Articles (2020)

Wind Shirt Wars Review Summary

Wind Shirt Wars Review Summary

Introduction

A wind shirt is simply a single-layer woven (nylon or polyester) torso garment cut to the pattern of a shirt, pullover, or jacket. Key characteristics of a wind shirt are extremely light weight (typically not more than 8 oz in size medium), high breathability, and some water resistance (usually provided by a durable water repellent finish, or DWR).

A wind shirt is probably the most versatile piece of clothing you can carry in your pack. Typically worn over a base layer, they can also be worn on their own in warm weather. Wind shirts of course provide protection from the wind chill effect, as their name implies, but they can also be worn while hiking for light to moderate rain protection, for added warmth in cool weather (e.g., to slow the process of evaporative cooling that occurs rapidly at rest stops), and for sun and insect protection. For a more thorough treatment of the benefits of a wind shirt, refer to Part 2 of Jordan and Nelson’s Clothing and Sleep Systems for Mountain Hiking, also available from BackpackingLight.COM.

This review includes wind shirts from GoLite, Mardale, Montane, and Wild Things.

Review Criteria

All wind shirts present in this review have been tested in both laboratory-simulated and real-world field conditions (with the exception of the GoLite Bark, which was not submitted for this review in time for field-testing, and thus, will not be considered for a Trail’s Best Award until field testing is complete). Key feature categories investigated in the review included fabric specifications and performance, fit, and features. Each product review is summarized in the Review Summary Table (below), with subjective designations (excellent, very good, good, fair, or poor) assigned relative to each other (i.e., not on an absolute scale, or on a scale that can be compared with other products outside this review).

The Products

  • GoLite Bark (jacket)
  • Mardale Aerolite (pullover)
  • Montane Featherlite Smock (pullover)
  • Wild Things Wind Shirt (pullover)

Review Summary Tables

Click here for a 1-Page (Printable) Adobe PDF Version of the Summary Table, Opened in a New Window

Review Discussion

Fabric Specifications and Performance

GoLite. The Bark jacket is made with “Silmond,” a trademarked 1.9 oz/yd2 polyester that is comfortable when worn next-to-skin (we would have rated the Bark’s next to skin comfort as “excellent” if it wasn’t for the noticeable abrasion of the inner seams when worn without a shirt). Silmond is uncoated, so it breathes well and dries quickly, and the combination of its tight microfiber weave and heavier fabric weight (compared to the other wind shirts in this review) provide very good water and excellent wind resistance. We found the Silmond to be the most durable fabric of the lot, and would highly recommend it if your highest priority was bushwhacking through slide alder.

Mardale. The Mardale Aerolite’s 2.0 oz/yd2 Pertex RS5 is a ripstop nylon that did not perform to our expectations, considering the popularity of Pertex nylons. The fabric is heavily calendared (a process by which the fabric is heat-treated on one side to improve strength and decrease porosity) on the inside, which inhibited its breathability and next-to-skin comfort (the fabric tended to feel much “clammier” than the other products), although it made for excellent wind resistance and very good water resistance.

Montane. Montane’s Featherlite collection is made using Pertex Microlight, a 1.2 oz/yd2 ripstop nylon that is lightly calendared on its inner surface. Of the four products tested in this review, the Featherlite’s next-to-skin comfort, breathability, and drying time were tops. The Pertex Microlight feels like satin when worn next-to-skin and breathed well enough during light exercise that clamminess was never an issue. As expected, the thinner fabric of the Featherlite suffers in the area of wind and water resistance, but we were surprised by the quality of the fluorocarbon DWR finish on the Featherlite and its ability to shed light rain with ease. In addition, we wore the Featherlite through some pretty harsh brush conditions and noticed only very slight abrasion marks on the fabric. For a 1.2 oz/yd2 fabric weight, we were very impressed with its durability.

Wild Things. The Wild Things Wind Shirt uses the lightest fabric of the lot, an uncoated 1.1 oz/yd2 ripstop nylon. As expected, the paper-thin fabric did not withstand the rigors of busting brush while traveling cross-country through a dense forest. In addition, the lightweight nylon cannot be counted on for its ability to shed anything but the lightest mist or drizzle, and would not be appropriate as a wind shell while standing around camp in a cold breeze. However, such a light fabric has extreme advantages for the hiker that stays on the move: its breathability was unmatched, keeping us comfortable even while climbing steep hills with a pack in only moderately cool (40s) weather. But if you’re looking for a wind shirt that is appropriate for more stationary activities or harsher conditions, you may want to consider one of the other three products.

DWR Note: All wind shirts used fabric with a durable water repellent (DWR) finish.

Features and Fit

GoLite. The Bark was the only full-zipper jacket in this review, and one of only two with a hood. We found these two features to be well worth their added weight. The zipper provided an ability to ventilate that was not found in the other wind shirts, and allowed us to wear the jacket backwards with a pack on to keep airflow around your back (as recommended in Ray Jardine’s Beyond Backpacking), which was a very nice feature for hiking in high winds or rain. The hood extends the cold weather comfort range of this shell tremendously, because it allows you to wear a hat underneath it, and thus, preserve a great deal of body heat that would normally be lost through the collar. In addition, we thought that a hood might be a nice addition during mosquito season when layered with a noseeum mesh headnet. Our only gripes with the hood were that it did not have 1-handed pull drawstrings, and that it was sized a bit too small for adequate layering and head-turning comfort. The bark had nonadjustable elastic hems and cuffs (comfortably sized), but we would have preferred at least a drawcord-adjustable hem (and/or a 2-way zipper that could be zipped up from the bottom) that could have been used to control chimney venting through the garment. The Bark was the only pocket-rich jacket in our review, providing two convenient zippered “handwarmer” pockets and a single small zippered chest pocket appropriate for minor essentials (and stuffing the jacket). The Bark’s construction quality appears to be excellent, with reinforcement stitching in all the right places.

Mardale. The Aerolite pullover had a fairly deep neck zipper (deeper than the Montane Featherlite but not as deep as the Wild Things Wind Shirt), but was limited in length by the presence of a zippered map pocket (approximately 6″ tall and 11″ wide) that was made with nylon mesh and protected with a storm flap. The hood, like that of the GoLite Bark, could have a roomier cut (a minor issue) but its degree of articulation (i.e., head-turning comfort) was miserable, particularly for those of reviewers that wear glasses. In addition, the hood drawcords are poorly designed, and not only require two hands, but quite a lot of patience if you have cold hands. The Aerolite has a drawcord hem and a terrific hem cut that allows the jacket to cover your butt, a nice feature while hiking in the rain. Another saving grace on the Aerolite is the presence of a side zipper that travels from the hem to the armpit, providing a wonderful option for ventilation. Our only complaint is that the zipper is not available on both sides, so that a hip belt can be used without binding the entire hem of the jacket. Overall, we found the design and construction quality of the Mardale jacket to be fair–there were unbound seam edges in our product sample that frayed significantly, in addition to the need for reinforcement stitching in key wear areas (e.g., near the 1-handed pull loop on the hem drawcord).

Montane.  Montane’s Featherlite wind shirt provided the trimmest cut of the four products tested, so the buyer may want to consider sizing up one size if they desire some added room. On the other hand, the trim cut provides a very efficient garment for both heat and moisture transfer, allowing the product to perform to its potential in more demanding (colder) conditions. Other than the Lycra elastic cuffs and hem, the only distinguishing feature of the Featherlite is a short neck zipper and mock-T collar. Lack of features on this wind shirt means that there is no place to stow your keys, lighter, or push-button micro-light, but it also means an astonishing lack of weight–the Featherlite took the honors for light weight and weighed a scant 3.2 oz in size M, less than half as much as both the GoLite and Mardale shells, and full 25% lighter than its closest competitor, the Wild Things Wind shirt. The simplistic style, negligible weight, and incredible packability were deciding factors in our review team’s decision to include the Featherlite as part of their regular pack list. Construction quality of the Featherlite is excellent, on par with a small, high-quality custom shop.

Wild Things. The design of the Wild Things Wind Shirt is very similar to the pullover-style of the Montane Featherlite. The key features that distinguish the two include the cuff closure (Montane uses a Lycra cuff while Wild Things uses a less-functional hook-and-loop closure*), the hem (Montane uses a Lycra hem while Wild Things uses a non-elastic felled hem–in addition, the Wild Things’ hem was long enough to remain tucked in while reaching overhead–a very nice touch that made for slim layering), the neck zipper (deeper on the Wild Things, thus providing more ventilation), and the collar height (higher on the Wild Things, making it nicer to layer with a balaclava). Construction quality of the Wild Things Wind Shirt gets high marks overall, but we dinged them in this category because of the use of hook-and-loop with such a fragile fabric, and a questionable fabric specification (1.1 oz/yd2 nylon is not particularly durable for anything but trail walking–something our testers learned the hard way) for a garment that is likely to be worn more than any other piece in one’s clothing ensemble.

* We felt that the use of hook-and-loop closures on such a light fabric was inappropriate. Closing and opening the cuffs repeatedly on the Wild Things Wind Shirt eventually stressed the seams on the nylon until stitching began to tear away from the fabric.

Summary

GoLite Bark

For a full-featured jacket (hood, pockets, zippers), the GoLite Bark’s 8.0-oz weight provides a performance-to-weight bargain. Constructed with an attention to detail and quality, good fit, and a very comfortable fabric, the Bark won the hearts of our testers and is one of their favorite jackets. Only time will tell, however, whether or not the 8.0-oz weight will displace an ultralight wind shirt (like the Montane and Wild Things products reviewed herein) when it’s time to pack up and pay the piper. [Editor’s Note: We did not receive the GoLite Bark in time to include a comprehensive, long-term field review. Therefore, interpretations of the Bark’s performance in comparison to other products in this review should be taken conditionally. Backpacking Light will be testing and reviewing the Bark extensively in the coming months, after which time, a comprehensive field performance review will be released.]

Contact: GoLite http://www.golite.com/

Mardale Aerolite

The Mardale Aerolite’s novel (single side-zippered) anorak design was not enough to earn an overall vote of confidence among our testers. Our recommendations to the manufacturer include: add a second side zipper; increase quality of construction; change the hood design or lose it entirely; and change the fabric specification to something that is more comfortable when worn with a short-sleeve t-shirt.

Contact: Mardale Clothing, Ltd. http://www.mardale.com/

Backpacking Light
Trail’s Best Award 2001

Montane Featherlite Smock

Montane Featherlite

This was a clear favorite among our reviewers. Extreme light weight and packability means that the Featherlite will seldom (if ever) be left behind. Its simplicity of style was a refreshing option in a market flooded with “feature-rich” alternatives. Although our initial performance expectations of the Featherlite’s Pertex Microlight were not optimistic, once we took the Featherlite to the field and put it through the ringer of heat, insects, rain, wind, and sun, we were beyond impressed and amazed that a 1.2 oz/yd2 fabric can perform to such specifications. One of the finest pieces of lightweight clothing we’ve seen, the Featherlite earns a well-deserved Backpacking Light Trail’s Best Award. Our only recommendations: (1) the neck zipper could be lengthened to improve ventilation, and (2) improve U.S. distribution channels.

Contact: Montane (Chonos, Ltd.) http://www.montane.co.uk

Wild Things 1.1 oz Nylon Wind shirt

Wild Things almost hit the target with this well-designed wind shirt, predominatly due to the long hem, high collar, and deep neck zipper. But the inappropriate fabric specification (not particularly noticeable when reviewed independently, but a stark contrast to the luxurious Pertex Microlight of the Montane Featherlite) for situations requiring at least a reasonable degree of water resistance and durability make this garment suitable for only specialized situtations, thus limiting the versatility that should be the hallmark feature of a wind shirt. Needless to say, Wild Things makes a solid product that is well worth its bargain-basement price tag and ultralight weight.

Contact: Wild Things Gear http://www.wildthingsgear.com/

Hike ‘N Light Alcohol Stove

Hike ‘N Light Alcohol Stove

Introduction

Jack McGuire of Hike N’ Light, Inc., has created an alcohol stove with a 4-inch diameter burner that may very well be the ticket for heating large volumes of water in big pots, something most alcohol stoves aren’t particularly adept at.

A cottage industry manufacturer from Mountainside, N.J., Hike N’ Light offers an alcohol-based burner that is unique on the market for its substantial burner size that is easily larger than most homemade and commercially available alcohol stoves. Consequently, the Hike N’ Light stove may be one of the few alcohol stove designs particularly suitable for those wanting to cook for larger groups or with larger pots.

The Facts

The burner weighs 2.0 oz and is accompanied by three clips that secure to the burner and weigh 0.7 oz (total), plus a preheat pad that weighs 1.4 oz (verified on our scales). Thus, as shipped, the stove weighs a total of 4.1 oz (manufacturer’s claim is 4.0 oz) but does not include a windscreen (the manufacturer recommends doubled-over aluminum foil with an air intake vent cut into the bottom).

The manufacturer recommends using approximately two tablespoons of alcohol (i.e., 30 ml, or about 1 oz) to preheat the stove, with 1-3 oz of alcohol in the burner (which has a 3-oz capacity. Reported burn times by the manufacturer are: 6.25, 15+, and 45 minutes for 1, 2, or 3 oz of burner fuel, respectively.

Preliminary Performance Review

We’ve had the chance to run several tests with the Hike ‘N Light Alcohol Stove. The most important lesson we learned is that for most mild conditions, the amount of preheat fuel recommended by the manufacturer was excessive, causing the burner to overheat and burn its fuel faster than necessary, and causing a large flame pattern that not only engulfed the cookpot (Figure 1), but also made it dangerous and risky to access the cookpot’s lid, or to cook under the protection of an awning of a tent or tarp. Once the preheat fuel was consumed, however, the flame was tempered to a more manageable fire (Figure 2) with a nice-looking burn pattern.

FIGURE 1

FIGURE 2

Conclusion

Our first impression of the Hike N’ Light stove was that of excessive weight and fuel consumption when compared to smaller stoves available on the market or made by using “homemade” instructions (i.e., pop can stoves). However, as we play with it a bit more, it is clear that the Hike N’ Light’s flame pattern may have potential to allow alcohol stove cooking to be accomplished for higher water volumes (e.g., groups, boiling snow, large pots). For more performance-based information about the Hike N’ Light Stove, you may want to consult the more comprehensive reviews performed by the BackpackGearTest organization.

Contact Information

Hike N’ Light, Inc.
P.O. Box 1423
Mountainside, N.J. 07092
Phone: 908-232-4349

Email: info@HikeNLight.com
Internet: http://www.hikenlight.com/

Nutritional Considerations for Cold Weather Hiking

Nutritional Considerations for Cold Weather Hiking

Introduction

As I stood in the frigid cold stomping my feet in the snow, watching my husband hastily putting up the tent in the fading light, I admitted defeat. Three separate attempts on Mt. Whiteface (a relatively insignificant 4,000-footer in the White Mountains) and three times defeated by weather. Leaving home, we had optimistically calculated a same-day return. Before we had traveled a mile up the trail, however, we realized that it was a good thing we had packed food and gear for two days. Snow that had just been dusting the lowlands quickly turned to snowdrifts as we ascended. We were soon post-holing up to our knees, castigating ourselves for leaving our snowshoes in the warmth of our basement one hundred miles away. Following in the footsteps of my husband, I had it fairly easy, but by 4 pm I was exhausted and grateful to see the sun setting, knowing that fading light would be the catalyst for setting up camp for the night. Our destination nowhere in sight, we had to rethink the itinerary.

The tent ready, my husband turned eagerly and asked where I wanted to set up the kitchen. I snapped back: “No Food! I’m too cold. I can’t eat.” as I dove into the tent and the insulating layers of sleeping bag and liner. Concerned for my well-being (and perhaps a bit hungry himself), he soon had the stove humming and fixed dinner as I dozed off. “Here, drink this, you’re dehydrated,” he admonished as he handed hot soup into the tent. It hurts to say it, but he was absolutely right. I hadn’t reckoned how quickly the extreme hiking effort (ascending and post-holing) and the dry cold air would sap the moisture from my pores and from my breath. I had not replenished my losses, repeatedly rejecting his offers of a sip from his water bottle. The dehydration had turned to nausea at the thought of dinner. It was not the cold that was defeating me-it was my own stupidity. What had I learned from this day’s journey?

Snack Often!

First, recognize that when hiking in extreme cold (below 10*F), you will be burning an additional 250-500 Calories/day (see Endnote 1). Your body will be running the furnace at full blast to keep your core temperature within reasonable limits, but the layers you are wearing should protect you from using excessive Calories to keep warm. The real Calorie burner is the extra effort it takes to move more gear over worse terrain. Even relatively level terrain is more challenging if you are post-holing into knee-deep snow at every step. It takes twice as many Calories to walk in soft packed snow as it does to walk the same distance on cleared trails (Askew et al., 1989).

Getting more fuel when weather is extremely cold becomes a challenge, since slowing down for a three course lunch means a drop in body temperature with resulting cold fingers and toes. Thus, “grazing” should be the meal pattern: small, frequent snacks throughout the day to most effectively fuel your muscles. To adapt your normal warm weather menu, plan to add 4-8 extra servings of high carbohydrate/high fat snacks per day, with lunch reduced to the status of a “large snack”. Plan to nibble along the trail, as hands and feet will freeze up quickly if you stop for a mac ‘n cheese delay.

Put on extra layers before you need them, as soon as you slow down, to avoid long moments of uncomfortably cold extremities later on. To avoid robbing your arms and legs of necessary circulation, eat small meals, rather than large meals that shunt blood to the intestine. Timing your meals will also make a difference in how you feel. Eating dinner or a hearty snack just before you go to sleep (500-1200 Calories) will help you sleep warmer and more soundly.

Editor’s Comment: One of our reviewers adds, and Dr. Braaten agrees, that “…these calories should include a high proportion of fats, which can be utilized more efficiently, and a significant portion of protein, needed to restore muscular endurance for the following days’ activities, should be included in that amount.”

Sip Often!

Stay Hydrated. Dehydration compounds the effects of cold weather exertion, causing more physical strain on heart and skeletal muscles, leading to earlier exhaustion. Avoid dehydration by sipping water often throughout the day. To keep water bottles from freezing, pack them inside your jacket next to your body, sleep with them in your sleeping bag (along with your boots–in a plastic bag of course), and buy/make an insulated bottle jacket. Two partially full bottles will freeze faster than one full bottle, so combine the water bottles if you have two that are less than half full. Adding gatorade/Kool-Aid will depress the freezing point, keeping it liquid longer, but at less than 10*F even sugar water will freeze. Fluids that contain too much sugar will promote diuresis (you lose more water than you gain), so a 7% solution, or approximately 1/3 C powder per liter, is recommended to maintain optimum hydration status (Rintamaki et al., 1995).

Foods to Avoid

Avoid any food that makes you “think you’re hot when you’re not”. Foods that cause you to break out in a sweat–alcohol or spicy foods containing hot peppers, for example. Even too much hot fluid at once can cause vasodilation, allowing precious warmth to escape from your pores. Water/fluid should be about body temperature, or taken in small sips if very hot (Rintamaki et al., 1995). Avoid high protein snacks, as they increase your water requirement and reduce your cold tolerance. Ten to 15% Calories from protein is generally adequate (Stroud et al., 1996).

Prepare in Advance

Be mindful of the effect subzero temperature will have on your food rations. What are you going to do with 5 bagels that have frozen solid on your high country/mid-winter trip? Use them for hockey pucks? Take chips or cheese crackers instead. Generally, the less water in any food, the better. The lower water content makes them less likely to freeze solid. Pack dehydrated soup and instant cereal mixes, Summit bars or granola bars–foods that require little or no preparation and that contain no water. (See www.frc.mass.edu/bbraate/packlite/index.htm for Water Content of Common Trail Foods; Ed. Note 9/12/04: Dead link) Do as much of the food preparation as possible in the warmth of your kitchen: slice sausage/Kielbasa and cheese, package food in baggies so that all you have to do is heat water to a boil and dump the contents in. No stirring required; no frozen fingers. I even remove tea bags from their wrapper. Think through every step of food preparation that will be required on the trail as though you had to do it with mittens on, and simplify accordingly.

Take Extra Fuel

Beside needing more fuel yourself, you’ll need at least 3 times more stove fuel to melt snow and heat it to boiling (not correcting for additional environmental losses due to conductance, exposure to wind, etc.). Everything will take longer–take plenty of fuel (see Endnote 2).

When melting snow, be aware that you should start with some liquid water in your kettle, otherwise your pan will scorch and the water will taste burned. (Editor’s Note: some water in the kettle will also improve the heat transfer efficiency among the water phases in the pot and promote faster melting time).

Because there were teenagers awaiting our attention at home, we returned to the valley the next morning. We had not conquered Mt. Whiteface this trip, but it was not the cold that defeated us. Rather, because the cold had discouraged the masses, we had been graciously provided with what we needed most: profound solitude, spirit-renewing perspective. Undaunted, we could eagerly anticipate “the next time”, better educated than when we began this trip. Next time, I’ll bring the snowshoes, and yes, I’ll drink my water throughout the day.

Key Points to Remember

 

  • Sip water/fluids throughout the day.
  • Take at least three times more fuel than you would for summer hiking.
  • Avoid a high protein diet. Eat frequent high carbohydrate/high fat snacks.
  • Have a substantial snack just before bedtime (high protein OK here).
  • Pack no-fuss meals: instant hot soups or cereals, hot drinks.
  • Do the prep work at home: wash veggies/fruit, slice cheese/sausage in the warmth of your kitchen.
  • Pack dehydrated/low moisture foods.

 

End Notes

1. Editor’s Comment: One of our reviewers wrote: “Dr. Braaten claims that you will burn an additional 250-500 calories per day at cold temps. This seems low, indicating an amount of increase due to the basal metabolism (thermoregulation) functions alone, and may not consider the additional extreme physical exertion normally encountered under winter conditions.” We gave Dr. Braaten the opportunity to respond, and she replied: “Most folks will dress adequately for cold conditions, so increased BMR is unlikely/insignificant. I agree, cutting new trail through three foot snow drifts would increase caloric needs substantially…However, I suspect that most of us will be following a blazed trail, or only occasionally putting out that kind of effort. Add to that shorter days (less daylight), and calories may come out about the same as they would under “friendlier” conditions.”

2. We’re obsessive about mimimal fuel on longer treks in moderate weather, (see our website) but quite liberal when camped in subzero temperatures. Aside from more fuel required to heat water for cooking, we drink more hot fluids, and melt snow. Better to err on the side of safety. – BB

Bibliography

Askew, Eldon W. Nutrition for a cold environment. Phys and Sportsmed. 1989, 17(12).

Rintamaki, H., T. Makinen, J. Oksa and J Latvala. Water balance and physical performance in cold. Arctic Med Res 1995, 54 Suppl 2:32-6.

Stroud,MA, AA Jackson and JC Waterlow. Protein turnover rates of two human subjects during an unassisted crossing of Antarctica. Br J Nutr. 1996, 76(2):165-74.

RBH Designs Vapor Barrier Hand & Footwear

RBH Designs Vapor Barrier Hand & Footwear

Introduction

A small company from Connecticut is producing innovative cold weather products in a big way. All products are based on vapor barrier (VB) technology, in which a vapor-impermeable (and waterproof) membrane is placed between the surface of the skin and the clothing’s insulation. RBH Designs’ inaugural product line focuses on insulated VB handwear and footwear.

Product Line

We received a handful of samples from RBH, including heavily insulated (Polarguard 3D) expedition mountaineering mitts with a VB lining, fleece-insulated “trigger mitts” (i.e., like mittens but with a detached index finger) with a VB lining, VB-lined fleece socks, and VB sock liners.

Preliminary Testing

We had the privilege of testing RBH’s flagship product, the Polarguard 3D-insulated Vapor Mitts (Figure 1). During an Arctic cold front that passed through Montana this winter, we were pleased to test the mitts during a front-porch bivouac at 27 °F — below zero. I donned an expedition down jacket, slid into a winter-strength down sleeping bag, and cinched it up around my armpits so that my hands and arms would remain free. I slept on a closed cell foam pad and sealed myself up in a Pertex Endurance bivy sack. Thus, the only insulation between the skin of my fingers and hands and the brisk outside air was that provided by the Vapor Mitts. I lasted about six hours in the cold before the ice on my face mask began to interfere with my breathing, so I called it a night. However, the Vapor Mitts kept my fingers comfortable and they never went numb or even felt cold.

Figure 1. Vapor Mitts

In contrast, I completed the same test in similar temperatures on the following night using the industry gold standard expedition mitt–the Outdoor Research Pro Modular Mitt with its double pile liners. I lasted about two hours before my fingers became numb, so this comparison was hardly a contest. However, instead of calling it quits, I warmed up my fingers and returned outside with RBH’s Vapor Triggs (Figure 2) with their Vapr-Thrm fleece liners. These gloves, although not as warm as the Polarguard-insulated model, were able to get me by for four more hours before I had to withdraw my hands into my sleeping bag, as my index fingers were beginning to get cold. Thus, it appears that both RBH’s Polarguard 3D and fleece Vapr-Thrm liners provide serious protection from the cold. Because the Vapor Triggs were a bit thinner than the Polarguard-insulated mitts, they are more appropriate for activities requiring more hand mobility, like skiing or climbing. In fact, the mitts are so bulky, that they serve little purpose other than as emergency bivouac gear, unless one enjoys the feeling of slogging up the side of a very, very tall mountain on a very, very cold day with a piolet in hand.

Figure 2. Fleece Vapr-Thrm insulated Trigger Mitts (“Vapor Triggs”) and liner

While our biggest compliment for the Vapor Mitts and Triggs is the warmth and weight of the liners (e.g., 6 oz for the Polarguard 3D mitt liner pair), our biggest complaint is the weight of the shells (e.g., 6.5 oz for the mitt shell). Granted, this handwear is designed for expedition use, but for the weekend warrior interested in keeping his digits and not necessarily needing supreme durability, a much lighter shell could be offered. In addition, not everyone needs a mitt that requires so much insulation, and thinner versions of Polarguard-insulated mitts (or for that matter, down-insulated mitts!) with ultralight shells would be a fantastic alternative for the lightweight winter traveler. The bottom line is this: RBH has developed a VB technology that seems to be very functional, and in stark contrast to VB technologies of the past–very comfortable. The possibilities for market development are endless. 

We used RBH’s fleece Vapr-Thrm socks (advertised as a “boot liner,” 5.0 oz men’s size 9, Figure 3) all winter long while climbing, snowshoeing, and skiing in temperatures down to -15 °F. They outperformed any combination of fleece or pile sock technology we’ve ever tried, and not once did our feet get dangerously cold, despite the fact that nearly all of our activity was performed in single leather mountaineering boots that were only lightly insulated (Scarpa Freneys).

Figure 3. Fleece Vapr-Thrm Socks

The only thing we missed with the RBH fleece socks vs. other wool and fleece socks we use is the lack of stretch in the fleece material. As such, it becomes very important to “nail the fit,” so to speak, as the seams in the socks are substantial enough to cause problems and binding if the fit is incorrect. Our socks fit perfectly, and we hardly noticed the seams.

We’ve also been experimenting with RBH’s VB sock liners (1.2 oz men’s size 9, Figure 4) which are manufactured from a 4-way stretch vapor barrier that has a wicking lining. We found these to be ideal when worn in combination with the RBH fleece Vapr-Thrm socks, as they assisted in both moisture dispersal and comfort. In addition, we wore the sock liners in milder conditions (10 °F to 35 °F) in combination with either traditiional wool socks or waterproof-breathable socks (Seal Skinz) and found them to be very effective at retaining warmth. I think RBH’s VB liner material is tops on the market, and very comfortable next to skin. I sincerely hope that they will explore a product line based on this technology. For the lightweight backcountry traveler venturing into colder climes, VB shirts, pants, glove, and sock liners using RBH’s technology would be a comfortable, lightweight addition to the pack.

Figure 4. Vapor Barrier Sock Liners

Note: All of our tests with RBH socks and sock liners were performed with the RBH system on one foot, and a traditional wool sock system on the other.

Elite Top Bag by Rab Carrington

Elite Top Bag by Rab Carrington

Introduction

On seemingly rare occasions, large manufacturers get a wild hair to buck the system and offer a product that is so uniquely innovative that it does little more than incite snickers and scowls from traditional backpackers so ingrained in their ways that they aren’t even willing to consider the possibilities of such innovations in design. The Elite Top Bag from Rab Carrington of the U.K. is one such example (Figure 1). The Elite Top Bag is marketed both as an overbag to extend the comfort of a lighter bag to colder conditions, as well as a lightweight 2/3 season bag. This review focuses solely on the use of the Elite Top Bag as a standalone bag.
FIGURE 1. Rab Carrington’s Elite Top Bag

The concept behind the Elite Top Bag’s design is a simple one. Insulating materials such as down depend on their ability to “loft” (i.e., trap air within their fiber interstices). Thus, since the insulation on the bottom layer of a sleeping bag is compressed by your body weight while lying down, then it effectively provides little or no insulating value (hence the need for an uncompressible foam sleeping pad for insulating the body from conductive heat loss to the cold ground). The Elite Top Bag forgoes an insulated bottom, replacing it with a single layer of open-weave mesh. The end result is a down-fill bag rated to near-freezing temperatures whilst weighing a remarkable 19 ounces!

Bag Facts

The mesh bottom of the Elite Top Bag is 22″ in width and extends 58″ from the head end of the bag towards the footbox. Consequently, the bag retains insulated “sides” and a fully insulated footbox. The size of the mesh corresponds (approximately) to the dimensions of a typical ¾-length sleeping pad, so that cool air drafts entering the mesh are (in principle) minimized. Other weight saving features on the bag include no hood with a simple drawstring-and-toggle closure (Figure 2) to control drafts in the neck and shoulders region, and no zipper, requiring the user to wriggle in and out of the bag through it’s opening at the head end.
FIGURE 2. A drawstring closure and generous shoulder girth provides a good neck seal that controls drafts and retains heat in the head end of the bag.

The Elite Top Bag is manufactured with 3-inch vertical baffles (the baffle material is an ultralight parachute nylon) spaced at intervals of 3.5 to 6.5 inches (with no obvious rationale regarding the baffle spacing!) in a narrow box construction. Approximately 7.1 oz of 750+-fill down is distributed among the baffles, which loft to a height of 2.0 inches at the baffle seams and 2.5 inches at the baffle mid-points (note that since the actual loft is less than the vertical baffle height, the Elite Top Bag can accommodate additional overfill for colder sleepers). The manufacturer suggests a temperature rating of approximately 32 °F. The shell material is a mini-ripstop (1.7-mm ripstop interval) nylon in the Pertex Microlight family (1.3 oz/yd2) of products from Perseverance Mills, Ltd. The mesh bottom is an open-weave nylon mesh with a fabric weight of 3.1 oz/yd2. The length of the bag is 67 inches, with interior shoulder, hip, and foot girth measurements (as measured) of 61 (measured at the head of the bag), 53 (measured at the midpoint), and 43 inches (measured one foot from the end), respectively. The manufacturer’s reported weight of the Top Bag is 550 g (19.4 oz). We verified the weight of our sample to be 19.00 ± 0.05 oz.

TABLE 1. Elite Top Bag Specifications

Shell Material  Pertex Microlight mini-ripstop, 1.3 oz/yd2 
Insulation  Goose Down, 750+ in3/oz 
Fill Weight (1) 7.1 oz 
Baffle Material  Parachute Nylon, 1.2 oz/yd2 
Baffle Height  3 inches 
Measured Loft (2)  2.25 inches
Footbox Loft (3)  5.0 inches
Inside Girth  61″ / 53″ / 43″
Packed Size  11 x 24 inches (264 in3) 
Total Weight (4)  19.0 oz (19.4 oz)
Notes: (1) Fill weight as reported by manufacturer. (2) Loft of top layer measured as the average of the loft measured at the baffle seams and baffle midpoints. (3) Average loft of footbox region (both top and bottom layers). (4) Weight as measured on a calibrated digital postal scale (weight in parenthesis indicates weight as reported by manufacturer).

BackpackingLight.com Position Statement:
Sleeping Bag Temperature Ratings.

Missing from this review (and for all sleeping bag reviews published here, for that matter) will be an assessment of whether or not the sleeping bag performs adequately at temperatures near its manufacturer-reported temperature rating.

There are too many variables involved that influence user comfort, including not the least, intrinsic metabolism and physiology, which vary greatly from user to user. Consider also that an individual user may sleep warm one night while sleeping cold another night, even when environmental conditions and sleep systems are equivalent, and the mere concept of temperature ratings becomes somewhat unjustifiable. Add to all of this the effects of a user’s daily caloric budget (calories consumed vs. expended), clothing worn, and amount of moisture in a sleep system (e.g., from condensation of perspiration vapor), and you have a process of such complexity that it has baffled the world’s best physiology modelers for years.

Thus, to “rate” a sleeping bag would be a hopeless exercise and to compare a manufacturer’s rating to real-world performance based on experiences of a handful of testers would not only be unfair to the manufacturer, it could possibly lead to a false conclusion by a reader that did not fit the physiological profile of our testing corps or did not experience the same conditions that we experienced in our tests. Consequently, the best we can do is to measure the loft of the bag, and ask you as an informed consumer to compare it to the loft and temperature ratings of bags from other manufacturers in order to make a wise decision.

Design Analysis

First, let’s consider a comparison of the Elite Top Bag vs. those from other manufacturers with a similar loft on their top layer (Table 2).

TABLE 2. Comparison of Elite Top Bag with Sleeping Bags
with Similar Loft of Upper Layer from Major US Manufacturers

Bag Loft (in)  Temp (ºF)  Weight (oz)
Rab Elite Top Bag  2.3 32 19
Western Mountaineering Iroquois (1) 2.0 38 24
Marmot Hydrogen (1) 2.7 30 23
Feathered Friends Rock Wren (1) 2.0 30 28
Notes: (1) Hooded mummy designs.

The data in Table 2 show that the manufacturer’s suggested temperature rating for the Elite Top Bag is within a reasonable range of temperature ratings from other manufacturers when compared to bags having a similar amount of loft on the upper layer, so it is not unreasonable to expect that the Elite Top Bag is rated appropriately. However, one should keep in mind that the presence of the mesh (which could introduce drafts or result in heat loss for a sleeper that tends to roll) and the absence of a hood should be considered to decrease the comfort of the Elite Top Bag relative to a mummy bag having a similar loft on the top layer. Consequently, the use of a hat or balaclava, and/or a sleeping bag liner or clothing, should be expected to fairly extend the comfort range of the Elite Top Bag down to its estimated temperature rating.

Performance Review

We are testing the Elite Top Bag during the period April 1, 2001 to September 30, 2001. We’ve had the opportunity to evaluate the bag on seven nights in the field during two backpacking trips and have been pleased thus far with its performance at temperatures ranging from the mid-30s to the low-50s. To date, we’ve used the bag in conjunction with a tent or bivy sack/tarp combination, both of which serve to reduce, but not eliminate, the possibility of heat loss through the open weave mesh bottom. We’ve found this to be most uncomfortable (but tolerable), of course, when temperatures were in the 30s, while the effect was not noticeable for temperatures in the 40s or higher. The draft effects were most significant in a tent, with a bivy sack being much more effective at controlling heat loss through the mesh.

The key design flaw that needs to be addressed focuses on the shape of the bottom mesh material relative to the bag. Because the mesh is a 22″ x 54″ rectangle, and because the bag is tapered toward the foot, there is not enough side insulation near the foot end of the mesh, where drafts are most noticeable (see Figure 3). We found heat loss to be most significant in the lower regions of the bag, where the testers nearly unanimously complained of cold legs when temperatures were in the 30s. Because the bag tapers and the mesh panel does not, the effect of draft-sealing “sides” decreases towards the foot end of the bag.
FIGURE 3. Bottom view of Elite Top Bag. Note the insulated “sides” and footbox, visible to the left/right, and top, of the mesh, respectively. In particular, notice the decrease in “side” insulation down the length of the mesh panel towards the footbox.

Conclusions

The Elite Top Bag certainly has one of the highest warmth-to-weight ratios of any sleeping bag on the market. We were very impressed with its ability to maintain a remarkable level of comfort given its 19-oz weight. With a few modifications (see below), it just may approach perfection for the hardy backcountry traveler who is serious about shaving ounces.

Recommendations

To overcome the effect of the mismatched shape of the mesh and bag, the bag could be rectangular, and thus, provide “sides” down the length of the mesh (see Figure 3). A rectangular bag would increase weight unnecessarily while providing a less efficient shape, so a better option would be to taper the mesh panel to match the taper of the bag (i.e., a width of 22″ at the head end of the panel tapering down to approximately 16″ at its food end). To make this work, that part of the mesh panel that was “removed” so to speak, would need to be replaced by extending the width of the down-filled baffles down the length of the bag.

Another recommendation to save weight without losing function is to replace the mesh with a lighter material, such as Pertex Microlight taffeta (1.3 oz/yd2). This would help control drafts, as the open weave of the mesh material is particularly prone to convection currents. A possible disadvantage of this modification is an increase in “slipperiness”, and consequently, less control in keeping the bag’s insulation over you.

A final recommendation to the manufacturer: provide a stuff sack with the bag that is made of silicone-coated nylon (1.4 oz/yd2), instead of the heavy polyurethane-coated nylon sack that is currently provided.

Contact Information

Rab Carrington, Ltd.
32 Edward Street
Sheffield, S3 7GB
England
Tel. +44 (0) 114 275 7544
Fax +44 (0) 114 278 0584
Email: info@rab.uk.com
Internet: http://www.rab.uk.com/ 

The manufacturer’s suggested retail price for the Elite Top Bag is £100. Rab does not sell directly to the public and currently, does not yet have a U.S. distributor. However, the Elite Top Bag can be ordered from Rock & Run, a U.K. retailer, either online or by telephone (http://www.rockrun.com/ or +44 (0) 153 943 2855).

Lightweight First Aid Kits for Hiking

Lightweight First Aid Kits for Hiking

Introduction

First, I want the reader to understand that these are only my suggestions. This article is not a substitute for advice from your own physician or other recognized authorities in first aid and wilderness medicine. Advice from this article should be compared to other resources and reviewed along with specific information about medical history and the planned activity.

Hiking is an excellent sport and exercise, whether for a short day hike, a longer walk for a few days or a week, or a long distance trek for several months. As with any sport, preparation and training help to make the endeavor fun and safe. As with any sport, injuries, accidents and illnesses will occur. In general, a first aid kit should be part of your survival gear and always available for hikes. It is a good idea to keep a kit for all general activities as well as one that is targeted to specific endeavors. For instance, you don’t need the same gear for water skiing as you might carry for a spring walk in the Smokies. However, there are several basic items that you will want to have, at least on your person. You can compare this to how you carry your driver’s license while driving to the corner store, carry a Voter’s Registration card when voting, carry a Passport when traveling to Paris, and carry a driver’s license, Social Security card and proof of citizenship to a new job.

Identification

So let us begin with the basic ID. Grab a 3×5 card and write your name, address, phone numbers, identifying numbers, insurance numbers, next of kin, and a list of illnesses and medicines you take. Then in RED, write your allergies. Laminate this card. This card stays on you all the time.

Packaging

Next, find something to carry your first aid kit in. Look outside the envelope. For instance, you might want to put ID, a few bandaids and Aspirin in a film canister that you keep in your pocket, or attached to a lanyard about your neck with your compass and whistle. This container needs to be small, light, and easily carried. The container should be in your possession for every short walk to get water, use the toilet, sight see, or other activity.

For more involved first aid, a larger package (Ziplock bag, soapbox, or other small container) should fit into your pack and will contain more significant gear. It should offer convenient access and never be buried in your pack. Wander around the grocery store, pharmacy, or your basement to find just what you will need. Some are able to make a small box work, keeping it in a pocket. Others will feel the need to keep a kit that requires a fanny pack. If you do much winter or off road travel, you may want to consider keeping a larger kit in your trunk that would include a shovel and more heavy and bulky gear for treatment of trauma or basic CPR.

In my case, I use Ziplock bags. I like the firm quart size that will stand independently. (A sturdy plastic bag can double as an emergency water container). Because it is clear, you can take quick inventory of your first aid resources. A sandwich baggie might be worth bringing to help contain ticks and other nasties you might find attached to you, and want to take to your doctor or ER if you become ill-having a specimen handy may aid in the diagnosis of a tick borne infection.

Contents

I like to keep essentially two kits. The one attached to me will provide essentials if I lose my pack. This is a small Ziplock, jar, or film canister attached to a lanyard with a compass, mirror, LED light and whistle. This kit also contains the ID card. I might put a Mylar blanket in this container, just in case I need emergency shelter. Two large black trash bags can also serve this purpose, and will collapse to a very small size. I also put a BIC lighter in the kit. This part of my kit gives me emergency shelter, ID, medical information, three means of signaling for help (mirror flashes, light flashes and the whistle), as well as means to start a fire. I also attach large safety pins to my zippers. These help attach slings and splints made from clothing, bandanas and other gear, and double as a convenient zipper pull.

The larger Ziplock bag or other container will sit in the top compartment of my pack. This bag will also contain prescription medicines, along with labels from your pharmacy to identify and confirm that you are in possession of medications and not diverting prescriptions for abuse. Some pharmacies provide a service to pack medicines in individual dose packs, which helps prevent breakage, spoilage, water damage, and aids identification. Avoid the usual fragile pill bottle that will allow humidity (which dramatically reduces the shelf life of your medicine) and crushing of contents. Consider using a ball of cotton soaked in Vaseline to reduce breakage, as well as means for cleaning a wound, starting a fire, or other use. A small magnifying glass can give you an additional way to make a fire, as well as a means to check a wound or search for ticks. There should be a small notepad that details the contents of the container, numbers and types of medicines, and can be used to keep a chronology of treatment, along with a small pencil. You should make a few choices about non-prescription medicines such as Aspirin or other analgesics, vitamins, GI remedies, electrolyte replacement powder, salves, lotions and other agents. Personally, I carry Aspirin, two moderate strength oral narcotic tablets, pink bismuth tablets (Pepto Bismol), Tums for daily calcium supplement, and possibly one or two sleeping tablets. An antihistamine, such as Benadryl, can help treat reactions to allergies or insect bites and stings.

Next I include trauma and injury supplies. Think about what accidents and conditions may occur on your walks. I divide these into two groups. First, let’s consider minor inconveniences that make the walk difficult but can be tolerated. These include abrasions, blisters, sunburn, dehydration, insect bites and stings, and other minor traumas or conditions. Get two pairs of latex gloves and use them to contain each other. In the fingers of these gloves put your minor injury supplies such as bandaids, moleskin, Compeed or other bio-occlusive dressing, butterfly strips and other wound dressings. Add to this small tubes or packets of salves such as triple antibiotic creme, diaper creme, sunblock (often included in skin lotions), DEET or other insect repellant.

The second group deals with potential trip ending events such as burns, lacerations and orthopedic injuries. Grab your choice of 3-inch gauze roll, Ace Bandage, 4X4 pads, sanitary napkins and other wound dressing. Add to this either a small roll (10 feet) of Duct tape or bandage tape. I keep more duct tape rolled around my hiking poles. You might want to carry a small amount of Saran Wrap, which can be an excellent temporary burn dressing. You could carry a SAMS splint, but remember that hiking poles and mattress pads can do a very good job of splinting with duct tape, with torn clothing, safety pins, or rope to keep the splint in place. You should also arm yourself with basic first aid education regarding lacerations and musculoskeletal injuries, and not just a book to thumb through during a crisis. You should make decisions about carrying snakebite equipment, remembering that the old advice of cutting, sucking out poison, and such are now considered to be very ill advised.

Finally, consider what you might need for other life support. Iodine tabs or solutions can help clean wounds and treat water. Are you prepared to provide mouth-to-mouth resuscitation, or will you carry a barrier to protect you from a potentially infected and non-responsive victim? Do you feel the need to carry snare wire or fishing gear to obtain food? Do you understand the need to get a hypothermic person out of wet clothing, even if only to put them into large trash bags to warm up?

One can find multiple uses for first aid items and the means to improvise with what you already carry or wear. Many find they can do well with only ID, a few bandages and limited medication and lotions. Most find their own comfort level with the decisions of what gear to bring or to leave behind. There is little need to carry a first aid kit that would provide all the functions of an urban paramedic’s kit. Regardless of what you bring, make sure you know how to use it. Take the time to learn basic first aid for the major maladies of the trail. This knowledge should include recognition of hypothermia and hyperthermia, dehydration, fever, infection and shock. One should have knowledge of how to stabilize a potentially fractured limb, how to stop bleeding, and how to manage burns, insect bites and other injuries.

A well-stocked mind will make a well-stocked first aid kit out of items at hand.

Editor’s Note: Dr. Thornoloe’s last statement couldn’t ring more true to a lightweight backpacker. The keys to minimizing the weight of your first aid kit include an increased base of knowledge that allows you to use other equipment items to treat major injuries, and accepting the possibility that minimizing your first aid supplies may result in ending your trip early due to an inability to treat a normally minor injury. Also, one must keep in mind that the need for rescue and survival equipment depends largely on your hiking locale. In most places in the lower 48, carrying survival equipment can usually be replaced by participation in a good wilderness survival curriculum; however, the importance of rescue (signaling) equipment cannot be emphasized enough. With a life-threatening injury, nothing is more important than getting the victim out of the wilderness FAST. This need alone may justify carrying items like a cellular telephone, signal flare, strobe light, or red smoke bomb.

The Arc Bag Concept: Saving Weight with Variable Girth Sleeping Bags Having an “Arc” Shaped Cross Section

As we prepare to announce the launch of the Backpacking Light website, it is probably appropriate to introduce a teaser about what we intend to spend a great deal of time with this year: clothing and sleep systems for ultralight hiking, with a focus on quilts.

Editor’s Introduction

As we prepare to announce the launch of the Backpacking Light website, it is probably appropriate to introduce a teaser about what we intend to spend a great deal of time with this year: clothing and sleep systems for ultralight hiking.

This editorial provides some insight into the concept of the ARC BAG: a variable girth sleeping bag having an arc, rather than an elliptical (or oval), cross-section. Come along for the ride, we think this concept will constitute a leading edge in sleeping bag design in the coming years.

Enjoy, and get ready to ‘lose some weight’!

Overview

Conventional sleeping bags are manufactured with an elliptical (or oval) cross-section (at least, that is the approximate cross-section of a bag occupied by a user).

It has long been known that the insulation beneath you is compressed while sleeping, and thus, may not be as effective in maintaining warmth in the bag while sleeping.

Both Rab Carrington (UK) and Macpac (New Zealand) have recognized this and are manufacturing so-called “top” bags, i.e., sleeping bags that only have insulation along the top and sides, and simply a fabric sleeping pad sleeve (in the case of MacPac) or a single layer of fabric (in the case of Rab) for the bottom.

However, such designs, and in fact, most sleeping bag designs, suffer from a fundamental flaw that has been recognized and promoted by Ray Jardine beginning in the late 1990s: girth cannot be controlled, and insulating efficiency is lost.

Enter the Quilt

And so, we have the ‘sleeping quilt’. The quilt is just that – a sheet of insulated material, not unlike your bed comforter at home, that you simply lay over you. On cold nights, you grab the edges, and tuck them under you. Guess what you are doing when you do this? That’s right – changing the interior girth of the bag to increase its insulating efficiency.

Do-it-yourselfers are realizing the benefits of quilt designs, creating “variable girth sleeping bags” with sewn foot boxes and open bottoms, where the sides can then be tucked beneath you on colder nights.

Advantages of Variable Girth Sleeping Bags

The primary advantage of variable girth bags is that you can adjust your insulating clothing underneath and extend the bag to a wide range of conditions and seasons. This is economical (you may only need one bag), and you can layer two ultralight variable girth bags together to extend temperature ranges or move the dew point (and condensation) into the outer layer (something that is more difficult to do with conventional sleeping bags). The resulting bags are lighter (lack of bottom insulation and hoods save weight and give you more flexibility for integrating your sleep system with other components, such as hooded jackets, hats, sleeping pads, etc.).

The Arc Cross Section

The ability to escape the confines of the “ellipse” and enjoy the freedom of the “arc” cross section gives ultralight hikers and climbers tremendous versatility, as outlined above. Arc-cross-section bags will evolve as a category, although manufacturers will likely drag customers kicking and screaming for a few years, because they will face the emotional barriers that consumers hide behind, the most common of which is the psychological security of being wrapped up, head to toe, in a draft-free down cocoon.

Arc designs are available on the Internet for the do-it-yourself crowd. One of the best has been published by Hungry Howie (historical reference: http://www.newsushi.net/quilt.html). Howie is an experienced thru-hiker of the Appalachian Trail, and to our knowledge, is the first to put the variable girth, sewn-foot box arc design into action (November 2000). He will be using the quilt this year in adventures that include a thru-hike of the Long Trail. We’re eagerly awaiting his report!

Update (April 2003): Don Johnston has additional thoughts on the variable girth arc design. An experienced user of the Rab Top Bag, Don has issues with it, most of which are largely related to its lack of variable girth functionality. In an email to the BackpackingLight Yahoo eGroup, Don describes the elements of what may be an ideal sleeping bag design:

“These are the specs I developed for an alternative to the RAB top bag that should work better for me: Picture in your mind a sleeping bag with a full length zipper that is open and the open side is facing down so the bag is a quilt over me. Start with a sleeping bag like the PHD Minimus or Nunatak Alpinist. If using the Alpinist request it be constructed with a 2″ baffle height and 4″ baffle width. Open up this zipper less bag soon to be quilt except for a 10 to 12 inch foot pocket. The quilt is open for the remainder of it’s length. No Zipper, Mesh, or other closure. The width of the quilt tapers from the foot box to 45″ wide at the hip which is 39″ from the foot end of the Quilt. The width remains 45″ wide for the remainder of the quilt. No hood. The head end of the quilt has a velcro tab to close the top of the bag and the top of the bag is encircled with a draw cord and toggle that is adjustable on the top side. This allows closing the bag off at the neck. Microlite shell fabric. 8 oz of 800 fill down or more up to a total bag weight of 17 oz. The bag can be held down to a pad by adding a string to each side of the bag at hip height. The string is simply tied under the ground pad. An alternative is grosgrain ribbon and velcro.”

In essence, Don has taken the best features of top bags (insulation on sides and bottoms), and the variable-girth flexibility of quilts, and engaged an arc design with bottom cords/straps. We think this may approach an ideal design for lightweight hikers, and are looking forward to the fruits of his efforts. Last we heard, Don solicited a few manufacturers to make this custom design for him. We hope the design becomes commercially available. I know my pocketbook is ready.

Perhaps Western Mountaineering, a manufacturer of Cadillac down bags for backcountry enthusiasts, will adopt the concept. Could we see an “Arc UltraLite”, “Arc Dakota”, or “Arc Puma” in the near future? (Answer: not soon enough).

Using the Arc Design with a Sleeping Pad

The Jardine concept of an arc design employs the edges of the bag mating with the edges of a closed cell foam pad to regulate the ground seal. The problem with this design is that forcing the edges of the bag to mate with the edges of a sleeping pad eliminates the variable girth flexibility of the system, and you are left with a traditional elliptical cross-section that is unable to accomodate various layers, and thus, the system loses insulating efficiency for the underdressed sleeper on a cooler night (more volume of dead air in the sleeping bag to heat).

Others (including Johnston) have proposed using the sleeping pad inside the bag, with the edges of the quilt tucked underneath. Johnston proposes using straps or strings to secure the edges of the bag underneath the pad. The main advantage of this technique is the ability to fully seal the sides of the bag where it reaches the ground, minimizing drafts. The main limitation of this technique is that the pad forms a semi-rigid bottom that, unless as narrow as the body, can cause compression of the down near the sides, and cold spots. For pads that are greater than body width, the ability to create an efficient arc-shaped cross-section around the user is impaired by the semi-rigid pad, and more volume than necessary is created for the user to heat up.

A final alternative is to secure the bag edges (using Johnston’s proposal of straps or strings) above the pad, so that the bag’s girth can be more precisely controlled around the user and the excess interior volume is minimized, making for a very efficient insulating system. The main disadvantage of this technique is that when the sleeper rolls, if s/he rolls with the sleeping bag, the bag’s open bottom gaps will be exposed to drafts.

Summary

The following table summarizes the features of arc vs. elliptical cross sections for sleeping bags.

Table 1. Comparison of Arc (Variable Girth) vs. Elliptical (Fixed Girth) Sleeping Bags

Cross Section Arc Ellipse
Girth Variable Fixed
Hood No Sometimes
Bottom Insulation No Sometimes
Weight Lighter Heavier
Commercial Availability Limited Widespread
Do-it-Yourself Ability Easier More difficult
Overbag Layering Layers well as an overbag Must be oversized to layer as an overbag
Clothing Layering Layers well with winter insulating clothing Must be oversized to layer with winter clothing
Warmth Draft protection is compromised by lack of hood and bottom insulation Drafts can be sealed better with a hood and fixed fabric elliptical (closed) shell

Credits

Many thanks to Hungry Howie, Don Johnston, and Ray Jardine for their efforts in advancing the concept of arc-cross-section sleeping bags and variable-girth quilts.

Updates

August 2001 – Don Johnston has successfully convinced a manufacturer, Nunatak Gear, to bring his design to market! Don’s bag weighs around 18 ounces, is reported to have 2.5 or so inches of single-layer loft (800 fill down) and uses the 0.85 oz ultralight nylon similar to that used in the Western Mountaineering ExtremeLite series bags. The design, presumably, was a derivative of Nunatak’s “Alpinist” bag, and they’re calling the new design the “Arc Alpinist”. Hey, we like the name; what can we say?!

November 2001 – Well, I bit the bullet too and had Nunatak customize an arc-section variable girth down bag for me. Microlight shell, 0.85 oz lining, with a few unique specifications that I asked for: differential cut (for which I specified the exact differential), variable down fill across its length (more in the foot area, less in the chest area, so the bag is ideally combined with an insulating jacket), and a slightly wider “expedition” cut so it can be used as an over bag over a smaller down bag. Overall, I’m very happy with it and expect that it will take me down into the single digits easily. I wrote a more complete review for BackpackGearTest (historical reference: http://www.backpackgeartest.org/reviews/Sleep%20Gear/Sleeping%20Bags/Nunatak%20Arc%20Alpinist%20Down%20Sleep%20Bag/Owner%20Review%20by%20Ryan%20Jordan/).

July 2002 – Don provides a comprehensive description and review of his arc-cross section variable girth sleeping bag. Read it here.