Tent vestibules and TENT VESTIBULES

Derrick,
A lot of interesting techniques there.
Wondering how much your single pole weighs.

To clarify a bit, the reference to "arched" or slightly bowed poles was not intended to suggest the arches typically found on freestanding tents. With the stiffness of carbon poles, the arch can be very slight, and two such poles can be opposing and connected at the top with an elbow that creates the slight bow. Granted, including the elbow, about 4 oz is added to the pack, which is not SUL (super ultra light). And if one hikes with at least one pole, nothing is added to pack weight. Double that if you leave the pole behind, as you mention. That is for the more fit and hardy than I.

Another concern about the pyramids is the amount of water that will enter when the door is opened. None of the walls are vertical, so wherever you put the door, water will enter. Granted if the mid is used as a solo, the door half is operating as a vestibule. If used as a duo, not so much.

The main concerns about mids have been the limitations on space from the sharply sloping walls, the pole in the middle, and the additional fabric weight compared to a tunnel or dome structure with the same and more usable volume of space inside. Single and double Pyramids are so popular, it would be useful to know how people cope with living comfortably in them in foul weather. After following this forum for a number of years, questions still remain.

It sounds like you know ahead of time where you will be camping, so bring the right stakes. Otherwise, you would be pretty loaded down with them. I seldom know, so a six shepherd stakes have to do – around 4 oz. Fortunately, the ground in Colorado and Northern New England is more accommodating. This leads to dreaming about tent designs that will require less stakes.

@Samuel

I never know what type of ground I will have to camp on. Each trip usually brings a mixture. All of my trips normally begin in canoe or kayak with hiking in the middle. I only carry MSR Cyclones in the boat, never hiking. The carbon core pegs (I have the ones from HMG) are usable in sand, hard ground and haven even made them work with hard snow. They are the pegs I always hike with.

You are right, a 2 person pyramid with two has not vestibule whatsoever and there is the door opening in rain issue. For 1 person though, I find it the best space, weight and vestibule optimum shelter.

Derrick

If you're hiking with two people and a 'mid, why not just carry two groundcloths/tarps?

One goes inside on the ground
The other can be used with a trekking pole, staked out as a vestibule. Or just staked down directly.

On my Shangri-la there's a loop for hanging it from a branch. Attach tarp there. Or add a small loop if yours doesn't already have one. Reinforce a section a few inches from a corner, put a reinforced hole, and put the corner over the top with the loop sticking up and securing it. It's not perfect but relatively light, cheap, quick, easy and effective. 4-season gale-force winds? Nah. Most snow/rain/normal-wind? Sure.

My thin blue "backpackers" tarp clashes badly with the base-yellow color though. Total downside right there.

-mox

We use a Lunar Duo, and the two vestibules are just big enough for shoes/packs/etc. It's nice to have the flap over the door open, and the other one closed with gear under it. That way gear is covered, and the doorway is clear for entry/exit.

Many times I've considered bringing along a 5×9 tarp to rig up over a door when weather looks less then ideal. I've never cooked in the vestibule, other than while mountaineering (which is not done in the Duo!)

Then again, my wife won't go if the forecast is crappy, so I'm taking the Notch and not the Duo anyway…

By the way, some nice vestibules in the Notch. I really like that little tent.

Ozzy that is exactly what we do. Set it up separate from the ten though.

Derrick

Samuel:

Glavin from SD here. I LOVE your concept (obviously, check out the latest from SD and you will see why). It is actually amazing how close your design is to ours. One comment I wanted to address:

"Surprisingly, wind blown rain was never a problem despite the large openings. Granted, no camping was done above timber/tree line in completely exposed areas."

I have camped extensively with awnings vs. vestibules in the alpine and sub alpine. I also understand the concern about wind blown rain, as many have expressed. And like you, I have never really had a problem (since I solved it just like you, by trimming a waterproof drop door to manage blown rain. This leaves the top open for VIEWING and VENTILATION; both of which are essential to comfort in a storm).

Check out these places I have taken "vestibule-less" shelters (most of these are my old sil-nylon MSR Missing Link):

It seems like that vestibule is not appropriate for that environment

In an extreme alpine area, lots of wind

That wind would blow into the vestibule and put excessive pressure on it

Plus, the wind would blow any rain under the vestibule so it wouldn't be effective

Vestibule would be better suited for a more sheltered location

But your experience must be that it works?

Matt:

Regarding the Tent awning: Check it. In Sil/Nylon this shelter weighs 1 pound 10 ounces, as a side door with 12" awning and trimmable waterproof door (for wind + rain), AND the gear storage awning can be lifted as shown to create a shaded hang out zone, complete with additional door to the inside. The awning can be rolled all the way back for direct star gazing…..

Michael, how do you do that if you are using two trekking poles to keep the shelter up or does this new design come with two poles as well. Thanks,

(Start shipping to Canada…;) )

Dave U:

The two person would require both sets of poles. With the one person, you would need to find a couple of sticks or a separate pair of poles. Note that we ALSO will be offering a set of poles for this shelter seperately.

Jerry:

I agree it seems that way, but my experience is different. Blowing wind + rain, while common, is typicality not severe, even when the wind is blowing hard. I have found that awnings work exceptionally well even when the wind is blowing hard. One thing to note is that awnings make a tent STRONGER in the wind, which is also counter intuitive (check out video here: http://www.zenbivy.com/ZenBivy/Sierra_Designs.html). But the conditions where the wind is blowing hard, right into the door, with enough severity to push water horizontally enough, are pretty rare. And even when you get them, they are manageable while still allowing airflow and viewing at the top of the tent.

"One thing to note is that awnings make a tent STRONGER in the wind"

I think that is a bit inaccurate…

By having an awning and blowing wind directly into it, you are putting all the tent poles/fabric in tension as if you were inflating the tent (i.e. you have a giant kite that is anchored to the ground) – of course it will appear to do better. If you have a closed vestibule, most of the wind passes over the tent, putting the poles in bending (which makes them collapse).

In the wind tunnel tests, how are those tents anchored to the ground? I bet the awning design places significantly more load on the stakes.

Must be me or something. I find some of those designs a bit scary.
Or maybe I have seen a lot worse weather.

Cheers

They are intended for non inclement weather.

"They are intended for non inclement weather."

The mountainous background seems inconsistent with non inclement

Although occasionally it's non inclement there I'm sure

There is no doubt that awnings make shelters stronger in the wind. Yes, the tent blows "up" vs. down, and thus rather than collapsing and bending the poles to reduce the volume of shelter (where it will ultimately break or collapse completely), it remains upright and transfers the tension to what is, by far, the strongest part of the tent: the stake out loop. So, I guess these shelters WILL transfer more force to the stake out loop than a collapsed tent will, but no more than that same shelter (assuming equal surface area) when upright. Yes, an awning forces all of the force to the stake out loop, which is exactly where you want it since it is relatively easy to make any stake out loop completely bomber vs. experiencing failure of the structure itself (which can only be realistically addressed in the field with guy lines).

It is also counter-intuitive that many "tarp-style" shelters are actually stronger than many dome structures. It seems crazy that I would carry an MSR Missing Link into the world of the mountaineering dome, but a Missing Link is actually much stronger in wind (tested to 70MPH in the UW wind tunnel, if memory serves) than most dome tents (most 4 season tents fail at under 50MPH believe it or not).

There are two reasons. Every tent that I have seen fail in wind tunnel testing has failed for two reasons. By far the most common reason is that a pole breaks. The second, far less common failure is fabric tearing due to being "snapped" back and forth repeatedly due to low tension. The pole is actually the weak link, not the fabric. And the poles in dome tents carry the load under "bend" which is their achilles heel.

But a missing link has no bent poles. Think about it, if you wanted to break a section of tent pole, would you push straight on it along it's length (like a trekking pole) or try to bend it to break it (like a dome tent). Of course, you would bend it and it would fail way easier. Poles are MUCH stinger under direct compression than when under pre-bend. Trekking poles structures have much much much stronger frames than dome style shelters, especially since the trekking poles are WAY overbuilt for most tent use, since you use them to support your body weight.

A dome tent "feels" all nice and strong with its tensioned panels and apparent lack of floppiness, but again the truth is hidden. Pre-bent poles tend to reverse themselves under wind (in other works flip around so that they are facing inward rather than outward. In this case, the fabric completely de-tensions, creating a pocket that can hold the wind and force the poles to invert even more. This lack of tension can break the poles, but can also de-tension the fabric enough so that it can begin to flap. Flapping allows acceleration of the fabric to a hard stop, which can make the fabric tear. (check out the Kelty Gunnison, a dome tent, in the video. It immediately collapses the poles at just over 20MPH, and shortly thereafter the poles will break.)

Compare this to the Missing Link, which has no convex shapes to invert into concave shapes. Yes, you lose volume almost immediately in lighter wind compared to a dome which use the poles to create initial tension, but on a Missing Link (or MegaMid, or any similar structure) the seams create guy lines that form a STRAIGHT LINE between the top of the pole and the stake out loop. VERY strong. So while you will lose volume in a tent like this due to the generally larger un-supported panels, the design is way stronger at ultimate failure. It avoids flapping fabric because all the seams are tensioned guy lines, and it loads the poles where they are strongest.

The reason that "pyramid" style shelters are stronger than domes has to do with why we don't generally love the space: most of it is at the bottom and only a minimal amount up high. Not great for livability, but way better in the wind.

Finally, check out the Hercules vestibule in the wind tunnel test and compare it to the awning on the Lightning. The vestibule is the weakest part of the Hercules because it pulls those poles and tries to invert them. It is much stronger from the side where the awnings can hold it up. The Hercules fails because of the vestibule, and would be stronger with an awning on the end like it has on the side.

I know it all seems ass-backwards, I really do. But the testing does not lie…….

Hope folks find this interesting…..

That makes sense

I've always thought pyramid tents were stronger because the pole isn't pre-bent.

Like the "McKinley Tent" from the 1970s. I wonder if they still make them.

What happens when the wind blows away from the awning? Then you will have the same problem as a non awning tent.

You definitely need strong stakes

I had no idea that the Missing Link survived that type of wind speed.

I stand corrected – awnings appear to be ideal for inclement mountain weather!

HA!

Now "ideal" may or may not be correct, but they can certainly work in many conditions. When that wind starts blowing a bunch of snow, the awning certainly becomes less "ideal" and a "proper" vestibule starts to shine.

If you check out our new Convert Shelters for 2015, you see a unique solution to this dichotomy, where the vestibule can zip off and when it is, it is "replaced" by an awning over drop door.

Jerry:

On our tents (say the Lightning in the video), the tents work like every other from the side in the wind. Which is to say that the volume decreases and the poles twist and bend until they flatten. Guy lines are the only current solution to this.

Can I make a very small terminology correction here please?

Quite a few posters have referred to 'dome' tents, with the Kelty Gunnison being mentioned as an example. These are not full dome tents, they are (cheap Asian) pop-ups. Usually, they have fragile throw-over flys, long weak poles and do collapse easily in wind. One might, unkindly, characterise them as Walmart specials. The good dome tents are better called geodesic domes, have anywhere from 4 to 8 poles, and the poles are threaded into the fly. Geos get used in the Himalayas.

Actually, getting a pop-up erected in a wind can be most amusing to watch. There are a number of funny videos on the web showing people spending ages trying to do this – and often failing (or breaking the poles). You get what you pay for.

I am not going to argue about the virtues of straight poles – when nothing blows against them to bend them. But I must point out that the Missing Link is very well named: the design is almost prehistoric, and dates back at least to the A-frame tent with one side extended. It's a very primitive design (1900?), almost a classic 'missing link', and one we graduated from a long time ago. And before you ask, yes, I owned an A frame when I was a little Boy Scout, and yes, I have slept in it with the side extended. Drafty. And I still have it in the cupboard!

Cheers

Observation/Theories for pole-supported shelters

a single pole mid = sheds wind well
straight sidewalls on an inner = better vestibule space
curved, not-flat surfaces = good wind shedding

to get the straight inner sidewalls, you need to add a second pole.
when you add the second pole you can sometimes lose the wind shedding contours of a mid and get a flat surface.

it seems like the trick is to get curved wind-shedding contours between the peaks of the two poles, and have no other place for the wind to catch and create a sail.

My theory is, of pole-supported tents, the TT Stratospires are going to win the real-life ample vestibule/stability/wind-worthiness competition, because it looks the most like two conjoined single mids.

My only credential on this is I was once in a laboratory wind tunnel on a take-your-daughter-to-work-day, long before it was called that.

Katherine:

I have not tested this shelter, but it is clearly an extremely strong design in terms of wind resistance. I'll bet it is super strong. I'd have no qualms about taking that shelter into severe conditions.

Now, since it has a traditional vestibule, it has all the drawbacks of that design (double-the-trouble doors, condensation trapping, no outside viewing in poor weather, gear stored in the door, no safe cooking in poor weather, etc.), but I can say with relative confidence it will be really good in the wind. If it had an awning, it would also be good in the wind, but could solve all those other issues too…..

Gavin,

Your tent is basically a version of a canoeing tent used in eastern Canada from the early canvas tent days. For a forested area it's fine. See The Canadian canoeist and author calls this style of tent the "Campfire Tent". But I agree with Roger Caffin, its' a bit scary for alpine areas.

I feel that my Tarptent Moment DW would be OK for alpine areas, especially with my interior X-ing pole. When it is buttoned down it's very aerodynamic. My TT Scarp 2, even with the two interior X-ing poles and maximum guying, is "not ready for alpine prime time" due to its rectangular, vertical ends. Winds love to push against vertical planes.

Hi Eric:

I actually don't use that tent anymore, but the point I was making was that awnings are stronger in wind, and that tent worked fine for me in many an alpine environment.

Note that winds push equally against equal surface area measured perpendicularly. The force on a horizontal wall is identical the the force on the same size wall if it had a sloping surface; the sloping surface would just present more surface area. It also makes a difference how high the surface area is above the ground, since the ground reduces the winds dramatically. Both of the tarp tents you mention would be very strong in the wind, assuming the bent hoops are guyed out to prevent them from distorting inward.

In fact, the "Moment" would be very strong from the foot end for the exact reasons that the awning on the Lighting is: the tension of the wind on the supporting fabric pulls equally on the hoop, where inward pressure is counter acted by outward pressure due to fabric tension. Both of these designs are stronger in wind than "dome" tents (wedge tents, or whatever you want to call them)….