Home / Gear Reviews / Backpack Reviews / Granite Gear eVent Uberlight Cuben Fiber Dry Sacks

Granite Gear eVent Uberlight Cuben Fiber Dry Sacks

manufactured by :
Philip Werner
Version:
1
Price:
41.95

Reviewed by:
Rating:
5
On September 14, 2015
Last modified:September 27, 2016

Summary:

Granite Gear makes excellent waterproof roll-top cuben fiber dry sacks. Called eVent Uberlight CTF3 Dry Sacks, these cuben fiber stuff sacks have the added advantage of a breathable eVent air purging panel on the bottom which allows air to escape when the sack is compressed.

Cuben fiber stuff sacks from Zpacks.com (left) and Granite Gear (right)
Cuben fiber stuff sacks from Zpacks.com (left), Granite Gear (center and right), and Hyperlite Mountain Gear (covered)

If you thought that the only place to buy ultralight cuben fiber stuff sacks is from cottage gear manufacturers, you’d be wrong. Granite Gear makes excellent waterproof roll-top cuben fiber dry sacks. Called eVent Uberlight CTF3 Dry Sacks, these cuben fiber stuff sacks have the added advantage of a breathable eVent air purging panel on the bottom which allows air to escape when the sack is compressed.

Granite Gear’s eVent CTF3 Uberlight Dry Sacks are available in four sizes:

The beauty of using cuben fiber stuff sacks and dry sacks is that they weigh almost nothing and can help you keep your gear dry and organized inside your pack. As a point of comparison, a Sea-to-Summit 8 Liter silnylon waterproof dry sack weighs 1.1 ounces, or about twice as much as the same volume in cuben fiber.

Construction

Granite Gear’s eVent Uberlight Cuben Fiber Dry Sacks are taped rather than sewn, which is what you want for waterproof cuben fiber dry sacks (the stiff roll top rand is sewn and taped – but it has to be for strength.)

All of the sample bags I received from Granite Gear were green, although other colors are available (orange, blue, and yellow). This is handy if you like to color code your pack’s contents. The green stuff sacks are also nearly transparent, allowing you to identify their contents, which I consider a very nice feature.

Granite Gear includes several transparent repair patches with each dry sack since cuben fiber is susceptible to puncture, although you have to go out of your way to do so. The fabric is very resistant to tearing however, unless you try to overstuff a stuff sack with contents that are way to big for the bag size. However, when that happens you’re much more likely to blow out the seam rather than rip the fabric, but this is true of any dry sack, regardless of the material it’s made with.

The white eVent air purging panel at the bottom of all Granite Gear eVent Uberlight cuben fiber stuff sacks.
The white eVent air purging panel at the bottom of all Granite Gear eVent Uberlight cuben fiber stuff sacks.

Air Purging Panel

The air purging panel on Granite Gear’s eVent Uberlight cuben fiber dry sacks lets you squeeze out any remaining air inside the sack after you roll the top closed.  While you can see the air bubbling out of the bottom if you hold the dry sack in a pool of water and squeeze, there are times when the rate of purging is imperceptibly slow. This occurs when the contents inside limit the flow. For example, if the cover of your sleeping bag or quilt covers the inside surface of the air purge panel, the rate of air flow is slowed markedly. Air is still being purged, but you’ll have to sustain pressure on the bag much longer to see the shrinkage occur.

However once extra air is purged, it will flow back into the dry sack unless you roll the dry sack top tighter or push the sack into a tight space in your pack where the contents will stay tightly compressed. I found this counter intuitive and expected the eVent Uberlight air purge mechanism to work like the airplane travel compression sacks that you can get from Eagle Creek, that permanently exclude air when compressed.

When contacted, Granite Gear confirmed that air can flow back into the eVent Uberlight cuben stuff sacks even after it’s been purged. “It is normal for air to come back into a Uberlight sack. The material at the bottom, eVent, has pores sized so that air molecules can pass through it, but water molecules, which are much larger, cannot. In terms of the migration of air molecules, it is not a one way deal—air will pass through the material to equalize inside and outside pressure as needed. All waterproof-breathable membranes are like this. In using the sack, you should use the roll down top to compress the contents and expect there to be a small amount of rebound afterward.”

MfgLitersWeight (oz)Weigh (g)Price (USD)
Granite Gear70.5315$41.95
Granite Gear100.617$44.95
Granite Gear130.6719$49.95
Granite Gear180.7421$52.95
Zpacks.com5.60.8524$22.95
Zpacks.com9.50.9527$25.95
Zpacks.com12.31.131$28.95
Zpacks.com441.954$39.95
MLD60.616$22.00
MLD121.234$27.00
MLD251.750$39.00
HMG3.70.822$35.00
HMG9.41.234$42.00
HMG19.51.645$55.00
HMG441.851$70.00

I guess I don’t understand the added practical value of having stuff sacks that refill with air after you’ve compressed them, especially given the premium price that Granite Gear charges for the Uberlight stuff sacks, compared to prices from other cuben fiber dry sack manufacturers like Zpacks, Hyperlite Mountain Gear, and Mountain Laurel Designs.

While I can get most of the extra air out of a dry sack by pressing down on it with my arms or a knee, I’d be willing to be more for dry sacks that purge the air permanently, like Eagle Creek’s travel compression sacks. But I’m not willing to pay a premium for dry sacks where the air flows back in. That doesn’t make any sense.

I’d give the Granite Gear eVent Uberlight cuben fiber dry sacks a pass unless you get them at a huge discount or can’t buy gear from other cuben fiber dry sack manufacturers because of the added expense of custom’s taxes or off shore shipping. The eVent Uberlights are still perfectly good cuben fiber dry sacks, but not at a premium price.

Disclosure: Granite Gear provided Philip Werner (SectionHiker.com) with the sample eVent Uberlight stuff sacks reviewed in this article. This post contains affiliate links. 
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25 comments

  1. I’ve owned a few Granite Gear eVent cuben drybags and they’re certainly beautifully made but really not tough enough even for normal ultralight use. The main weakness isn’t the cuben but the eVent base which pretty quickly gets abraded so micro and not so micro holes appear. It’s a shame as they’d be great if they just got rid of the eVent and made it all cuben.

    I’ve not tried the MLD or HMG drybags but can testify to the quality of the Zpacks though I think the Granite Gear are more intrinsically waterproof when new due to their method of construction as I’ve never seen any problems in the interface between the cuben and eVent or in the cuben itself.

    • Good to know. I haven’t experienced micro holes yet, but I have seen some abrasion where the outer fabric over the eVent bottom wears away. I’ve written it off as normal wear and tear.

      Hyperlight Mountain Gear makes excellent cuben fiber dry sacks but they are priced at a premium as well, compared to Zpacks and MLD. The HMG sacks are made with heavier cuben fiber so less prone to the abrasion that you get with scrunching cubic a million times. I’ve been really impressed with their quality this year. Review in the pipeline…

      But I completely agree with you. Granite Gear should just make plain CF dry sacks and lose the eVent bottom. It’s a non-feature.

      • I’ve been using the GG eVac dry sacks for a few years and I’ve had no problem at all with the eVent fabric getting holes. I use a normal level of care when packing up, but I don’t baby them.

        They’ve performed so well, I’m going to make the leap and give the cuben fiber version a try.

      • I doubt you’re actually looking at the eVent layer. Waterproof breathable laminates are usually very thin and covered by an outer fabric so they don’t abrade off.

      • Cindy are you sure your eVac Dry Sacks are made by Granite Gear as Sea To Summit make an identically named item and I don’t see that GG does. The STS eVac is much more rugged than the GG eVent / cuben item described above as the eVent is covered in a protective layer and therefore not prone to the issues I outlined.

      • Liam, you are absolutely correct! The eVac Dry Sacks are made you Sea to Summit. I also use GG airbags (no eVent panel) which I also love, and got the manufactures mixed up. Thanks!

  2. I do like the idea of having different colors for organization. Everything in my pack goes in a stuff sack and sometimes it can take a minute to figure out which oblong gray blob is what.

  3. I’ll be interested to see the HMG review. I’ve largely moved away from cuben dry bags (though love my Zpacks cuben stuff sacks) and use a Sea To Summit Ultra-Sil Nano Dry Sack for my clothes bag and the Sea To Summit Ultra-Sil eVent Compression Dry Sack for my sleeping bag. Especially as STS is obviously easier and quicker to source and cheaper down here in Australia although within reason budget isn’t a factor.

    I do think the 12.3 litre Zpacks dry bag for use as a food bag is probably (in my mind) the gold standard for that role.

    • Yeah, I’ve got one kicking around here somewhere. :-) Very good use of cuben, although I pretty much just use an Ursack all the time now to avoid hanging anything. Much easier in the dark. :-)

  4. Philip, Thanks for another great review. I have about 200 trail miles on this granite 19 L CF bag and have had no failures. The eVent is feeling softer and if it shows any wear I’ll cover it with the 3M CF tape.
    The GG sits aside my DIY cuben/poly hybrid bear bag (Source = Zpacks) and two DIY .51 CF bags in my pack. The 19 L is also a nice size for a pillow. I wouldn’t use these for bear bags unless you use a bandana or something as the attachment point to the line/cable. That being said, my son used a .51 CF bear bag as a ranger at Philmont in 2014 (1k miles) and the same one on the el Camino Santiago (500 miles) and broke it out during our recent GSMNP through hike last month. HIs trick to making it last was to tape an external attachment point for the bear line. The 19 L GG is without stitching with the exception of the neck/clips. All of my DIYs are taped (without stitching) with the exception of the bear bag which could have 13lbs of food and cooking gear and smellable stuff in it at a time. The bear bag is sewn and taped. It has a round flat bottom which makes it free standing. The bear bag also doubles as a huge bucket (great for a good trail bath and foot soaking).
    The transparency of CF is also very handy.
    Concerning color coding, magic markers work on CF.
    Concerning price, DIY is really the way to go with CF bags. 1 Yard and tape is about $40. A lot of the source sites, however, are out of stock at the moment.

  5. FYI – Water molecules are actually smaller than air molecules. Air is mostly N2 (28 g/mol) and O2 (32 g/mol) whereas water molecules are substantially smaller (18 g/mol). Sorry I can’t give you a good explanation as to why air passes through and water doesn’t. That explanation doesn’t make sense anyway since being a supposedly WPB fabric, it is supposed to let water escape. Otherwise they wouldn’t use it to make WPB shells. More likely the answer is that it allows molecules to pass in the gas phase (air and water vapor) but not in the liquid phase (liquid water). This would make it waterproof but breathable. Still not a molecular explanation however.

    • Molecular weight does not equal size. A water molecule is approximately 2.75 Angstroms in diameter while nitrogen and oxygen are about half that size 1.55 Angstroms. So, while it is possible to build a molecular sieve to separate these molecules, I still suspect you are correct. Most likely the material takes advantage of the intermolecular properties (cohesion, surface tension) of liquid water to keep it water proof yet still allow air to be purged.

  6. I thought your recommendation to pass on the Granite Gear CF stuff sacks was right on. I have used the Zpack CF bags which I though were expensive until I looked up the prices on the Granite Gear Bags – I use the 2-Medium (5.7L.) for which I paid $22.95 – The closest GG was nearly twice as much and included an air-valve, that seems to fail after awhile – if I can believe the comments I read. Thanks for including price in your recommendations.

  7. Yama Mountain Gear offers DIY cuben stuff sack kits for $35 plus shipping. Probably worth checking it out if you are in the market for cuben stuff sacks.

    • I used their kit to make a bunch of CF stuff sacks and it is a very good deal. Plus it is a fun way to spend an afternoon. They are draw string so not water proof but great for things you don’t mind getting wet.

  8. The air returns to the bag slowly enough that once you compress it you can slide it into your pack before it uncompresses. I’ve found that mine continue to compress even further as I’m hiking and my pack continues to settle. When I arrive at my destination they’re all nice and flat, and as I pull them out they slowly come back to size. I’m a fan of the e-vent patches.

  9. Why does anyone need a stuff sack made of a fabric that allows water molecules to evaporate from the inside to the outside? It can never work as well as eVent jacket because there is no body heat to create evaporation.

    My goodness….a vapor liner, leaving a zipper open for cooler sleeping, setting the bag out in a breeze or the sun while you cook, or letting part of hang out of your pack sounds like much more practical way to get the bag drier.

    • It’s not for drying wet gear, but for evacuating air so you can shrink the stuff sack smaller.

      • The eVent panel on the bottom of the Granite Gear CF roll top stuff sacks allows it to function as a compression sack; ideal for puffy items like sleeping bags and down jackets. Without the eVent panel, air gets trapped and can not be removed once the rolled top is sealed. With the eVent, you can further compress your gear by completing a few more rolls before fastening the buckle. Just stow it in your pack immediately before any air is drawn back in.

  10. Other than weight and waterproofness…why not use the Eagle Creek stuff? They seem to be the only air evacuation bags that actually keep air out?

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