Kammok Mantis Winter Barrier Review

Kammok Hammock Winter Sock Review

The Kammok Hammock Winter Barrier, an accessory for Kammok’s Mantis and Mantis UL modular hammock systems, is a solid fabric replacement for the zip-off bugnet to be used for increased warmth and weather resistance in cold-weather hammocking. A winter barrier or cover can add a noticeable amount of warmth to a hammock setup, but condensation is frequently experienced with their use. Below, we discuss how Kammok’s Winter Barrier fares in this regard.

Specs at a Glance

  • Dimensions: 90.5 in x 25 in
  • Weight: Manufacturer’s reported weight: 8.5 oz. SectionHiker measured weight: 8.3 oz (not including 0.8 oz for both side wing guylines which need to be transferred from the Mantis UL bugnet)
  • Materials: 15 denier PU/Silicone DWR nylon (Kammok’s Patagium fabric) and no-see-um mesh for the vents.

Color-Coded Setup

The Winter Barrier follows the same color-coding as the Mantis UL’s included bugnet so it’s easy to orient either one correctly when you switch between them. The head end of all the accessories is orange, and the foot end is gray. The zipper sliders share this color scheme so you immediately know where to start each of the four zippers. It’s a simple thing, but you can imagine what a frustrating trial-and-error mess this could be without the color-coding.

The zipper sliders are color coded for easy orientation with the head and foot ends, and they come together in a spot that can be reached while lying down.
The zipper sliders are color-coded for easy orientation with the head and foot ends, and they come together in a spot that can be reached while lying down.

Zipper Function

The Kammok Winter Barrier uses four zippers to connect to the hammock body. Either side can be used as a door for entry/exit or extra ventilation. When zipped shut, the zipper sliders meet closer to the head end than the foot end, so they can easily be reached while lying down. This configuration also means that you always know where the sliders are to be able to find them in the dark. Where the separate zipper ends come together at the head and foot ends, there is a small fabric flap that snaps around the ridgeline to cover the gap.

Side Wings

Like the Mantis UL bugnet, the Winter Barrier has wings on either side of the head end which are guyed out to the same stake as the head end of the tarp. The Winter Barrier doesn’t come with its own guyouts. You need to transfer these from the bugnet when you switch it over. This is simple because they are affixed with small aluminum hooks that clip into webbing loops. For added security, to prevent their loss, you may want to tie them directly onto the Winter Barrier loops.

Guying out these side wings makes the interior of the hammock more spacious. It also creates a flat shelf-like area for some small essentials, with a security pocket that does double duty as a stow pocket for the window/vent covers. However, at the temperatures at which I’d use the Winter Barrier, I’d want most of my small essentials in my insulation–phone, camera, headlamp–to keep the batteries from freezing. While I haven’t had anything fall out of the shelf pockets, I think it’s a good practice to put stuff in the pocket on the side that you are not using as a door.

The winter barrier replaces the Mantis bug net with a solid cover
The winter barrier replaces the Mantis bug net with a solid cover

Because the side wings are guyed out at the head end, it is not possible to fully roll up the Winter Barrier on one side like an open door. Instead, the Winter Barrier has a single toggle on either side of the foot end and matching webbing loops to be able to roll up the foot end of either side and affix it in the open position.

Heat Retention

The Winter Barrier does a great job of trapping heat. You’ll appreciate the coziness it offers on a cold night, like climbing into a fully enclosed tent. There could be a tendency to want to “batten down the hatches” to maximize warmth, like closing the window vent covers or even not guying out the side wings to keep the interior smaller. But doing this introduces considerable condensation into the system.

Condensation Management and Ventilation Features

You put out a lot of water vapor through your breath overnight, and without adequate ventilation, this will condense on the Winter Barrier and get your insulation wet.

The roof vents are held open with a kickstand, affixed with velcro.
The roof vents are held open with a kickstand, affixed with velcro.

The Winter Barrier has kickstand hooded vents that have a small plastic “kickstand” that folds out and affixes with Velcro to hold the vent open. There are two of these small vents in total, one on either side of the ridgeline.

The hooded vents at the roof serve to let warm, moist air escape, but in order to do this effectively, there needs to be the intake of cool, dry air below. This function is served by window vents on the side wings, which are parallel to the ground when the wings are guyed out. The concept is that the combination of these two kinds of vents creates the chimney effect of air movement described above.

I suggest users open both the hooded vents and both window vents fully from the beginning to maximize ventilation. Make sure the kickstand vent is fully situated on the velcro. If they’re closed, you’ll probably experience substantial condensation frozen to the ceiling of the barrier as a layer of frost.

With a nonbreathable fabric, condensation collects on the inside of the Winter Barrier
With a nonbreathable fabric, condensation collects on the inside of the Winter Barrier

If you tend to get up in the night, that’s a good time to check in on your system and see if there are any adjustments you should make. Keep a bandana in the side wings to wipe down the condensation, and open up one of the doors with the toggle for extra airflow. You can do this on the side away from the wind, so the closed side acts as a windbreak and the open side is a massive vent. While this method protects you from wind on one side, the extra ventilation means that the system is no longer trapping heat. Both the roof vents and the side windows are quite small to ventilate sufficiently by themselves and you may still experience condensation with them open.

Non-breathable Fabric

The Winter Barrier is made out of Kammok’s proprietary nylon ripstop, Patagium, with what is described as a PU/Silicone DWR. This is the same fabric used on Kammok’s waterproof tarps, and beyond just a DWR treatment, it feels like the Winter Barrier is a fully-coated fabric. As a test of its breathability, I put a section of the Patagium fabric over my mouth and tried to breathe in and out through it, but I couldn’t.

For maximum ventilation, open one or both doors with the toggle
For maximum ventilation, open one or both doors with the toggle

Usually, a winter cover is made of a breathable fabric, not waterproof fabric. Since we already have the waterproof tarp hung above the hammock, we don’t need full waterproofing, but rather a water-resistant top that will cut the chilling effects of the wind like a windshirt. You wouldn’t want to use the Winter Barrier without a tarp in the winter if there is any chance of precipitation because it wouldn’t shrug off a snow load nearly as effectively as a sharply-peaked A-frame tarp. During my testing, the tarp remained dry. Ideally, a winter barrier would function like a double-walled tent or a tent liner, and move the condensation out. But the non-breathable fabric can’t do this, so moisture condenses on the inside.

Adding an Underquilt Cover

Winter barriers/ top covers don’t prevent the wind from stripping the heat out of your bottom insulation, so it’s a good idea in winter to get an underquilt cover from another vendor (Kammok doesn’t currently offer one) to use in addition to the Winter Barrier. Another alternative is to use a winter barrier (also called a Winter Sock) that provides both top and bottom protection like the Dutchware Winter Sock or the Warbonnet Travel Sock.

Assessment

While I think the Kammok Winter Barrier would benefit from larger mesh panels near the head (and I may modify my Winter Barrier in this way), and/ or larger vents, ultimately, I think the type of fabric is the biggest problem, and if Kammok updates the Winter Barrier, I would suggest switching from a waterproof fabric to a breathable one. I think the Kammock Mantis UL system is fantastic (check out our review here) but I think the Winter Barrier accessory needs a redesign.

Disclosure: Kammock provided SectionHiker.com with a Winter Barrier for this review.

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About the author

Greg Pehrson is an ultralight backpacker who was bitten hard by the MYOG (make-your-own-gear) bug. He repairs, tinkers, and builds gear, often seeking to upcycle throwaway items or repurpose things from outside the backpacking world.

2 comments

  1. My preference for them would be to make a vent with mesh netting rather than vents. Don’t know about you, but I keep seeing mosquitos even when there’s snow on the ground in New Hampshire. In any case, it might be best to future proof the winter barrier against climate-change. Although, given my druthers, I’d far prefer a winter sock that covers the top and bottom of the hammock and underquilt as a single product.

  2. I agree–I used a breathable winter sock over the Kammok Mantis UL last month on an overnight that dipped below 0*F, and it was wonderful. Zero condensation while noticeably retaining heat.

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