Introduction
The Macpac Epic 150 SF sleeping bag has a lightweight Pertex Endurance shell and is fully seam taped. It is functionally a bivy sack and sleeping bag combined. Think of it as an insulated bivy sack. I did some controlled experiments, and also tested it stargazing in a damp meadow and sleeping under a minimal poncho-tarp on a stormy night. So, how waterproof is it?
What’s Good
- Pertex Endurance outer shell is waterproof under normal use conditions
- Allows you to leave the bivy sack at home
- Shoulder and hip girth allow room for wearing clothing inside
- Hood drawcord works smoothly
- Very durable
What’s Not So Good
- Shell fabric transmits water under moderate hydrostatic pressure
- Zipperless design may not provide enough ventilation on warmer nights
- 75% of the bag’s weight is fabric, 25% is down
- Inner shell fabric is not completely down-proof
- Available in only one size
Specifications
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  Manufacturer
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Macpac (New Zealand) |
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  Year/Model
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2005 Epic 150 SF |
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  Style
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Hooded, waterproof, zipperless mummy bag |
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  Fill
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750-fill (US Standard) goose down, 5 oz (150 g) of down |
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  Loft
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Measured loft is 2.25 in (6 cm) double layer; manufacturer claimed loft is 2.5 in (6 cm) |
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  Manufacturer Claimed Temperature Rating
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54 °F (12 °C) |
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  Weight
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Measured weight 20 oz (567 g); manufacturer’s specification 19 oz (540 g); weights include sewn-in stuff sack (0.6 oz / 17 g) |
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  Sizes
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One size (Standard); length 79 in, shoulder girth 61.4 in, foot girth 42 in (200 x 78 x 53 cm), fits a person up to 73 in (185 cm) tall |
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  Fabrics
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Shell is 30d (2 oz/yd2, 68 g/m2) Pertex Endurance (hydrostatic head pressure 1500 mm/2.1 psi, moisture vapor transmission rate 9000 g/m2/24 h); lining is 30d VapourLite ripstop nylon taffeta with DWR.
Note: the 2006 model will have a Reflex LoftPro outer shell (a proprietary PU laminate with nylon face), 2.2 oz/yd2 (63 g/m2), hydrostatic head pressure 10,000 mm/14.2 psi, moisture vapor transpiration rate 15,000 g/m2/24hours |
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  Features
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Pertex Endurance outer shell, all seams taped, non-baffled construction, drawcord hood, hang loop, attached waterproof stuff sack |
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  MSRP
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$280 USD |
A Note on Pertex Endurance
Pertex Endurance is 30-denier ripstop nylon with a highly water-resistant outer coating. It allows moisture to pass freely from the inside, which makes it ideal for a sleeping bag shell fabric because there is minimal moisture trapped inside the bag. Several sleeping bag manufacturers use it as an outer shell fabric because of its exceptional water resistance, but actual waterproofness depends on whether the seams are sealed and how much hydrostatic pressure is placed on the fabric. Endurance will withstand a hydrostatic head pressure of 1500 mm (about 2 psi) before leakage occurs, which is not very high. In comparison, most polyurethane coated tent floors have a rating of 5000 mm or higher. A person side sleeping in an Endurance-shelled sleeping bag would come very close to exerting a 2-psi downward force, especially at the hips, so water under the fabric could potentially come through under pressure.
Performance
My first impression upon receiving this bag for review was “this bag is 75% fabric and only 25% down”! However, if you consider the utility of its Pertex Endurance shell and do the math and testing, you’ll see the Macpac Epic 150 SF in a different light. This bag is targeted to the adventure sports niche, where the intended use is minimalism – grabbing some sleep under the stars and getting back on the trail. For us ultralight and super-ultralight backpacker types, it means we can leave the bivy sack at home, because the Epic bag is functionally a bivy sack and sleeping bag combined. (For clarification, the Macpac Epic sleeping bag only uses the name “Epic;” it does not use the water-repellent Epic fabric by Nextec.)
If you sleep under the stars or use a poncho-tarp or ultralight tarp for shelter, chances are you also take an ultralight bivy to protect your sleeping bag from dew or spindrift. Alternatively, if you use a waterproof sleeping bag you can leave the bivy at home, saving 6 ounces or more. The trade-off is that the Pertex Endurance shell material, at 2 oz/yd², is twice as heavy as Pertex Quantum (0.9 oz/yd²) used on many ultralight bags, and adds about 3.5 ounces to the weight of the bag. The extra weight is partly offset by the bag’s zipperless design.
Macpac uses a proprietary Stitch-Free construction technology to attach the bag’s outer shell to its inner lining, which avoids stitching through the Endurance shell and seals the sewn seams in the lining. It also creates chambers to control the down, which is equivalent to sewn-through construction (no baffles). This unique seam taping technology preserves the integrity of the prized Pertex Endurance shell, eliminating the possibility of leakage through stitched seams. The VapourLite lining has a DWR finish, which causes water to bead up on the surface, but it is not waterproof.
The outer shell (left) on the Macpac Epic 150 SF is Pertex Endurance seam-taped to the VapourLite lining (ripstop nylon taffeta with DWR). There is no stitching through the outer shell. The hood (right) operates smoothly to cover your face and provide a breathing hole.
When a manufacturer claims that their sleeping bag is waterproof, it better be, because you are counting on it to keep your butt dry and warm. This is even more important for a down bag, which loses its loft when wet and can be difficult to dry in the field. I took Macpac’s claim as a challenge and put it to the test. Since leakage will most likely occur when a fabric is under pressure, I set up a simple experiment to simulate sleeping in a puddle of water all night. I poured two cups of water on a tray, laid the hip area of the sleeping bag on the tray, put two 5-pound weights on top of the bag, then poured 2 cups of water around the weights and let it stand for 8 hours.
Was the bag truly waterproof? Well, almost. There was no leakage at 4 hours, but after 8 hours one seam on the top side leaked enough to produce some noticeable wetting on the inside. I weighed the bag and found that it had gained 0.35 ounce of water. There was no evidence of leakage on the bottom side. I turned the bag inside out and it dried out quickly.
The amount of leakage was minimal, and only occurred on the top side. In a normal situation I would expect leakage to occur from below, where pressure from my weight caused the leakage, not from above. It was time to scrap weights and put myself in the puddle of water under real sleeping conditions.
In my first waterproofness test (left) I placed the hip area of the sleeping bag over a tray of water, placed two 5-pound weights on top, and poured water around the weights. After 8 hours a small amount of water leaked through the top side and was visible on the inside (right).
I did a second test with me in the bag to determine whether leakage would occur under simulated field conditions and whether it is actually a problem. I placed an open-cell foam pad (which acted like a sponge) in a tray of water, arranged Therm-a-Rest pads on both ends of the tray, and slept in the bag with my hip area on the wet foam pad.
The result was similar to the first test, only this time the water came through from the bottom and was enough to dampen my microfleece pants and underwear. Again, it took about 4 hours for the leakage to be detectable. I stopped the experiment after 6 hours, when my butt felt thoroughly wet. I weighed the bag and clothing before and after drying and found that 0.88 ounce of water passed through. Although the actual amount of water passing through was not high, it was enough to thoroughly wet the compressed area and cause discomfort. Conclusion: concentrated body weight (such as the hips) provides enough pressure to move water through the sleeping bag’s Pertex Endurance shell, and the amount of water transmitted is enough to collapse the down and chill your tail.
My second waterproofness test (top) simulated worst-case field conditions. I slept overnight with the hip area of the sleeping bag on top of an open-cell foam pad in a tray of water. The water started leaking through after about 4 hours, and after 6 hours (bottom) both the bottom of the sleeping bag and my butt was thoroughly wet.
The “lab” tests I performed simulated a worst case scenario – sleeping in a puddle of water, so how does that translate to using the sleeping bag in the field? On backpacking trips I slept in the Macpac Epic 150 SF under the stars in an open meadow and under a poncho-tarp on a rainy night. Under Southern Rocky Mountain conditions I had to wear a down jacket and pants inside the bag (which the bag’s girth easily accommodated) to stay warm, but the real issue was whether or not the bag would stay dry inside.
When I slept under the stars there was heavy dew on the bag surface in the morning, but shedding surface moisture was no problem for the Pertex Endurance shell because it was not under pressure. The fabric’s hydrophobic surface shed heavy dew literally like a duck’s back.
Sleeping under a poncho-tarp on a rainy night was basically a similar situation. Some spindrift come in under the poncho-tarp, even with mild wind gusts, and the humidity was very high, but there was not enough moisture to create a puddle of water. The sleeping pad elevated the Macpac Epic 150 SF off the ground, adding further protection from any water that might run in. The bag stayed dry inside in spite of whatever moisture my body gave off and the Macpac being quite damp on the outside. On another occasion I slept in the bag in a single wall tent during an overnight deluge (2 inches of rain overnight); conditions that produced a lot of condensation inside the tent and dampened gear. An ordinary down bag would get pretty damp and lose loft under these conditions, but the Macpac Epic didn’t gain a gram. Conclusion: the Pertex Endurance shell is effectively waterproof; it readily sheds surface moisture, and water does not come through the shell as long as it does not exceed 2 psi of pressure. Avoid sleeping directly on wet ground, in a puddle of water, or with water between your sleeping pad and bag.
The functionally waterproof Macpac Epic 150 SF sleeping bag provides an extra measure of dry butt insurance while sleeping under a minimalist spinnaker poncho tarp.
I slept in the bag under a variety of conditions and did not detect any clamminess inside from trapped perspiration. The Endurance fabric breathes very well and readily passes moisture from the inside out.
The Epic 150 SF contains 150 grams (5 ounces) of 750 fill-power goose down. As I mentioned, only 25% of the bag’s weight is down, but that may be enough. With a comfortable temperature rating of 54 °F, this bag is suitable for summertime backpacking in many locations. For me, it was a little light for summer backpacking in the Southern Rocky Mountains, where nighttime temperatures can drop a lot lower. By wearing my hiking and camp clothes inside the bag, I was able to stay warm down to about 40 °F.
Although it’s obvious that this bag is too light for mountain backpacking, that’s not really an issue. Instead of the Epic 150 SF, one can get the 300 SF with 300 grams (10.6 ounces) of down, or the 450 SF with 450 grams (16 ounces) of down. With baffled construction and half-length water-resistant zipper, the 300 SF would be a better choice for summertime backpacking in the mountains, and the 450 SF would be a good choice for spring/fall backpacking and sleeping in a snow cave or igloo.
Comparing the Macpac Epic 300 SF (with its Pertex Endurance shell) with the popular Marmot Hydrogen bag (with its Pertex Quantum shell), the Macpac bag comes out approximately 3.7 ounces heavier. Both bags have approximately the same amount of down, baffled construction, and a half zipper, so the weight difference is mostly due to the Pertex Endurance shell and slightly heavier lining material in the Macpac bag (30 denier versus 20 denier). The total weight of a waterproof/breathable bivy plus the Marmot Hydrogen easily exceeds that of the all-in-one Macpac Epic bag.
I did not find the zipperless design to be a problem for mountain backpacking, where the issue is getting enough warmth out of a bag. However, ventilation is likely to be an issue in warmer, more humid climates. One annoyance was that the bag’s nylon taffeta lining is not completely downproof, so there were always a few feathers coming through each time I examined it.
The Macpac Epic 150 SF VapourLite lining is not completely downproof.
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. Click here for the complete Backpacking Light Position Statement on Sleeping Bag Temperature Ratings.
At $280 the Macpac Epic 150 SF is a bit pricey. The seam taped Pertex Endurance shell apparently accounts for about half of the bag’s price tag. Performance doesn’t come cheap! However purchasing a comparable sleeping bag and lightweight bivy sack separately does add up to more cost and weight.
As of this writing (December 2005), the future of Perseverance Mills and production of their Pertex Endurance fabric is uncertain. If and when the supply of Endurance runs out, Macpac plans to use their proprietary Reflex LoftPro shell fabric (a polyurethane laminate, see specifications at the top of this review) on their Epic series of sleeping bags. This fabric is slightly heavier, and I predict it will be more waterproof but less breathable than Pertex Endurance when used as a sleeping bag shell.
What’s Unique
The Macpac Epic 150 SF is a functionally waterproof sleeping bag, which gives it extra utility and saves weight for adventure racing or ultralight backpacking. It’s essentially an insulated waterproof/breathable bivy sack.
Recommendations for Improvement
I suggest that the bag’s waterproof stuff sack not be attached to the bag. Many people stuff their sleeping bag into the bottom of their pack, which eliminates the stuff sack to save a little weight and avoids over compressing the down.
The Macpac catalog shows this bag having a “two part multi-adjust closure.” My test sample had one simple drawcord, which worked fine. The two part closure sounds like overkill and would add weight.
