Why You Should Spend a Few Ounces of Pack Weight on Rainwear Ventilation Features

How do these jackets vent when your backpack waist belt, shoulder straps, and sternum strap are worn over the jacket pressing it against your body? (reference to The Packa).

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Edward – Welcome to BPL!  I love the Packa for all of the reasons Ryan explains in his article.  With that said, something that weighed 6 ounces would be nicer than the 16 ounces that my custom Packa weighs, but I justify it with the following:

• I’m REALLY happy with my custom Packa and feel that’s worth a couple of ounces
• Because of the pack cover I don’t need to worry about pack liners or dry bags, saving some weight
• I generate a lot of heat when hiking and the huge pit zips help keep me ventilated
• In intermittent showers it’s easy to go from “rain mode” to “pack cover mode” (and back) while I’m hiking – the other guys are taking off their packs, digging out their rain jacket, putting on the jacket, and then finally donning their pack again.  Then the rain stops and they reverse the process to keep from overheating.  If it looks like it’s going to rain the day I’m hiking I just put it on as a pack cover and it couldn’t be more convenient if I need to pull it on myself during the day.
• I never have to worry about my shoulder straps rubbing the DWR finish off my expensive rain jacket because the Packa goes over the straps
• My pack stays dry even in torrential downpours.  One of my buddies, wearing a traditional rain jacket and with a pack cover on his pack, was surprised that his sleeping bag got wet from water running down between his jacket back and his pack – this can’t happen with a Packa.

Regular readers are probably annoyed with my constant “Packa Praise”, but it is one of the most useful pieces of gear I carry.

I’ve used the Packa and it’s a much better option than a poncho, but its use case is limited to when temperatures are not too warm or too cold, the wind is not too breezy, you’re mostly hiking on trail, and don’t need to see your feet, no bushwhacking or scrambling, and you don’t need to wear it by itself without a pack. It’s also kind of heavy when/if it has to stay in your pack. It’s a pretty specialized piece of equipment that doesn’t extend too far beyond trail hiking in temperate conditions below the treeline (in general, of course, I’m sure Packa fans will be happy to point out exceptions).

The Packa will nail that use case for many hikers, I’m sure, but it’s not versatile enough for the type of hiking I want to do, and I’d really like to own and maintain fewer jackets.

I personally like my Arc’teryx Zeta FL jacket and Pants. They keep me dry in rain and snow, they block wind when needed and when not needed, they weigh very little and disappear in my pack. The jacket does not have pit zips, but I am ok with that. I love the side zipper on the pants legs.. Very convenient for putting on or removing without taking my shoes/boots off. I also like that if needed, I can use them at night as part of my sleep system.. Top and bottom, just top or just bottom.  I have found at times it works well with my bivy.

Re: Zeta fl jacket: $350.00 for an “emergency” rain jacket? and the site keeps reiterating the word “emergency” in their description. This doesn’t inspire confidence in me.

@jscott yeah, Arc’teryx is a little funny that way, aren’t they? The reality is that it’s a 20D nylon fabric laminated to Goretex Paclite Plus, which many in our community would call “overbuilt”. So if that’s an “emergency” jacket what would they call the 7D fabrics from Enlightened Equipment, ZPacks, or Montane? 😂

You can get it on sale..  Like now.. $262, lol.  It works. Expensive yes, really!! I have been through 2 or 3 different rain/snow jackets/pants and they never quit worked out well for me . So I finally invested in the Arc’teryx and have not looked back. Yes I grabbed them on a discount too.  They get plenty of use from me. I walk 2 miles every morning and again in the afternoon Monday thru Friday to and from work..Year round.  Rain, Snow, Wind, Cold.. the jacket is in my pack and gets put on whenever needed. The pants I will use if its heavy snow fall and cold out. Obviously I pack them on my backpacking trips also, not always the pants.. Depends on the season and weather. Again,  it’s one of those things I have no regrets buying and would not hesitate to buy again if needed,  and judging by the quality of them I do not think I will need to be buying again for a very long time!  Not sure why the say emergency..  But I guess if you are hiking through the mountains and a storm hits, that could represent an emergency situation?  I know for myself, last winter we camped on Hunter Mt in the Catskills and I was using my hammock with Cuben Fiber tarp. A nasty snow storm hit us and dumped about 8- 10 inches of snow..and ferocious winds!! Well before the evening rolled into darkness, the wind shredded my tarp to pieces.. thankfully I carried my Snowyside eVent bivy and also we were camped near a lean to.. I am also thankful that I had those pants and jacket!! I hiked in them during the day and I used them for extra protection during the night in my bivy while getting blasted and pounded with heavy snow and intense winds all through the night.  I lost all faith in DCF shelters and tarps after that night and can not justify that expense at all… the minimal weight savings and extreme cost and packability??? But that’s for another thread!  So I understand the gag reflex looking at the price tag, but I can totally justify it for myself personally.

It appears that the Zeta FL is discontinued.  They seem to be available only at the Arcteryx Outlet.  The replacement is the Zeta LT.  40 denier Paclite+.  3.7 ounces more.  It will have less MVTR than the FL.  They did add hem and cuff adjustments.  No pit zips.  Of course, who needs pit zips for the Emergency Use described by Arcteryx.  Arcteryx seems to be reshuffling their jacket lines and names.  Could be something like the FL somewhere, but I have not found it.

I was using an old OR Rampart which was a 70D PU coated jackets that had torso zips, two way zippers and mesh backed pockets but it finally died to delamination.  I picked up a few year old OR Guardian jacket that has similar features and only 50D but has the Ascentshell tech that is supposed to be great MTVR.  Haven’t got it out in a full day downpour yet but trying.  Weird thing is that both weigh about half an ounce of each other.

I think I am going to buy an Anti Gravity gear UL jacket that is 70D siliconized on both sides and that has a two way zipper and 17″ pit zips to try out.  I don’t push myself too much so even if it does not work for hiking I can use it for around town for 7.6oz.  I know people think it is a ventilated trash bag but that is how I feel in most rain jackets.  And the weight is good and has some durabilty which alot of the jackets mentioned did not.

With a two way zipper, I say heck with the pit zips which just add more weight and sometimes leak.

Hiking the Southwest then the West in seasons where rain isn’t constant has spoiled me into taking ultralight shells.  My current one is the Montane 777, though I’ve been thinking about that Rab Phantom for longer summer hikes .. less zipper to snag and an ounce of weight savings.

That said, I had to retreat from a northern Oregon and southern Washington state trip last week or so, as it looked too cold and wet despite switching to a synthetic puffy.

If needing to extend hiking into the cold and wet while exercising (hiking), I can definitely see pit zips helping under a bigger pack.  Wonder if more backpackers start going into colder weather to avoid drought and wildfires (2022 looks like another hot one), if manufacturers would come up with alternative designs?

Nice call about the zips going further up the leg.  Didn’t consider that. When it gets colder I usually switch to mountain biking anymore, but maybe a weekend or weeklong backpacking trip is in the cards

From rainy western Washington:  I hesitate when I see a fabric is DWR treated; I doubt the DWR will be water repellent for very long.  I’ve been using a Columbia Outdry rain shell especially in cold, windy and rainy weather from the 30’s to 40’s.  The Outdry’s shell feels a bit like rubber; it feels like it would insulate better against the cold rain.  The wet rain on the outside of a rain jacket sucks heat out of your interior layers, as well as lowering the inner surface of the rain jacket to below the dew point, hence condensation and wetting out.  Compared to nylon fabrics, the Outdry seems less conductive, therefore warmer.  The Outdry is 100% waterproof, which is the only thing I’m interested in, for a rain shell.  Rain does not get “semi-absorbed” into the fabric, as is so common with others (except for DCF fabric).   Pit zips and pocket zips and the front zip offer ventilation. It weighs 13.40 oz.   Has anyone else tried using the Columbia Outdry Extreme?

I prefer other highly-ventilated rain gear, without a big weight penalty, backpacking mostly in the rainy parts of coastal California.

For showery forecasts, my old Golite Chrome Dome umbrella over a DWR-treated windshirt and windpants works great. Almost too much ventilation, quickly learned to point the umbrella into the wind. Easy to stow and retrieve between showers – fold it, then tuck it between a shoulder strap and the base of the pack. And it provides shade when the sun comes out.

I take an ancient silnylon extended poncho for prolonged rain. Plenty of ventilation. Also keeps my backpack dry without a pack cover, but don’t really need that because HMG. Between showers, easy enough to flip it over my head, tuck it in behind my neck, and leave it dangling. Hoping to find a good silpoly extended poncho someday, because silnylon soaks up too much water.

Both umbrellas and ponchos are less than ideal for trekking pole users, or bushwhacking. But at 8 to 9 ounces each, they are lighter than reasonably rugged rain jackets. With some distinct advantages.

The best rain gear for any trip depends on conditions and the rest of your systems. Good to have lots of choices.

— Rex

In preparation for my upcoming thru-hike of the A.T. I recently just purchased the Montbell Versalite. In making my decision I considered several options including weight (of course) fabric, ventilation, packability, fit, etc. And while admittedly I didn’t consider some of the manufacture’s mentioned in the article or the follow up responses, I’m curious to know if the jacket purchased was considered for the article and/or what everyone’s thoughts are about it…

Jon V:  My next article, that is scheduled for the first week of November, will provide quantitative data on 17 shell jackets.  You may find it useful.  Yes, the Versalite is included in that article.

Stephen S: Really looking forward to that report – I love your scientific detail!
Jon V: I have been using the MontBell Versalite jacket for the past year, and love it. Full zip, pretty long pit zips, a bit more durable 10D face fabric, all for only 6.6oz (actual, my size L). The only downside is it is made from, as far as I can tell, the equivalent of PacLite fabric so the laminate isn’t going to be as durable as a 3-layer fabric. But I have a heavier-duty rain jacket for winter when my pack is heavier. I will say I will probably use my Versalite ski touring / backcountry skiing this year if I won’t be going through many trees. I think the inside layer is really comfortable against my skin when wearing short sleeves underneath, and it vents really well. The only big storm I’ve had it in was a football game where I sat in a TORRENTIAL downpour for about 1.5 hours. I stayed perfectly dry and comfortable. Other than that, it’s just been rain showers while hiking and trail running, where I did not get any more sweaty than I would expect to without rain or wearing a rain jacket.

I’m interested in the conjunction of these 3 statements:

1. By the author: “Evaporation of moisture in clothing requires body heat. Excessive loss of body heat can be uncomfortable or unsafe in cold conditions.” (my added emphasis)

2. By Timmermade: The qualities of Dyneema Composite Fabrics (insert for the general intent of this post: silnylon and silpoly) are well known as a super light weight and super strong shelter material. However, it also has qualities that make it an amazing clothing material. First, it is about as waterproof as it get’s. Fully impermeable. There is no question about “wetting out”. There is no water repellent treatment (DWR) that can rinse off into the environment. Water and moisture simply do not move through it. Second, because of the above quality, it is shockingly warm for little weight. Since it is a full barrier, there is absolutely no evaporative cooling and no convection.(again my added emphasis and also my experience) You can throw this on over a wet shirt and all the cold evaporative cooling stops.

Again for the general purposes include silnylon or silpoly garments that are essentially fully impermeable.

3. Then this closing quote by the author: “That moisture can be your enemy in cold, wet, and windy conditions when evaporative heat losses can lead to thermal stress, cold-induced fatigue, or hypothermia.”

This discussion has been going on as long as BPL has been in existence. What are we trying to accomplish? Are we trying to stay perfectly dry or safely warm? Is it even possible to stay perfectly dry? Can we please everyone and meet every condition; with one garment? Are we trying to stay dry from outside moisture or self-generated moisture? Can we actually stop self generated moisture? Where is the danger?

I guess I’m confused as usual. I agree with the general conclusions of the article related to shoulder situations approaching freezing (way too common around here for about 4-5 months of the year…. but then we don’t have any climbs to really generate peak body heat) but I guess I’m a little confused by the emphasis on multi-layered shell material when one layer oughta do it and by what seems to be almost an over-emphasis on venting. Is it raining so hard and continuously you can’t open the zipper for a few seconds? Don’t want to let out all that warm air do we? And achieving and maintaining a perfect balance between venting and staying warm seems like a pretty delicate balancing act.

My goal is a comfortable stasis, that trends towards a dryer state when I accumulate too much moisture and a cooler state when I accumulate too much heat and a warmer state when I get too cool.

I never desire to be wetter unless it’s really hot out.

The impermeable approach to clothing systems is effectively a vapor barrier system and these should be worn as close to the skin as possible, and not on top of any insulation. Also yes, as in the quote above from Timmermade, highly useful to warm up in an emergency when you are wet.

“My goal is a comfortable stasis, that trends towards a dryer state when I accumulate too much moisture and a cooler state when I accumulate too much heat and a warmer state when I get too cool.”

Well put. Also BTW I really appreciate the noticeable emphasis on excellent content.

I too pay strict attention to the onset of sensible sweat and try to adjust immediately in cooler weather. Sometime the exertion levels just overwhelm efforts to moderate and these difficulties are of course compounded by active and intense precip.

With relation to this: “The impermeable approach to clothing systems is effectively a vapor barrier system and these should be worn as close to the skin as possible, and not on top of any insulation.”

So will an impermeable outer layer that traps self-generated moisture/vapor not also at least moderate the rate of the evaporative heat loss /cooling?  It is my experience that it does. While I’m trying to shed the moisture to a degree I’m also trying to accommodate it to a degree. I can’t control precip but I can regulate my self-generated moisture and warmth.

I guess we’re all trying to achieve that stasis and the discussion is around what is possible and practical.

Also BTW I really appreciate the noticeable emphasis on excellent content.

Thank you! We’re really trying to be more intentional about the content we put out now, and we have a terrific team right now.

So will an impermeable outer layer that traps self-generated moisture/vapor not also at least moderate the rate of the evaporative heat loss /cooling?

Yes, definitely.

What it won’t do is prevent sweating induced by exercise, and while active, it’s incredibly easy to overheat in a VB system in all but very cold temperatures. What it will do is halt insensible (non-exercise-induced) perspiration when inactive.

Besides the stated benefit of being able to vent moisture, I find another big benefit to added ventilation options:

They allow me to keep my jacket on for longer, and regulate my temperature with zippers (or pushing up sleeves etc). Especially when wearing a backpack, having to stop and take off, and then pack, a shell or layer is fairly time consuming.

If instead I can create a lot of venting by opening the front zip, and opening pitzips, or even sticking my arms out of the pitzips, I can cool down a lot, without stopping and taking off my pack.

I have had pitzips and thigh vent zips installed in many pairs of shell jackets and pants for this reason.

They allow me to keep my jacket on for longer, and regulate my temperature with zippers (or pushing up sleeves etc). Especially when wearing a backpack, having to stop and take off, and then pack, a shell or layer is fairly time consuming.

Yes! This is great insight!

The two-layer garments favored by some in the UK for prolonged wet and windy conditions – e.g. Buffalo Systems and Paramo – use long pit zips, two-way zips with flaps, etc. so that they can be worn all day despite changes in conditions and activity levels. I think ventilation options make a lot of sense for windshells too, but the design pressure on these to be SUL is clearly pushing in the opposite direction from relatively heavy zips and stuff. But simple things like the snap on the Arcteryx Incendo that allows one to keep the front zip down without the jacket flapping open are a smart step in the right direction.

Thomas, I’ve been wearing an Outdry EX Featherweight for a couple years. It has lackluster MVTR, probably because the membrane, being on the outside, needs to be thicker. It has tiny dots of a crystalline material embedded in the outer surface to armor that exposed membrane, but I wore a chest bag on a recent trip and the fabric under the bag began to feel a bit queer after a while. I don’t think it can handle prolonged abrasion. But it’s a good step in the right direction. DWR-reliant rainwear seems very 20th century now.

One thing I have not seen is a quantification of the MVTR of a wetted-out conventional 2- or 3-layer jacket. Ryan has pointed out in the past that Gore-tex waders exist, and continue to transport vapor even when submerged. But MVTR must plummet when the face fabric is wetted out. It would be nice to have some quantification of that. This would put something like Outdry EX in better perspective: how does it compare to wetted out conventional fabric? The MVTR of Outdry EX might suck, but maybe not in comparison to a saturated traditional rainjacket.

Shakedry really raised the bar in terms of MVTR and freedom from DWR, but PTFE is pretty weak as a material and Gore seems to have pulled back from their versions touted to be durable enough for light pack use.

I think what we need for non-DWR-reliant rainwear are UHMWPE membranes. UHMWPE is extremely tough and nearly as hydrophobic as PTFE; it would, in theory, be far more suited as an exposed membrane than PTFE. They’ve been electrospinning mats of UHMWPE nanofibers for a while now, but from what I’ve read they’ve not yet been able to get these materials nearly as strong as the traditional gel spun stuff we’re famiilar with from DCF, etc. But I think they will get there. At that point, we might have membranes that are similar structurally to the ones in Neoshell, Ascentshell, Futurelight and Pertex Shield Air, but made with super-tough Dyneema rather than wimpy polyurethane. These would laugh at abrasion even when naked, and breath as well as Shakedry. Probably would still need ventilation though.

By far my favorite new piece of kit is my OR Guardian II Jacket.  Ascentshell fabric actually feels dryer while moving, and pit zips were handy when needed.  Backpacked and Kayaked in the Rockies and Alaska, plus some use closer to home in the humid Mid-Atlantic, couldn’t be happier.

Paired with Marmot Precip Full Zip pants, which I also would recommend.

Acknowledged that they aren’t the most ultralight combination, but for me the weight/features/price trade space was spot on.