Wednesday, November 12, 2008

Under This Shall Ye Sleep

Even though I'm writing a book on packs, I can't stop thinking about shelters. I have to admit it -- shelters are endlessly interesting.

A pack is a utensil. It's a utility item. A pack is indispensable, like clothes, but somehow it seems hard to love a pack. I respect packs. I form close relationships with packs. Since I've been dabbling in pack making I've imagined, designed, cut and sewn them, and then used them, and through that process I've learned a lot.

But to me packs are tools, and though I can admire the intelligence that goes into the design of a well-formed tool, and even depend on the tool for my comfort and safety, I don't have much passion about tools. I like and honor good tools but don't love them.

Shelters are different. Shelters are also tools, I guess, but maybe there is something about the way they are used. Boots go on the feet, pants go on the legs, a knife cuts things. Sunglasses block glare. But a shelter enfolds. A shelter is a home. Put up your shelter and you instantly have a place that cares for you, and, in a way, a place that seems to care about you.

Maybe that's why I'm fascinated by shelters.

Maybe not, but it sounds good.

In the past few years I've been exploring ultralight backpacking, and a huge part of that is shelters. Shelters are the biggest of the big three: shelters, packs, and bedding.

If you want to make a switch to light backpacking the best way to start is by looking at the heaviest things you carry, and trying to do something about them first. Don't cut labels off teabags or saw toothbrushes in half. Focus on the big three: shelters, packs, and bedding.

It's likely that you can get the biggest benefit from going to a light shelter.

I did it a little backwards, switching from a four pound, 14 ounce pack to a 12 ounce pack. Then swapping out an 18 ounce stove/cook pot combo and aluminum fuel bottle for a half ounce stove and two ounce cup/pot. Soon I bought a one pound down bag.

Only at the end did I move out of my tent.

It's hard to find a double wall two-person tent under six pounds. Two person tents are convenient, and using one is dumb because they're big and heavy. But they are understandable luxuries in a rainy climate. Understandable after you spend hours each day with rain dancing on your head.

My first shelter move was to buy a single person double wall tent. This helped with bulk, but the weight savings was only a pound and a half. The double wall design can't be pared back very far.

I eventually moved to a hammock, so I'm not typical. I won't shoot for ultimate weight savings because it hurts me to sleep on the ground. The hammock is heavier, and I accept that, because it works for me.

But the big way to save weight and gain convenience is to switch from a double wall tent to a tarp shelter. The average backpacker saves four to six pounds at one shot. Even a huge 8X10 tarp weighs less than a pound. The space under it is like a parade ground. And there are lighter options.

Let's look.

The easiest way to classify tarps is by how you get under them: end, side, or elsewhere. This goes for plain tarps and the various shaped tarps and tent-like tarps.

Traditionally most tarps (and most tents too) have an entry on one narrow end. And it's low. You stoop to enter, or more likely, you crawl. One nice thing about Hennessy hammocks is that you enter on the foot end, underneath. You stand up inside the entry slit and roll backward into bed. Pop off your shoes, hang them outside on the guy line, and you're snug and set for the night.

With a traditional shelter on the ground you have to crouch and crawl, often in wet rain gear, and then you drip all over everything. With a sewn in waterproof floor you have to sleep with the water you bring along in.

Floorless tarps are good with water. Alongside your bed is bare ground. Get a mess on your ground cloth, or some water drops, you sweep it off. Set your wet footwear to the side, let it drain to its heart's content. No wandering water creeps into bed with you.

Most tarps have a traditional rectangular shape, and a traditional narrow-end entry. The rectangular shape fits the body. Lie down and you will be a lot longer than you are wide, and a tarp shaped like this gives good coverage with little waste. A flat tarp with enough tie outs can be jiggered to handle all kinds of weather. See Oware's illustrations. Ray Jardine's tarp book is good too.

A step beyond is the catenary cut tarp. These can be pretty much the same as flat tarps with scalloped edges. Or they can be fairly spacey looking things. The more extreme examples have such deep curves that useful area under them is almost imaginary.

Get something like the Integral Designs "SilWing" or the Kelty "Noah's Tarp" and you have a petty cool device, with a taut pitch. Able to withstand all kinds of gusty winds. But pretty skimpy against rain. Especially with the latter. Catenary cut tarps, at least the more extreme examples, are best as sunshades, though Oware takes a conservative, functional approach, obviously designed by a backpacker.

Just a note: catenary cut means that the fabric is cut so that it hangs naturally. A catenary is a hyperbolic curve that forms when something like a heavy rope or a chain is suspended from its ends. Planning for this by taking slack out during design means that you can pull a tarp tight and have it actually be tight. The cables of a suspension bridge are an example of a catenary curve.

So. We've got variations on the flat tarp, and entry at an end.

Move to the shaped tarp. Ray Jardine is a big proponent of this style. This has gables, or "beaks" as tarpers call them. The beak is an overhang, almost a vestibule, that partly closes off the ends. The tarp (and the beaks) can either be straight cut or catenary cut. The effect is the same either way. These tarps are still rectangular.

Slightly more extreme is the "Patrol Shelter" from Mountain Laurel Designs. It has a beak on the head end and a closed off, squared off foot end. This makes for a quick pitch and a slightly stronger shape offering good protection as long as you point the foot end at the wind. Again, see Oware for examples of pitching flat tarps for best effect. Entry remains at the end. Rectangular tarps are also supported at the ends, either externally by guying out to trees, or by using trekking poles.

Another sort of shape is more cylindrical. More like a hoop tent. Or like some of those bivy sacks with fabric-tensioning wands. The best example of this style is tarp tents from (where else?) Tarptent.com. The "Squall", "Cloudburst", and "Rainshadow" all follow this design.

Fabric is stretched taught between a hoop at the foot end and other support at the head end, where the door is. These are slippery and aerodynamic. They can handle lots of wind. But this is still a stoop-and-crawl kind of design. Support, like that for flat tarps, is at each end.

The next group of single wall shelters is harder to categorize. Let's call it generally "tent like". Tent like because these resemble traditional tents even though they aren't. Their heritage lies between tents and tarps.

This category has variety. Many designs. Take Integral Designs' "Sil Shelter". It's a tent that isn't. It's a sewn together piece of silnylon supported from inside by a single trekking pole. You get in through the generous doorway (at one end), and close the flap behind you. Then you get soaked by condensation. That's pretty well it.

Other designs are also simple, with varying degrees of usability, like Carol Wellman's "Brawyn Shelter", one seamless piece of fabric with a combination vestibule and doorway stitched to one side. Pretty clever. The fabric comes in a 65 inch width, which is good but not quite wide enough to make a shelter all by itself. If you were really small, and the rain came down vertically without any wind, and gently, you could make this idea work without door flaps.

The original design had only a beak, and a permanently open doorway. A later design has a closeable door. But this, like the Sil Shelter, has no ventilation system, so it can get pretty damp inside.

Henry Shires of Tarptent.com and Ron Moak of Six Moon Designs both make innovative and well thought out tent like shelters. The Six Moon Designs "Lunar Duo" has a hexagonal shape. It is nearly round in floor plan, with a big entry taking up two of the six sides. It has a big door, and built in vents to defeat condensation. Tarptent's "Rainbow" and "Double Rainbow" follow the same basic design. Gossamer Gear's "The One" is similar to both of these, but more rectangular, resembling a refinement of the "Brawny Shelter" idea.

These all have side entries.

Integral Designs' "Sil Dome" is a spindle shaped single-hoop, single-wall tent. It looks as though it could have ventilation problems as well. But all single wall tents and all tarps can collect huge sopping amounts of interior condensation.

That's it for end-entry and side-entry shelters. The next group falls in between. These are pyramidal tents. Or pyramidal shelters. Or pyramidal tarps.

Pyramidal thingies.

The Pyramidal tent is an old design. It is reappearing, done up with new fabrics like silnylon, spinnaker fabric, and Cuben Fiber. All pyramidal shelters have one central, internal support, and a large, tall door.

Since this style of shelter has a squarish floor plan, its entry method falls between side and end. Both Mountain Laurel Designs and Oware produce classical pyramidal shelters, with Oware also selling the "Alphamid", a pyramid cut in half vertically. This has a no-overhang vertical doorway so there is no way to leave the door open during a rain. But for solo hikers this shelter is smaller and lighter than traditional pyramids. The internal support is in the doorway rather than the middle of the floor, which is nice.

We could say that the last type of single wall shelter has no ends at all. You can enter from any side. Call this an umbrella design. Mountain Laurel Designs has a pentagonal model called "Trailstar". It's something like a pyramidal shelter with an extra side. Support is in the center where all five panels of fabric join. A second, helper support can go at the apex of two panels to make a vestibule for calm weather use.

This design should be extremely stable since the shelter has solid central support and is guyed out well. Put a stake in the ground at the end of every seam, add one in the middle of every panel, and you have 10 stakes, evenly spaced, each pulling evenly against a central support, like spokes of a wheel. Five seams is a lot, and could cause problems if not sealed religiously.

Other companies, like GoLite, make six sided shelters. These have yet more seams. With the even number of sides supplemented by actual doorways, hexagonal shelters are close to the pyramidal design.

Beyond all of the above there is one last category not really fitting anywhere. The poncho tarp. Six Moon Designs has a "Gatewood Cape" named after the legendary Emma Gatewood who used a plastic shower curtain as her shelter. Six Moon Designs' shelter is fitting as a no-nonsense tribute to her technique. And this sort of dual use clothing is smart for mild conditions, when used by an seasoned traveler, but once it's set up as a shelter the wearer no longer has rain wear available. Entry is along one side. Anyone wanting to experiment can easily make one by sewing a hood into a single piece of fabric. No seams needed.

Check out the links below to see what's available. Maybe you can invent a new style. Let me know. I'm interested.

References:

Brawny Tarp at Backpackinglight.com
GoLite
Gossamer Gear
Integral Designs
Kelty
Mountain Laurel Designs
Oware
More Oware
Six Moon Designs
Tarptent.com
The Ray-Way Tarp Book


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