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Reviews > Sleep Gear > Summer Bags and Liners > Montbell ULAP Thermal Sheet > Test Report by David Heyting
Name: David Heyting
Height: 6’ 0”, 1.83 m
Weight: 205 lb, 93 kg
City, State, Country: Snoqualmie, Washington, USA
I have been hiking and backpacking for over 15 years. A great deal of the backpacking that I do is related to mountaineering and rock climbing in the Pacific Northwest. When not climbing, I’m a hiker that tries to go light in order to push more miles. My main areas of exploration are the Washington Central and North Cascades, but have done lots of hiking in the British Columbia Coastal Range as well as the Oregon Cascades. I am also an avid adventure racer and compete in several races each year ranging from 2 hours up to 24 hours in duration. .
July 23, 2007
Model: ULAP Thermal Wrap Sheet
Listed Weight: 14.5 oz. / 411 g
Measured Weight: 15.2 oz / 431 g
Listed Max User Height: 5’10” / 1.78 m
MSRP: $180.00 US
The Thermal Sheet is an ultra-light summer sleeping bag. It is rated as a 50 degree (10 C) stand alone bag or it can be used as a way to add some insulation to another sleeping bag by using it as a sleeping bag liner. It features 800 fill power down and is constructed with Ballistic nylon. Per Montbell's website, Ballistic nylon is both ultra-light and ultra-thin however due to its tight weave the fabric has a high wind resistance value and feels silky soft. The nylon is also more abrasion resistant that other similar weight fabrics. The fabric is then treated with Montbell’s POLKATEX treatment, which according to the manufacturer, makes the sheet water-repellent. The bag is designed for users not taller than 5’10” (187 m). It comes with a stuff snack and has a listed weight of 14.5 oz (411 g). The stuff sack features a two drawstring system so that the bag can be completely protected when stuffed by the sack.
ULAP Thermal Sheet - Photo Courtesy of Montbell
The first thing that jumped out at me was the size. It is small! It definitely meets my definitions of an ultra-light bag. When I measured the bag it came up a little bit heavier than the listed weight, however it is still less than a pound. The bag was also easy for me to stuff and re-stuff; it was not an item that makes me wonder how they ever got the item to fit in the stuff sack. The dual drawstring is a nice feature in my book, as it will hopefully prevent a portion of the bag from getting damaged by sticking out of the stuff sack. This size makes is a potentially great choice not only for a summer bag, but also as an emergency blanket during a long day trip or when climbing above the snowline
The fabric was also extremely soft and very comfortable to sleep on. I already spent a night in the bag and was very happy with the comfort. The down fill also seems to uncompress quickly which adds to a quality night’s sleep. I will watch this during the testing period to make sure that this remains the case.
Based on the manufacturer’s recommendations, I am pushing the size of the bag. The bag fits pretty snug, however I still feel like I have enough room to move for a comfortable night’s sleep. However I would recommend that users stick to the manufacturer's suggested user size. This may not be as big of an issue if the bag is used as a liner, I will have to look into this as well. The zipper is easy to access and to zip myself in the bag. The bag also has a Velcro flap to keep the zipper from opening.
Thermal Sheet packed up and ready to go
I was able to take the Thermal Sheet with me three trips during the testing period. The first was a five day Expedition length adventure race that started in Bozeman, Montana. The race went into the Bridger Mountain Range as well as the Gallatin Mountain Range. During the race I covered over 90 miles (145 km) on foot and over 130 miles (209 km) on bike. The lowest temperatures that I faced while trying to sleep during my trip in Montana were in the low 40’s F (4 C). I used the Thermal Sheet on four separate occasions while sleeping during the race. Three of the four times I used just the Thermal Sheet (exposed to the elements) on a blow-up sleeping pad. The fourth time I actually slept in a chair, using the Thermal Sheet more like a blanket. The Next trip that I used the Thermal Sheet on was during a 27 mile (43 km) trek, in the Central Cascades. I stayed mostly on the Pacific Crest Trail during my trip. I used the Thermal Sheet while taking a “nap” waiting for the sun to rise. I would guess the temperatures during my “nap” were in the mid to upper 40’s (7C). In this instance I used the Thermal Sheet like a blanket. The final trip was to Lake Cushman, which is on the Olympic Peninsula of Washington State, where I spent two nights in the Thermal Sheet. Nighttime temperatures where in the lower 50’s (10 C). I slept one night on just a tarp on a trail and the other night I was in a campsite. In each of these experiences, I slept exposed to the elements, without a tent or a bivy sack.
Initial Likes and Dislikes:
Likes: The weight (or lack thereof)!
Dislikes: Nothing so far!
October 2, 2007
Field Conditions and Locations:
I was able to take the Thermal Sheet with me three trips during the testing period. The first was a five day Expedition length adventure race that started in Bozeman, Montana. The race went into the Bridger Mountain Range as well as the Gallatin Mountain Range. During the race I covered over 90 miles (145 km) on foot and over 130 miles (209 km) on bike. The lowest temperatures that I faced while trying to sleep during my trip in Montana were in the low 40’s F (4.4 C). I used the Thermal Sheet on four separate occasions while sleeping during the race. Three of the four times I used just the Thermal Sheet (exposed to the elements) on a blow-up sleeping pad. The fourth time I actually slept in a chair, using the Thermal Sheet more like a blanket. The Next trip that I used the Thermal Sheet on was during a 27 mile (43 km) trek, in the Central Cascades. I stayed mostly on the Pacific Crest Trail during my trip. I used the Thermal Sheet while taking a “nap” waiting for the sun to rise. I would guess the temperatures during my “nap” were in the mid to upper 40’s (7.2 C). In this instance I used the Thermal Sheet like a blanket. The final trip was to Lake Cushman, which is on the Olympic Peninsula of Washington State, where I spent two nights in the Thermal Sheet. Nighttime temperatures where in the lower 50’s (10 C). I slept one night on just a tarp on a trail and the other night I was in a campsite. In each of these experiences, I slept exposed to the elements, without a tent or a bivy sack.
My bed setup with the Thermal Sheet on a tarp
Based on my first two months using the Thermal Sheet, I found the manufacturer’s recommendations to be very accurate in terms of how to best use the Thermal Sheet. When I stayed within the manufacturer’s recommendations I was extremely happy with the performance of the Thermal Sheet. For temperatures below 50 F (10 C) I did find myself waking up cold and needing to add clothing to sleep comfortably. I would start off feeling warm and comfortable in the bag, however once my core temperature would fall as I slept I would find myself waking up cold. However at warmer temperatures I was able to sleep comfortably with just the Thermal Sheet exposed to the elements.
I am just over that limit, however I was able to squeeze into the bag, thus I do not think that had any negative impact on my experience with the Thermal Sheet. The bag provided me enough room to move around during the night. The bag also features a Velcro strap to keep the zipper from opening up in the night. I found this to be a nice feature. During one of my nights near Lake Cushman, I did experience some mist. The bag was damp, but seemed to perform just as well as it did prior to being wet. However I would not consider that an extreme test of how the bag handles while being wet.
I actually found that my favorite use of the Thermal Sheet was to use it like a blanket. During my race in Montana, when coming into a transition area, I would continually wrap myself in the Thermal Sheet to keep warm. It proved to be a great asset when using it in this fashion. The zipper on the bag is designed so that you can fully open the bag into a big sheet. I found myself constantly using the Thermal Sheet during periods when I was resting to keep myself warm. I found it easy to pull out use and then re-stuff. Also when fully un-zipped I was able to stuff two people under the sheet. This proved to be useful while trying to keep more people than just myself warm.
When using the Thermal Sheet as intended, I found it to be a great asset to a summer trip or even a colder trip to provide additional warmth in a very lightweight package. For warmer summer trips, the Sheet is a great option as my main sleeping bag. It is also a great blanket to use in and around camp. For someone like myself, who does some long trips that includes hiking through the night with very little sleep, the Thermal Sheet is a great insurance policy to have with me in case of emergencies, such as injury or unexpected weather which could cause me to have to set up an unexpected camp. Do to the usefulness of the bag in this manner, I have actually found myself carrying the Thermal Sheet on trips that prior to this test I just would not have taken a sleeping bag with me. This has provided me with a much greater piece of mind during long unsupported trips.
Items for Continued Testing:
I intend to use the Thermal Sheet as a bag liner for some upcoming winter trips to see how effective the bag is under those circumstances. I really like the idea of carrying it during cold weather to use as blanket around camp as well as a bag liner. I also plan on testing it more thoroughly with a bivy sack and a tent to see if using it in conjunction with a bivy or tent would allow me to sleep comfortable at colder temperatures. During my use in the Field Report period, I basically just slept with the Thermal Sheet Exposed to the elements.
Field Likes and Dislikes:
Likes: Likes: Using it as a blanket.
Dislikes: Nothing so far!
November 30, 2007
Aside from carrying the Thermal Sheet in my daypack and using it as a blanket on longer hiking trips (it accompanied me on three outings that were 16 miles (25km) in length), I was able to use the Montbell Thermal Sheet as my sleeping bag on two more nights. The first was a trip into Alpine Lakes Wilderness, during which I set up camp prior to a 16 mile (25km) trip. I used the Thermal Sheet as my main sleeping bag for this night. I slept on an insulated sleeping pad and was in a four season tent. The overnight temperature dipped to the upper 30’s (around 3 C). The second trip was trip a short overnight trip again to the Alpine Lakes Wilderness in the Central Cascades. On this trip I used the Thermal Sheet as a bag liner for my 30 (0 C) degree rated sleeping bag. The low temperatures were in the upper 20’s (around -2 C). For this trip I was again in a four season tent sleeping an insulated sleeping pad.
Unlike my nights spent in the ULAP Thermal wrap during the Field Testing period (please refer to the above Field Test section), in which I slept exposed to the elements, during the long-term testing period I spent my nights sleeping in a tent and on an insulated pad. I am very positive that the tent had a big impact on how warm I felt, as the temperatures for these nights were much colder than I experienced during the field test. Yet, I felt much warmer during the night which has to do with being enclosed in a tent and not exposed to nature. However I did sleep with more layers on than I would have if I had been using a higher rated sleeping bag. I was worried based on my field experience that I might wake up cold as I did in Montana, however I found that I slept just fine.
I was also able to use the sheet as a liner for during one of my nights. I actually found that by doing this it made my sleeping bag extremely warm. I was actually awoke in the night and found myself being actually too hot. However I am typically a pretty warm sleeper and was in temperatures that were just outside the range of the sleeping bag used as my main bag. Using the sheet as a liner does increase the warm of a sleeping bag greatly. Based on my limited use of the bag in this manner I would have a hard time listing how many degrees I felt the Thermal Sheet used as a liner would add to a sleeping bag. However I will say that using the Thermal Sheet and another lighter weight and higher degree rated sleeping bag, may have it merits. Especially when trying to decide whether to take a heavier bag on a trip. This would allow the ability to sort of mix and match based on the weather and temperature to find the optimal sleeping arrangement. Granted based on my experience I am unsure if the using two bags would provide me with the same warmth that my negative degree bags does, however if I use the Thermal Sheet with my 30 degree bag it is .5 lbs (.23 kg) lighter than my negative degree bag. Plus there is the added bonus of using the Thermal Sheet as a blanket around camp and not worrying about getting your main sleeping bag wet or full of dirt and grime.
I plan on using the Thermal Sheet as a main sleeping bag for warmer temperatures and as a blanket on some of the longer hiking trips that I do. It has become a saving grace on some of the longer training trips that I do training for adventure races as it provides me with a great way to keep warm and provides something that could be very valuable during an emergency. I also plan on using the Thermal Sheet as a liner and extra camp blanker during winter camping trips. Thus I will have the option of using it as a blanket while hanging out around camp. The added weight is very minimal for the functionality that I gain by carrying the Thermal Sheet, thus it makes it an easy decision for me to carry the Thermal Sheet on most of my trips.
All in all the ULAP Thermal sheet is a well constructed summer sleeping bag that also doubles as a camp blanket. The bag performs very solidly as a sleeping bag when sticking to the manufacturer’s recommendations and is used for warmer nights. It makes an incredible addition for long hikes or nighttime hiking were stopping to take a nap might be beneficial. Based on my testing, the bag performs best when used as a camp blanket for extra warmth. The Thermal Sheet is lightweight, easy to stuff and fits into a fairly small package (smaller than a standard Nalgene bottle). This makes it a great emergency choice for longer trips as well. All together a nice little sleeping bag.
This concludes my test report.
Thank you to both BackPackGearTest and to Montbell for this fantastic opportunity to test the ULAP Thermal Sheet.
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