sleeping bags

[saltysenior]

How accurate are the temperature ratings on sleeping bags?  My new bag just purchased is rated @ 20 degrees.  Can I rely on that statement when I use it?

[perterra]

Everybody sleeps different, some hot some cold so it's a general guess at best but they are usually close enough that you will survive.

I would road test it in the back yard before heading straight to the cold weather with it. If it's a high end bag chances are it will do what it says it will, as you get into cheaper bags the ratings can get iffy. I have had cheap bags that were fantastic and mid priced bags that were just okay. Until it shrunk in the wash (my story and I'm sticking to it) I used a Coleman exponent mummy bag rated for 20§. It worked fine down to the mid 20's when I was thinner, uh when the bag was bigger.

Currently I use a cheap ($40 close out) Columbia Elk ridge mummy bag thats rated 0§ and it will probably get down that low and still work if you sleep in warm ups or fleece but 0 might be a bit of a stretch. My wife uses a Kelty Corona semi mummy bag rated to 20§ that shes had for several years, it's as warm as my 0 bag.

If it's truly cold wear a watch cap to bed and it will add degrees to the bag, also I have found a high calorie snack before bed keeps the furnace burning a little longer on those nights where the water in the coffe pot freezes solid.

[wavery]

If it's truly cold wear a watch cap to bed and it will add degrees to the bag, also I have found a high calorie snack before bed keeps the furnace burning a little longer on those nights where the water in the coffe pot freezes solid.

Don't ignore the "Watch Cap" suggestion.

Any scuba diver or mountain climber will tell you that you loose 50% of your body heat through the top of your head. A good wool hat will go a long ways toward keeping in your body heat.

[perterra]

Don't ignore the "Watch Cap" suggestion.

Any scuba diver or mountain climber will tell you that you loose 50% of your body heat through the top of your head. A good wool hat will go a long ways toward keeping in your body heat.

My wife has told me it probably doesnt work as well for me given the teaspoon full of blood that circulates in my head. I still do it just to spite her.

[tplife]

Don't ignore the "Watch Cap" suggestion.

Any scuba diver or mountain climber will tell you that you loose 50% of your body heat through the top of your head. A good wool hat will go a long ways toward keeping in your body heat.

Actually no.  You can lose up to 55% of your body heat through your head when engaged in strenuous activity (like diving or mountain climbinb, chopping wood, etc.).  When  asleep or motionless you can lose as little as 7% of your body heat through the top of your head.  It all depends on cardiac output that radiates heat more quickly when more blood circulates due to activity.  Using a pillow alone will reduce about half of that heat loss, and a quality down bag with a draft tube and offset channels of down will keep you dreaming 'till dawn...

['tiredTeacher]

How accurate are the temperature ratings on sleeping bags?  My new bag just purchased is rated @ 20 degrees.  Can I rely on that statement when I use it?

Sure, but why wouldn't you tote along a fleece liner, too? You ain't backpacking.
I've found them to be accurate enough inside an enclosure.  It's when a breeze blows, even gently, across the bag that you'll be in a world of hurt.

[LACamper]

I've come to the conclusion that the temp posted on sleeping bag is the survival rating. You won't end up hypothermic at that temp in that sleeping bag! That doesn't mean you will be comfortable either.
Keep in mind that your body compresses the insulation under you making it inefficient. In a tent that puts you in contact with the ground. In a popup I guess it depends on how insulated your bunk ends are... A good mattress goes a long way!

[saltysenior]

you are right about the bunk ends....what would be the best insulation to put between the bunk ends and the cushion you sleep on ??

[perterra]

We just use a memory foam pad and it's never been cool underneath. Camped down in to the teens dry camping and cold wasnt an issue thru the bunk end.

[CajunCamper]

I've come to the conclusion that the temp posted on sleeping bag is the survival rating. You won't end up hypothermic at that temp in that sleeping bag! That doesn't mean you will be comfortable either.
Keep in mind that your body compresses the insulation under you making it inefficient. In a tent that puts you in contact with the ground. In a popup I guess it depends on how insulated your bunk ends are... A good mattress goes a long way!

Your exactly right LACamper, the rating is a survival rating not a comfort level. Many people have purchased the wrong bags by not understanding the rating.

[CajunCamper]

You may find this article helpful:

Sleeping Bag Temperature Ratings
Sorting through the confusion.

Not too long ago, while in Alaska on assignment, I had occasion to spend a night or two testing a synthetic sleeping bag rated to 20 degrees. Granted it was raining, although the bag stayed relatively dry. Sure, I was tired from a 16-hour trek in chilly conditions. But feeling chilled at 35 degrees while inside the bag, even wearing dry Thermax underwear, dry wool socks, and a Polartec hat was not my idea of accurate temperature rating--this from a person who can regularly slumber comfortably at 10 degrees in a 20 degree rated down bag. What's up with temperature ratings?

According to Fred Williams, founder and past president of Moonstone, temperature ratings as they are currently used are pure bunk and should be abandoned.

"It is not all that uncommon to have users judge the minimum comfort limit of an identical sleeping bag up to 20 degrees apart. I know of at least one case where two users judged the same sleeping bag more than 30 degrees apart!" says Williams. "Even without the variables of environmental factors, clothing worn, food eaten, pads used, body size, fitness, etc., the perception of 'comfort' varies wildly."

"Testing instruments such as the copper mannequin provide clo data using a very controlled environment. The mannequin is a fixed size and does not roll. The comparative data that's collected is great for evaluating the comparative insulating power of bags used by the mannequin," adds Williams, "but how does it address the variables of body size (a small body in a large bag) or movement (nighttime rollers who constantly crush insulation), metabolism, and the other factors of the field?"

Gary Schaezlein, owner of Western Mountain Sports, manufacturers of Western Mountaineering down sleeping bags agrees with Williams wholeheartedly.

"We just try to be honest with what we are putting out and provide for our customer in the worst of scenarios, not the most optimistic," says Schaezlein. "In fact several years ago, we were copper mannequin tested and found our ratings were 20 degrees too warm--our 20 degree bag tested to 0 degrees for example. The bottom line with a bag is it must keep you warm."

Hallelujah to that! Moonstone also reports that they overfill their bags to ensure warmth. Wise field advise that I have heard dispensed over the years is that you can always unzip a bag if you are too warm, but you're going to have a problem trying to add more down or insulation if the bag's too cold. Of course, this doesn't mean you want to buy a bag that you will be sweltering in 90% of the time either.

One company, when asked how they were rating their bags, went so far as to state that they had their bags tested by the copper mannequin a number of years ago, and simply extrapolated the information into their current line.

Of course, those companies who choose to be more optimistic with their temperature ratings often come out ahead when you only catalogue-compare price, stuff size, temperature rating and weight. As any knowledgable retailer will tell you, as long as you know how to compare bags properly, temperature ratings are of little significance and merely serve as a starting point or a place of reference for the eventual purchase--hopefully an educated one.

The first word of caution from Williams is "don't get too caught up in the loft game because some insulations pack more insulating punch per unit thickness than others."

Indeed, tests conducted at Kansas State University indicated that a LiteLoft bag (no manufacturer listed) which had been abused until it had lost 27% of its original loft still managed to maintain 94% of its original insulating ability.

Because of all the confusion, a number of heavy hitters in the industry, including Cascade Designs, Sierra Designs, REI, Marmot and 3M insulations, have banded together to attempt to hammer out an unbiased, meaningful, understandable and standardized rating system. Don't expect anything to happen in the next year however, since not everyone in the industry agrees that standardized temperature ratings is a good or even achievable idea.

What, then, are the most important criteria to consider when buying a bag? Look at the foot section, hood area and draft tube. How are they designed? Are there any obvious cold spots? How do they compare with the other bag(s)? How much insulation is in the bag? Consider that bigger bags require more insulation to provide equal insulating qualities as smaller or more narrow cut bags. On down bags, do the compartments feel firm ( a good sign that prevents cold spots forming since down shift is minimized) or soft and fluid (a poor sign since the down is free to 'fluidly' move around the tube creating cold spots--only exception are those bags intended for the user to be able to shift down from top to bottom to adjust for temperature fluctuations).

Contributed By: Michael Hodgson

Michael Hodgson is a an award-winning journalist and author of numerous books including Camping for Dummies, Compass and Map Navigator, and Facing the Extreme. He is a volunteer instructor for the American Red Cross, Nevada County Sheriff's Search & Rescue team and was a former mountain guide. Michael is well-known for his sense of humor and eagerness to try anything once in the pursuit of a really good story. His friends remain amazed that he can still walk. He has partnered with his journalist-wife, Therese Iknoian, on four web sites: his own //www.AdventureNetwork.com, plus //www.GearTrends.com, //www.TotalFitnessNetwork.com, and //www.SNEWSnet.com

[tplife]

I've come to the conclusion that the temp posted on sleeping bag is the survival rating. You won't end up hypothermic at that temp in that sleeping bag! That doesn't mean you will be comfortable either.
Keep in mind that your body compresses the insulation under you making it inefficient. In a tent that puts you in contact with the ground. In a popup I guess it depends on how insulated your bunk ends are... A good mattress goes a long way!

We'll agree to disagree on this one, I've always found the ratings to be accurate for comfort.  Those ratings are understood to be in a wind-proof enclosure at average humidity sleeping on an open-cell foam pad for ground insulation.  Once wind and moisture are added to the ratings, everything changes.  Since it's the air trapped around your body by the insulation that keeps you warm, the insulation under you is not a cooling factor unless you are sleeping on a hollow-chambered pad, in which case you are a heat sink contributing warmth to the pad, which will cool until it's the same temp as the outside air, giving you hypothermia.  Most hypothermia occurs between 30 and 50-degrees F.  Always insisting on the very best quality for the money (value), we've not gone wrong buying from Marmot and A16.

[perterra]

We'll agree to disagree on this one, I've always found the ratings to be accurate for comfort.  .

I have found different brands to be different in the accuracy of their ratings.

[LACamper]

a section of reflectix or foam board on the bunk ends are a good idea also.