The Marmot Phase 30 is a fully hooded mummy bag that is comfortable, more versatile than most fully hooded ultra-light mummies due to its nearly full-length zipper, and is lightweight. While it wasn't the highest scorer in our review, it was pretty close. We chose to recognize it as our Top Pick for Weather Resistance due to its combination of naturally water-resistant Pertex Quantum material, combined with DWR treated 850-fill power down. While this doesn't mean that this bag could get soaked through and still provides the same amount of insulating loft as synthetic material, it does mean that it is better suited than most down bags we tested to handle wetter climates (given that you still take every precaution to keep it dry and air it out whenever possible). While we managed to find a few minor flaws, we think this is a quality ultralight bag that is worth investigating for those worried about water. If water resistance isn't a chief concern for your needs, the warmer Western Mountaineering Summerlite is also worth a look.
Marmot Phase 30 Review
Compare prices at 3 resellers Pros: Warmer than the fully hooded mummies lighter than it, comfortable liner material, roomy footbox, ¾ length zipper
Cons: More suitable for 40F temps than 30, no neck baffle, zipper catches on fabric easily
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Our Analysis and Test Results
In many ways, the Marmot Phase 30 is a similar bag to the Patagonia 850 Down Sleeping Bag 30, except it is lighter and not as warm. Like the Patagonia model, it has an oversized foot box that aids in comfort while sleeping and also features a two-way zipper to help ventilate on warmer nights. Unlike the Patagonia model, it is EN rated, but curiously its comfort rating is a mere 42F, and its limit rating checked out at 33F, so we are not exactly sure why it is called the Phase 30. We found that it wasn't as warm as the Patagonia bag. On the flipside, at only 18.3 ounces, it is over eight ounces lighter than that bag, a very significant weight savings for those who are looking to travel as light as possible.
As we have already mentioned, we chose to award this bag our Top Pick because of its water repelling capabilities. However, many other bags also used treated down in their construction, with the Katabatic Gear Palisade 30 also featuring a similar combination of Pertex shell and hydrophobically treated down. We chose to recognize the Phase 30 instead because it scored higher in our overall ratings, but if water resistance is a primary consideration, check that one out as well.
Perhaps a little disclaimer is in order. While we recognized this bag for its water resistance, we don't want to suggest that this bag is waterproof. In our testing, we found that the Pertex fabric caused condensation to bead up on the surface, but if it was rubbed too much, some would absorb into the face fabric. However, we also found that the capillary wicking action caused it to dry literally within about 30 seconds of airing in the sun in the morning. It was not possible to completely test the claims Marmot has made about their Down Defender treatment, but on an especially dewy night with heavy condensation inside our tent, we suffered from no loss of loft. In short, while the technology in this bag is noteworthy and valuable, the user should still take all precautions to keep their equipment dry for greatest safety.
We have to admit we are a bit bothered by the fact that the Marmot Phase 30 did not exactly live up to its stated temperature rating. Once again, the EN tested comfort rating for this bag was 42F, and the limit rating was 33F, so we don't know where the number "30" is coming from. Regardless, we tested this bag during October nights that went down to about 32F, or freezing, and were a bit chilly, even when wearing long underwear as well. We conclude that it is better to think of this bag as a 40F bag, comparable to the Feathered Friends Flicker 40 UL.
What we liked was that it was a full zip hooded mummy. There is no doubt that being enmeshed in down and fabric like this bag does lead to a much less drafty night than one spent in, say, the Sierra Designs Backcountry Quilt 700, which had a similar score. The zipper has an effective draft tube, and the hood is broad and covers the entire head, leaving only a small hole for the face. These features add to the warmth and make it a decent choice for three-season use, even if it is a bit on the thin side. For those who wish to use this bag during colder nights than we did, laying clothing inside will be a must.
On our independent scale, our regular sized bag registered 18.3 ounces, with another 0.9 ounces for the included stuff sack. This was a bit heavier than advertised on Marmot's website, but still light enough for long distance adventures.
We also thought this bag stuffed down pretty small in the included sack, so it won't take up extra room in your pack. It was virtually the same weight as the Enlightened Equipment Revelation 20, and while it didn't offer as much insulation as that quilt, it also gave us a hood and full enclosure. While it was a tad bit heavier than the Western Mountaineering Highlite, we thought it was a much warmer and better fitting bag.
For testing, we ordered a regular size Phase 30 (it also comes in long), and while it wasn't stated anywhere on Marmot's website, this bag is designed for people up to 6'0" tall. Our head tester is 5'11", and thought that this bag was of perfectly adequate length. It also features an anatomically constructed foot box, much like the one found on the Patagonia 850, giving the feet the room they need to be natural while enclosed. We certainly enjoyed this feature but found the amount of space in the legs and lower torso to be a bit tight, especially when wearing extra clothes.
Other features contributed positively to this bag's level of comfort. The Pertex 10d fabric used for both the face and inside liner is soft and slippery to the touch, and we found it to be very comfortable for sleeping in, with little friction between the liner and the clothes we were wearing. We also thought that the hood fit well, was very cozy, and we were happy that the drawcord easily rested outside of the bag, so it didn't hit us in the face as we slept.
There is no doubt that versatility is the Phase 30's strongest suit, although it didn't register as high as most of the quilts that we tested, like the Sierra Designs Backcountry Quilt 700. While it wasn't the warmest bag available, the fact that it can be fully enclosed and zipped, with a warm hood, made it a good choice for stretching your thru-hike deep into autumn. Likewise, the fact that it offers nearly a full zip, in stark contrast to the Patagonia 850, meant that it was far easier to ventilate than nearly any other ultra-light mummy bag.
What set it apart was the reason that we awarded it our Top Pick, the fact that it features both a superior water-resistant Pertex Quantum nylon face and liner fabric, and combines it with treated down on the inside.
Although you must still be careful to keep it as dry as possible, we think this bag makes a decent choice for those tackling the PCT, who might be concerned about the rain they will inevitably encounter once they hit Oregon and Washington, or the AT, who could encounter deluges almost anywhere. There is no doubt this is a bag suitable for epic thru-hikes.
The Phase 30 has an interesting combination of unique features that we didn't find on any other ultra-light bag, combined with some widespread features that didn't perform as well as we would have liked. Its unique offerings included a small internal pocket with a zipper just big enough for a small smartphone (our older iPhone 5 barely fit). Its position is on the side of the chest, so you don't risk rolling over and smashing whatever you put in there. We thought it was nice for a cell phone to keep the battery alive on cold nights, but wouldn't think of using it for our glasses, just in case we did roll over. It also has a glow-in-the-dark pull tab on the zipper so you can quickly find it once the headlamp has been shut off, but was also dim enough so as not to be distracting from our zzz's.
While these features are nice, we would have liked to see the standard features perform a bit better. In particular, we found that the zipper, which is a tiny gauge to save weight, has the habit of catching on fabric two or three times per night. While there is a more durable zipper guard fabric in place, it wasn't nearly as large a strip as we found on the Flicker 40 UL, and not as effective either.
We were also missing a neck baffle, although we were able to tighten up the facial opening till it was a tiny hole, and barely allowed in any air. With performance roughly in line with the Katabatic Gear Palisade 30, it scored about average in this metric.
The Marmot Phase 30 is a lightweight hooded mummy bag that is not as warm as its advertised temperature. While you can stretch its use into three seasons with success, as we did, it will be most comfortable in the summer, especially if you plan to use it at higher altitudes. Its unique features mean it's a good down insulation choice for wetter weather. As a great all-around ultra-light bag, we could see this serving people well on thru-hikes.
This bag retails for $400. This puts in barely on the higher side of average, in line with the cost of the Patagonia 850 as well as the Zpacks Classic. Since it scores pretty comparable to these bags in our overall rankings and was worthy of recognition as a top pick, we think this presents a pretty good value.
The Marmot Phase 30 offers all the great advantages of an ultra-light sleeping bag, such as super lightweight and great packability, while also suffering from their common drawbacks — not super warm, fairly expensive. We love its versatility and think it is a great choice for those who want an ultralight mummy bag rather than a quilt, but don't want to pay the price in ounces.
— Andy Wellman