by Ryan Jordan | 2002-07-04 03:00:00-06
Sleeping-bag temperature ratings as reported by a manufacturer should mean absolutely nothing to you.
Certainly such ratings have been the focus of controversy in the outdoor-products industry for many years. Some manufacturers (such as Western Mountaineering) have garnered a reputation for being quite conservative with their ratings while others are the object of outright ridicule among outdoor enthusiasts.
The reasons for such discrepancies? First, we are all physiologically different and the level of insulation required for comfort at 20 deg F for one person may be dramatically different from the level of insulation required for another.
Second, there are no industry standards for measuring sleeping comfort levels. One promising development, however, is the use of a copper, heat-controlled, sweating mannequin that mimics the rate of heat output required to maintain a certain temperature while in a sleeping bag. Such a tool, and a standard method that employs it, will be valuable for evaluating sleeping bags from different manufacturers. It may even prove to be valuable for evaluating comparative performance of bivy sacks, tents, sleeping pads, and clothing. Protocols are evolving for applying the technology to these other types of gear. However, these methods are controversial (as they always are when they are subject to input from competing manufacturers) and they are expensive to implement for small- and medium-sized companies without adequate research and development budgets.
So does that mean you should blame the company for false advertising if their claimed bag rating doesn’t meet your expectations? No! You need to take responsibility for your own choices and not rely on obscure claims such as temperature ratings that are impossible to validate, and you should take a hard look at sleeping bag design.
Save yourself time muddling through manufacturer specifications and sales pitches and recognize that there are only three things to consider when assessing the warmth of a sleeping bag:
And a few things to consider for sleeping warm:
The bottom line: use your head and learn about the design factors that contribute to a warm sleeping bag. Also, test and validate manufacturer claims in your own backyard or on short overnight trips before committing to a longer trip where nights are expected to be near the sleeping bag’s temperature rating. Above all, develop your own equipment and style for sleeping warm.
Or just forget about all of this, trust the manufacturer’s ratings, and sleep warm by faith!
"Sleeping by Faith: Bag Temperature Ratings," by Ryan Jordan. BackpackingLight.com (ISSN 1537-0364).
http://backpackinglight.com/cgi-bin/backpackinglight/00024.html, 2002-07-04 03:00:00-06.