There are some destinations where conventional waterproof/breathable kit just won’t cut it. I went to one of those pieces earlier this summer and wondered how on earth I would ever keep myself dry. The destinations was the Olympic Peninsula, and the itinerary was a 10-day thru-hike covering a classic North-South route. The gear that I brought with me was none other than the Sierra Designs Pack Trench and Elite Rain Chaps.

Sierra Designs Pack Trench Features:

• Fabric: Durable nylon/polyester shell, soft knit backer, waterproof breathable membrane
• Zippered waistbelt-compatible hand pockets
• Zippered side vents
• YKK main zip with button-closure storm flap
• Extra long length
• Weight: 16.5oz
• MSRP: $250

Sierra Designs Elite Rain Chaps Features:

• Fabric: Durable nylon/polyester shell, soft knit backer, waterproof breathable membrane
• Universal belt/pant attachment
• Adjustable buttoned cuffs
• Elasticized upper leg entrance

• MVTR: 5,500g (ASTM) / 25,000g (JIS)

• Weight: 5oz
• MSRP: $80

Opting for mechanical venting

I like the Olympic Mountains on the Washington State coast, I really do. But there’s no denying they can be a very wet, cloudy place where all you see is trees and the (admittedly stunning) blue water white water washing away glacial silt to the Puget Sound. It’s a good place. I was guiding eight high school students on a 54-day leadership course through the Olympics, and when you’re guiding you really start to think differently about your gear. You need your gear to perform because, as the guide, it’s your responsibility to keep your clients safe. So, as much as possible, gear can’t be a distraction. It needs to work.

I felt a little risky taking the as-yet unproven Sierra Designs rain kit onto the trail for their first test. The numbers for breathability don’t stack up with mainstream waterproof/breathable (WP/B) fabrics – it’s a much less breathable fabric. So why did I take the risk? Instead of relying directly on the fabric to do all the grunt work of both keeping water out and letting sweat/hot air through, Sierra Designs is relying on mechanical ventilation.

What do I mean by mechanical ventilation? Well, it goes like this. Many high-tech shells have pit zips for when you’re working too hard for the fabric to be able to cope. Sierra Designs noticed that many WP/B jackets simply get overwhelmed, either from the inside or the outside, by the demands we put on them. This is especially true for people like me who tend to sweat heavily. It’s just too much for something like Gore or Polartec to handle, really.

So Sierra Designs has expanded on the concept of pit zips and strategically placed similar vents throughout the jacket. So, on the Pack Trench, we have three key vents: the pit zips, mesh-lined pockets that double as vents, and finally two large zippers running up the front/side of the jacket (roughly parallel with the hip bones). These last zippers are the clincher: when you unzip both of them, you basically separate a flap of fabric from the front of the jacket that can now be flopped over your pack’s belt. So, it’s still keeping you dry, but it provides a huge area for cool air to come in onto your torso.

The Elite Rain Chaps work along a similar concept. If you’ve never used chaps (I have, thank you very much, I’m from rural Nevada), it’s a simple concept. Unlike a pair of pants, you basically have two separate ‘legs’ of fabric that you slide your legs through and then attach to either a belt or perhaps something on your jacket. The great thing about chaps as rain gear is that it leaves your butt and crotch completely exposed, allowing them to breathe as freely as permitted by whatever other clothing you’re wearing. With this combination of jacket and chaps, the extra long length of the Pack Trench still provides coverage to keep those areas dry.

The Chaps are an awesome idea and they work well, but I can see two ways that Sierra Designs could improve their construction. First, the plastic clips that you use to attach the chaps to your outfit are on webbing that doesn’t have a significant bar tack at the end, so it’s easy for the clip to slide off. I just tied a knot at the end of the webbing, but this ought to be fixed at the manufacturer’s level. Second, the bottom of the chaps have a snap-button flap that allows you to put your chaps on over boots. This is awesome, but the fabric the snap buttons are mounted in needs to be reinforced. I had to be very delicate about unbuttoning these.

The Pack Trench’s design is mostly solid. Everything works well – Velcro cuffs, zippers, helmet, etc. Lots of protection all over. I was a little skeptical about the permanent pit zips (there’s no zipper – they’re just always open) but for the purposes of summer backpacking I’m content with this since it shaves some weight off the coat.

The Good

• Extra long coverage is really nice
• Mechanical ventilation works – what do you know!
• All zippers pull easily
• Highly durable fabric, excellent for bushwhacking
• Very flexible attachment – can clip onto just about anything if you’re creative

The Bad 

• Snap buttons on chaps aren’t durable
• Webbing on chap straps should be bar tacked into a thicker width at the end
• HEAVY!

The Bottom Line: Sierra Designs Trench and Chaps

I like it. Sierra Designs’ new rain gear was a risk but in the field it performs very well. The concept of mechanical venting served me well on long, rainy days toiling up passes in the Olympics. I would have been drowning in a conventional WP/B shell. There are some downsides: the kit is heavy at 21.5oz for the complete outift, and of course this kit isn’t flexible enough to bring on a climbing or alpine trip. But, for dedicated backpackers, it could be a game-changing find.

Buy Now: Visit Backcountry.com for the Pack Trench or Chaps