Field Report:
Montbell Ultralight Alpine Down Hugger #3 Sleeping Bag

MontBell Ultralight Alpine Down Hugger #3 Sleeping Bag  (photo from MontBell website)

Product Information
Manufacturer: Montbell
Manufacturer Website: http://www.montbell.com/
Product Tested: Montbell Ultralight Alpine Down Hugger #3 Sleeping Bag
Year of Manufacture: 2006
Color: Balsam (blue-green)
Sizes Available: Regular for users to 70 in (178 cm) , Long for users to 76 in (193 cm)
Size Tested: Long
Weight Listed: 22 oz (624 g)
Measured Weight: 21.15 oz (600 g) (scale accurate to 0.01 oz/0.1 g)
Fill Weight: 10.6 oz (301 g)
Stuff Sack Weight: 0.85 oz (24 g)
Inside Shoulder Girth:  48.2 in (122 cm) relaxed, 64.2 in (163 cm) expanded
Inside Knee Girth: 38.4 in (98 cm) relaxed, 51.2 in (130 cm) expanded
Packed Size: 5.3 in x 10.4 in (13.5 cm x 26 cm)
MSRP: $255 US

Product Description
The Montbell Alpine series is their lightest and most compressible sleeping bags. The Ultralight Alpine Down Hugger #3 is a down-filled sleeping bag rated at 32 F (0 C). For further product information see my Initial Report.

Test Description
Test Period—Mid-April to mid-August 2006.

Test Locations—Southwestern US (Colorado, Utah, New Mexico, and Arizona).

Testing Conditions—The testing environments consisted of: canyon country, forests, and alpine terrains. Elevations ranged from 5,000 to 12,500 feet (1,524 to 3,810 m). Extreme conditions included: strong winds, dust/rain storms, heavy rain, low temperatures, and high elevations with strong UV and intense thunderstorms. I tested the bag at temperatures both above and below its temperature rating, and in wet and dry conditions.

Activities—The Montbell Ultralight Alpine Down Hugger #3 Sleeping Bag was tested while backpacking.

Use To Date—In the first two months of testing I have used the Montbell Ultralight Alpine Down Hugger #3 Sleeping Bag on eight backpacking trips totaling 21 days (13 nights). Nighttime temperatures ranged from 22 to 45 F (-5.6 to 7 C). The shelters I have used it in so far are a Tarptent Rainbow single-wall tent, a Six Moon Designs Gatewood Cape, and a Big Sky Products Evolution 2P double-wall tent.

Data—On each trip I recorded the following data in relation to my comfort sleeping in the Montbell Alpine Down Hugger #3 Sleeping Bag: 1) temperature in my shelter and outside, 2) estimated wind speed, 3) estimated humidity, 4) altitude, 5) precipitation (including what form), 6) sleeping system the Montbell Ultralight Alpine Down Hugger #3 Sleeping Bag was used in, 7) clothing worn inside the bag, and 8) how well it performed in terms of warmth, utility, and comfort.

Evaluation
Below are specific factors on which I am evaluating the Montbell Ultralight Alpine Down Hugger #3 Sleeping Bag. As the test progresses, I will answer the questions I raised in my Initial Report, and update information as needed.

Materials, Quality, And Construction—The Ballistic Airlight^™ hollow fiber calendared nylon shell is really impressive. It’s very lightweight and has a soft feel, yet is durable and downproof. I looked over the quality of the sewing details, and found that the bag is very well made.

Sizing—According to Montbell, the size Long bag will fit users up to 6 feet 4 inches (193 cm), and I agree. I am 6 feet tall (183 cm) and there is plenty of length to spare. Montbell specifies that the shoulder area will stretch out to a girth of 64 inches (163 cm). I slept in the bag while wearing a down jacket and with a synthetic jacket and found the girth ample to accommodate extra clothing. I have not experienced any down compression from the bag being too tight.

Features—Although this is an ultralight sleeping bag, it still has several useful features: full-length zipper with double sliders, down-filled draft collar behind the zipper, hood with drawcord closure, elastic seams that draw the sleeping bag around the body, and a drawcord closure at the foot. The bag does not have an interior pocket or a neck draft collar.

Usability—The horizontal seams have elastic stitching that causes the bag to contract and hug my body when I am inside. I found it easy to move inside the bag, with the bag easily expanding to accommodate my movements.

In my opinion, the stuff sack provided with this bag is too small. It takes a lot of effort to stuff the sleeping bag into the small sack, and then there is a second drawcord to pack it down even smaller! Montbell promotes the compressibility of this bag so it takes up little space in a backpack. However, I personally feel that too much compression damages the down, and would prefer to use a slightly larger stuff sack. After the test is completed I will definitely go to a larger stuff sack that the bag will more easily pack into (however it will take up more space in my pack).

The shoulder girth of this bag expands to 64 inches (163 cm), which is very roomy and provides lots of space to wear additional clothes inside the bag to extend its warmth. The “hugger” feature appears to be a good approach to offer a sleeping bag with plenty of girth to accommodate people of different sizes, yet pull the down close to the user’s body for extra warmth.

The full-length zipper operates fairly smoothly for getting in and out of the bag. It snags occasionally (especially on some labels midway), but overall it snags less than other ultralight bags I have used. There is a small Velcro tab at the top of the zipper to keep the zipper from opening from my body movements. However, I found on several occasions when wearing an insulated jacket inside the bag that the tab does not hold and the zipper opened when I turned over. It helps to squeeze the tab to make the Velcro grip better.

I personally feel that a full-length zipper is overkill on an ultralight sleeping bag. For my backpacking conditions (western mountain and desert camping, usually in cool weather) I would be perfectly happy with a half-length zipper or no zipper.

The hood is ample sized and covers my face down to my mouth when drawn. There is plenty of room inside to accommodate wearing a warm hat. The drawcord does not operate as smoothly as I would like. I suggest using a slightly smaller diameter and smoother cord for the mini-cordlock that is used.

Insulation and Loft—To measure the bag’s loft I thoroughly shook the bag vertically and horizontally, then laid it on a table for 24 hours to allow the down to fully expand. Then I held a yardstick horizontally over the bag at several locations and measured its double-thickness loft with a ruler. The average double thickness loft was approximately four inches (10 cm). Dividing by two, the single thickness loft is approximately two inches (5 cm). The bag has vertical baffles to hold the down in place, so it does not have any capability to re-distribute the down (as with continuous baffles) to increase the loft on top. When I held the bag up in front of a strong light I discovered that several compartments (especially in the torso area) contained very little down. 

When I held the sleeping bag in front of a strong light, I discovered that several chambers (especially in the torso area) have very little down in them. The photo also shows the bag's elastic seams that enable the bag to hug the user's body.

With only has two inches (5 cm) of loft, its temperature rating is somewhat optimistic (in my opinion) in terms of the weight of down in the bag (10.6 ounces/301 g) and measured loft. It appears that the bag is a little skimpy on down and loft, and would benefit significantly from the addition of another ounce (28 g) of down. For an expensive ultralight sleeping bag, 725 fill-power down is low by today’s standards. In my opinion, Montbell should consider using at least 800 fill-power down, and/or increasing the amount of down in the bag to 12 ounces (340 g).

When I weighed the bag, I found it to be 0.85 oz (24 g) lower than specified, and reported in my Initial Report that it was underweight. I subsequently figured out that the stuff sack weighs exactly 0.85 ounces (24 g), so I conclude that the manufacturer’s specified weight is the weight of the bag plus the stuff sack. 

Comfort/Warmth—In the field, I have used the Montbell Ultralight Alpine Down Hugger #3 on eight backpacking trips so far, with a total of 13 nights. Temperatures ranged from 22 to 45 F (-5.6 to 7 C), with three nights (22, 28, and 29 F/-5.6, -2, and -1 C) below the bag’s 32 F/0 C temperature rating. While sleeping in a well-ventilated shelter I found the bag to be warm (for me) down to about 38-40 F (3-4 C), while wearing microfleece long johns and a warm cap inside the bag. On cooler nights down to freezing I also wore a synthetic insulated jacket inside the bag. On the coldest night I wore a down jacket and synthetic insulated pants inside the bag to stay warm.

I found the bag seals up very well to trap heat, and did not detect any drafts around the zipper or hood. The thinly insulated areas in the torso area contributed to an overall chilly feeling when the temperature dropped to around 38-40 F (3-4 C). From my experience so far, I conclude that the Montbell Ultralight Alpine Down Hugger #3’s minimum comfortable temperature (for me) is around 40 F (4 C), and that the bag is overrated by about 8 degrees F (4 degrees C). However, as I noted above, because of the bag’s roominess, it is easy to wear additional insulated clothing inside the bag to extend its warmth down to about 25 F (-4 C) or so.

Water Resistance—The bag’s shell fabric has a Durable Water Repellent (DWR) treatment that really repels water. I put some water in a small depression on the bag and let it stand for an hour and it did not soak through. However, the seams are not seam sealed, so water will soak through the stitching.

On my most recent backpacking trip, it rained in the evening, then cleared overnight allowing the temperature to drop to 29 F (-1 C). I had lots of frost on the outside and inside of my shelter (Gatewood Cape), and the Montbell bag was quite damp on the outside. Its surface DWR treatment did an excellent job of keeping the moisture from soaking into the bag. The bag retained its loft and I stayed warm.

Breathability—The shell fabric appears to be very breathable and allows moisture to pass through. I have not yet used the bag in some prolonged wet weather, so I don’t have any information on its tendency to accumulate moisture under high humidity conditions.

Durability—So far, the bag’s shell fabric has been adequately durable for normal backpacking conditions, with no snags or punctures whatsoever. I have repeatedly stuffed the bag in a stuff sack and its loft springs back to original proportions each time. I will re-measure the bag’s loft at the end of the test.

Suitability For Ultralight Backpacking—The Montbell Ultralight Alpine Down Hugger #3 at 21.2 oz (600 g) is definitely compatible with ultralight backpacking. It is roomy enough to wear additional clothing inside to extend its warmth. However, I would readily give up the full-length zipper in exchange for an extra ounce of down.

Acknowledgement
I would like to thank Montbell and the BackpackGearTest Group for selecting me to participate in this test.

Will Rietveld