanks to a member we have an excellent of how to convert loft into temperature rating. In Order to figure out the weight to temperature performance it could be helpful to have a similar chart relating to R values. Does anyone how where one can be found?
I am planning a week of -40 degree F hammocking next winter in Canada and I am trying to determine the minimum amount of pad R value I will have to have if I am forced to the ground . I also would like to know the weight efficiency of pad R value versus down loft of various down fill powers.
All thought appreciated.
Regards,
Hawk AKA Sarge or Paul

[Insaniac99]

oof, I would not want to sleep that cold, No thank you. however I found this post which may help you: http://www.backpackinglight.com/cgi-...hread_id=10134

[RollinJoe]

Wow! From Texas to -40 Canada, you must be looking at the arctic ocean coast. Are you going to be skiing, snowshoeing or snowmobiling?

[SSGHawk]

PoeDog
Go Big or go home. Right?

Insaniac
That was exactly what I needed.
If 1.8" of Down ='s 6.9 R value, Down weight to R value just kills the pad weight to R Value Competition.

RollinJoe

Just planning 4-7 days having a great time playing with and rebuilding Coleman lanterns and stoves with a very good friend.
Sleeping out in -40 below (assuming the weather cooperates) is just a personal challenge. The Mountain is there so I just have to try climbing it.
BUT.......... like I said, I can bail and go to ground in the unheated garage or (THE SHAME) head for the spare bedroom in the house.

Regards to all.

Pop sickle Paul,

[Insaniac99]

Good luck, stay safe, stay warm, and write a good trip report when you get back :-)

[SSGHawk]

Roger that.

[RollinJoe]

.......... like I said, I can bail and go to ground in the unheated garage or (THE SHAME) head for the spare bedroom in the house.

Pop sickle Paul,

No shame in going indoors if you can't stay warm. The number one killer in the great outdoors is not being able to maintain core temperature and the number two (in my opinion) is male ego. I almost died once myself from the first and I've lost count on how many times from the second

[BillyBob58]

PoeDog
Go Big or go home. Right?

Insaniac
That was exactly what I needed.
If 1.8" of Down ='s 6.9 R value, Down weight to R value just kills the pad weight to R Value Competition.

RollinJoe

Just planning 4-7 days having a great time playing with and rebuilding Coleman lanterns and stoves with a very good friend.
Sleeping out in -40 below (assuming the weather cooperates) is just a personal challenge. The Mountain is there so I just have to try climbing it.
BUT.......... like I said, I can bail and go to ground in the unheated garage or (THE SHAME) head for the spare bedroom in the house.

Regards to all.

Pop sickle Paul,

I still need to look at that link some more, but that is sounding a bit off to me.

I have a table originally supplied by Youngblood when he was making the SPE for Speer hammocks, entitled "Some Observed Temperature Ratings for Combined Inflatable Pads and Closed Cell Foam Pads as Used in a Speer SPE". I tried to copy it here but it is not showing up correct. But, for example, it shows that a Thermarest Standard had an R value of 5.8 which has been used with OK results down to 12F. Another example is 1" of CCF with an R value of 4.3 OK down to 17F. And any of the results in those tables seem in the ball park to me from my experience and many others here have posted somewhat similar results. For example I have used a torso length TR ultralight with an R of 2.6 stacked in an SPE on top of a full length TR Ridgerest CCF which had a similar R value, total of 5 something R or close, and was very toasty at 18F, def could have gone lower.

Now, if 1.8" of down has an R value of 6.9, then it should be warm to zero or or maybe even well below. Obviously that is not happening for most folks. Just guessing here, there are a lot of variables, but I would expect a 1.8" thick UQ or TQ, IF everything is working perfectly, to be warm somewhere in the mid to high 30s at the best, for the average Joe. That is probably equal to an R value more like 3.5 or so, roughly.

Another example: some folks here have reported taking a 14 oz, 1/2" thick ( r value 2-2.5 ? anyone know? ) full length WM blue pad down into the 20s and lots have been at least OK in the low 30s, if memory serves. I doubt a 14 oz full length UQ would be quite that warm, and certainly not warmer.

IOW, I'm not at all sure that down kills the pad in the R value/weight competition. Maybe the CCF even wins at the less severe temps, although also depending on the fill power of the down. There are lots of reasons to choose a down UQ over a pad, but I don't think warmth to weight is one of them, and that is even before considering things like moisture or the need to go to ground should that arise. Although, the colder you get, like you are thinking of, the more the advantage might shift to high fill power down.

Ducttape has been to minus 22F with CCF pads. I wonder what the weight of those pads were?

EDIT: reading further in that link, I see this:
"However, this does not agree with what people need in practice. Big Agnes (which makes top bags and pads) lists R-6.5 pads as good for -25 degrees." So, that is another reason why I do not think 1.8" of down( good maybe to 35-40F) has an R value of 6.9. Probably more like about 2 or a bit more.

[Dirtnapper]

Where are you planning to go SSGHawk? I figure BC maybe east? You might want to look up the local forums here for in put from the locals that do winter hangs.

[SSGHawk]

Sorry for the delay. I think my buddy is about 1 hour North of New England, USA in Canada.

It is a GREAT idea to do some look ups on the locals here. He and I have been Coleman lantern buddies for years and have never met face to face but we have a lot of shared back grounds.He also always magically finds the exact very very old Coleman lanterns that I need for my collection. I will check the address and get back here.

As an experienced very cold weather ground camper and a newbie hanger, I will be taking both a a 50 below zero windchill ground set up and hanging set up.(Not including my clothing that will probably be at least good for minus 20 windchill.) And there will be a couple nice Coleman lanterns and heaters in the Garage with ample preplanned ventilation, if necessary.

I am VERY HARDCORE (that is at least half the fun ) but not stupid. I probably will have a walkie talkie in a special chest pocket (I NEVER sleep on my stomach)and check in with my buddy during the night. I also will be working with my friend Dan "ZELPH" the stove genius to have the right stove to heat up the snow to boiling water for the Hot Water bottles outside even in 30 MPH wind. I might even build a snow cave to state-of-the art specs and sleep there at least a night or all nights if the trees are too full of ice to be safe. Living on the edge, but using my head and the collective knowledge of the experts here to do so, is all part of the test.

THanks folks.
Paul