Monday, June 18, 2012

Rainy weather + tent design

It's been a wet spring here in the Pacific Northwest, but everyone knows Seattle is a wet place. It turns out that spring is often wet around here - we're a soggy bunch of folks. In fact, Washington is called The Evergreen State and you don't get to be so green without a bunch of rainfall.

Because of all this water falling from the sky we find that outdoor people here are pretty tuned into the details that make a tent livable in the rain. And it's no coincidence that our tents include these things. Here are a few of them:

  • Vestibules - When it rains for days, a vestibule really shines, so to speak. Little details can make a big difference here. An example is the importance of vertical inner tent doors and a vestibule design that keeps water from running into the inner tent when the outer door is open. A seemingly simple thing with profound repercussions when it's not done well. Vestibules allow wet gear to remain out of the inner tent and maybe even dry a little. Cooking in a vestibule (be careful!) is also a great luxury.  
  • High quality fabrics and coatings - Light is right, but in wet conditions there's a limit to how light floor and fly fabric can go without compromising durability and waterproofness (which are linked by the way!). Our philosophy has always been to build gear that will work well in use and over time (hence our tagline: Expedition Equipment). The best example of this commitment in action is in the floors of our tents. Our 4-season tents use 10,000mm water column (14+ PSI) floors and our 3-season models use 5,000mm (7+ PSI). These numbers refer to a standard waterproofness test that reveals how much pressure the coating can withstand. Both of these tent standards far exceed the typical tent on the market. All our flies and floors are also factory seam taped as well. There is a price to be paid, of course, both in a more expensive tent and one that is a little bit heavier, but we think it's worth it. And when your tent site is awash in rainwater in the middle of the night, we think you will agree. 
  • Strong guyline attachment points - All but one of our tents (Andromeda II) are considered "free standing," but when it's windy and wet that's simply not enough stability. So all of our tents, including our 3-season endoskeleton (poles on inner tent) designs, allow at least some guylines to be anchored directly to the pole structure. In the case of our 4-season exoskeleton (poles on fly) tents, there are many points of guyline attachment that originate on the pole sleeve. In wind tunnel testing and extensive field tests we've learned a great deal about guyline placement and incorporated that knowledge into our designs. 
  • Ripstop polyester fly fabric - In Europe, Exped sells a number of our tents in both polyester and silicone coated nylon versions, and has for many years. Silicone nylon has a slightly higher tear resistance and for this reason has a following. But we don't offer them here in North America. All our tents, except the single wall Polaris, are sold with polyester flies, and the reason is that old rain again. Because we make the same design in both fabrics we've been able to compare them directly - same exact design but simply different fly fabrics. In wet conditions we find polyester to be superior for two very important reasons - it doesn't sag when it gets wet and dries rapidly. Silicone nylon, when it gets wet, has a tendency to stretch and sag, requiring a re-staking job to regain a taut pitch - and it's slower to dry. We've found this to be less than desirable in wet climates and therefore sell only polyester flies. And after years of use we simply do not find the tear strength difference to be an issue.