SlingFin Webtruss - Design Principles

SlingFin Tents have recieved some well-deserved attention. A bit of that is referenced here. This is part 1 of a two part discussion of what went into making these tents. Part 1 here looks at the WebTruss: SlingFin's basic architecture for its mountaineering tents. Part 2 fills in the details.

Transcript

I’m Martin Zemitis and this is the SlingFin WebTruss and I’ve been designing tents for 30 years now, mostly clip tents and pole sleeve tents and I’ve come up with something new called the WebTruss. And it’s patented technology that significantly increases the tent strength.

Devon Brown: If you did this in any other tent on the market you’d be on the floor and right now I’m being suspended by a WebTruss and some tent poles and that’s it.

Martin Zemitis:  I designed the WebTruss because I wanted to make a stronger structure and I wanted to make it easier for mountaineers to use, especially at high altitude and very high winds. The WebTruss solves some design problems I’ve been trying to solve for many years. I was trying to figure out how to add more strength to the structure without adding a lot of weight and that’s kind of difficult. By having a WebTruss, which guided the poles where they needed to be and where you could not have the tent body with the WebTruss during set up it allow…

Devon Brown:  Eventually you basically have two ways of setting up tents; one is you use clips where the poles clip into the clips or the other one is you have pole sleeves. Pole sleeves are a lot better for distributing force over a wide range or a large surface area because the seam is sewn continuously into the tent. Clips hold onto one specific place and put more tension on one area. If you’re in a really high wind situation clip tents tend to be favored by mountaineers because you can lay the tent poles down and use the clips to set up the tent body that way so you have less fabric in the wind until you get your structure out. Pole sleeve tents are slightly less desirable for that because you’re essentially building a kite until you put your last pole in for structure. The WebTruss allows you to build this really porous structure like this in high winds. The wind can whip right through here then you can put your rain fly over the top of it.

Another really nice thing is that everything in here is sewn on grain line so fabric stretches in one direction more than it does in the other. And everywhere this fabric is sewn is in this least direction of stretch so you can tighten this entire structure down around the poles giving a lot of compression. When you put your inner tent inside that will start putting tension on the inner part of the tent, which is a lot like a bicycle wheel. A bicycle wheel is strong by itself, but independently the pieces aren’t as strong as the whole is.

Martin Zemitis:  By having six equal length poles and continuous pole sleeves I was able to create a structure where the poles by themselves are put in place and then afterwards you can apply the flysheet or add the tent body. So if it’s raining for example you just apply the flysheet first and then you set up the tent body afterwards. So depending on the environmental conditions you have many different options on the way you set up the tent. Or if you don’t want the tent body at all you can leave that at home and save some weight.

Devon Brown:  The WebTruss has a bunch of different advantages, one being its versatility in different types of weather. Because you can have your frame independent of the tent body and the rain fly you can choose and pick what you want for what type of situation you’re in. They’ve been multiple occasions where I’ve taken this exact system out to a backpacking trip on the coast of California where it’s been really windy and cold in the morning and the sun comes out it hits 80, 90 degrees and by the end of the night it’s back to 40 and foggy. So this tent can handle all of those conditions really easily.