Single Wall Pyramid- peak vent or not?
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Jim W.
(jimqpublic) - MLife

Locale: So-Cal
Single Wall Pyramid- peak vent or not? on 03/03/2009 17:07:22 MST Print View

I'm re-thinking my designs for a rather complex peak venting arrangement in my planned MYOG 4 person pyramid. My uses will mostly be summer in California, where shade and bug protection will be more important 90% of the time than rain protection.

It will be a steep walled 10x10 pyramid with 6' roof height. It seems that this will be plenty steep for condensation to run off without dripping, even when closed up in a rainstorm.

One full side will have a netting inner door. Most of the time we will have the silnylon outer door tied open. There will be perimeter netting at the base of the other 3 walls. The wall opposite the door will be made of "solar/heat reflective" aluminized silnylon.

With all this, is peak venting needed? I note that Mountain Laurel Designs has dropped the vent from their pyramid.

Thanks,
Jim

EDIT 12/18/2009:
All talk and no action... I ended up buying a Black Diamond Mega Light. I liked the vent, I liked the nice carbon fiber pole, I liked the sale price I found (cheaper than buying the fabric and pole).

Now it's time to figure out the bug issue. Full nest or perimeter net plus sil floor?

Edited by jimqpublic on 12/18/2009 10:28:41 MST.

Rick Dreher
(halfturbo) - MLife

Locale: Northernish California
Re: Single Wall Pyramid- peak vent or not? on 03/03/2009 17:23:01 MST Print View

Hi Jim,

I simply don't know the answer to a question this complex, but will guess that with only the netting door deployed condensation won't be much of an issue, except perhaps in soggy settings on cool, calm nights. Closed up against the rain, however, I'll further guess that a good deal of condensation will form. Even if this moisture has a tendency to track down the walls rather than drip, the time will come when you brush against the walls or hit the center pole or receive a gust of wind that will send a shower down upon you and your gear. IMHO that's worth avoiding, if possible.

I have a couple of teepee style shelters, both with top vents and both of which still gather quite a bit of condensation in the right conditions. Anything you can reasonably do to reduce the accumulation is a plus. That's easy for me to say, since I'm not doing the sewing!

Nick Gatel
(ngatel) - MLife

Locale: Southern California
vent on 03/03/2009 18:26:51 MST Print View

Jim,

Years ago I had a Chouinard Pyramid, which I could pitch off the ground. I got rid of it because of the condensation. In the winter inside, I often would have a sheet of ice along all the sides. This tent could sleep 2 or 3 (tight), and with just me I had the condensation. I don't know if it was the shape, but my Wild Oasis gets less condensation. So I would definitely look into venting. Theoretically, I would imagine the vent gives air the ability to flow.

Tim Marshall
(MarshLaw303) - MLife

Locale: Minnesota
Re: Single Wall Pyramid- peak vent or not? on 03/03/2009 18:30:27 MST Print View

Quoted from MLD's mid page

"The apex vent has been deleted for 2009. Not enough venting is possible in a Mid even with a LARGE vent for the trade off of wind and snow blowing in through the vent in harsh weather. Large Mids with small vents are pretty much useless and function only as a cosmetic "feature" that decreases strength and increases weight. I trust Brent and Erin's 300+ nights in this Mid for every type of harsh weather imaginable on this one!"

If anybody would know i guess it's them.

What i have played with is the idea of losing the sil door panels in favor of mesh and adding an anex fly. This would be useless in winter, which requires you to own multiple shelters and steal a major perk from the mid but would vent much better than a little peak vent and keep rain out when entering and exiting. The "door" would always be open and you choose if you want the screen down or not.

Vented Mid

This pic shows with small anex fly and half sil door half mesh. You get the idea.

-Tim

Edited by MarshLaw303 on 03/03/2009 18:34:50 MST.

Jim W.
(jimqpublic) - MLife

Locale: So-Cal
Re: Single Wall Pyramid- peak vent or not? on 03/03/2009 20:28:35 MST Print View

The condensation issue is one of the reasons for an oversized pyramid with steep walls- but only experience will tell.

Nick- I -think- that this design, using a steep pitch and hydrophobic silnylon, will sheet the water off much better than the Choinard model with hydrophilic urethane nylon.

Tim- I'm trying to keep both the design and setup simple. The front beak will require a front guy, which might in turn require a rear guy to balance the tension. (based solely on experience with my very different pyramid). Great graphic by the way. Did you use sketchup?

Tim Marshall
(MarshLaw303) - MLife

Locale: Minnesota
Re: Re: Single Wall Pyramid- peak vent or not? on 03/03/2009 20:48:05 MST Print View

Yes sketchup

How do you enter and exit in the rain without getting water inside?

That is what has kept me from switching to a mid shelter. Whats the point if it's soaked inside from entry/exit.

I have seen others use a separate fly over the door to offer the same coverage. It didn't look like it changed the tension of the pitch, but only trying it would tell for sure.

-Tim

David Goodyear
(dmgoody) - MLife

Locale: mid-west
check out this guy's rendition on 03/03/2009 20:53:53 MST Print View

I have been looking at making one of these for a while. I have no winter shelter and cant part with 5 bills.

link http://hikinghq.net/forum/showthread.php?t=2815

What do you think?

Dave

P.S. Tim you could rig a couple of clips to fold the beak over to shut the mesh door in a bad blowing snow storm. This would keep the blowing snow out. The beak in full extention would keep the rain out as you enter and leave. I would even suggest that you design the beak to come out farther and lower and make the mid higher and more tipi like. What do you think?

Edited by dmgoody on 03/03/2009 21:06:17 MST.

Jim W.
(jimqpublic) - MLife

Locale: So-Cal
Single Wall Pyramid- Rain Entry on 03/03/2009 21:48:05 MST Print View

Tim,

My hope for the infrequent rain here is that opening half the door, zipped 2/3 of the way to the peak will wet only a small portion of the interior. One of my early thoughts was a second pole right at the front to create a vertical endwall, but again that's getting more complicated for the occasional shower. I'm back to a floorless shelter with small groundcloths, so we could arrange ourselves to leave the area near the door clear. Certainly a small tarp could be rigged to keep rain off, but I'd rather not have it part of the standard setup for the normally dry weather here.

The reasons to go floorless are threefold:
1. Shoes. Especially if we're escaping into the tent to quickly escape mosquitoes or rain, the kids being able to enter with shoes on is a big plus.
2. Flexible setup/takedown. Especially in wet weather the ability to set up the roof and get inside quickly seems a good idea.
3. Bed wetting. It's getting less frequent, but a certain child sometimes lets loose. He did a good job of flooding the tent when it happened camping. A synthetic topbag and separate groundsheet seems a good way to contain the problem.

Edited by jimqpublic on 03/03/2009 21:52:09 MST.

Kevin Egelhoff
(kegelhoff) - F

Locale: Southern Cal
Re: Re: Single Wall Pyramid- peak vent or not? on 03/03/2009 22:33:24 MST Print View

Tim,
Very practical and great looking design. I had looked at making a new cuben shelter this year and wanted to do something similar to your design but extend the beak section even further and use the second hiking pole as the support for the beak. I have some pretty crazy ideas on how all the walls are going to be made using lots of no-seeum for the double wall and venting similar to your door but on all four walls. Having built my first all Cuben shelter, VENTING is something that must be really well thought out well in your design!

Soooo, when are you going to start playing in Cuben so I don't have to build this thing and can just have YOU make it for me???
Kevin

Edited by kegelhoff on 03/03/2009 22:37:25 MST.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Single Wall Pyramid- Rain Entry on 03/03/2009 22:46:41 MST Print View

Jim,

One of the drawbacks or the pryamids is the need to put the single pole in the middle of your sleeping area. Have you considered something of an offset, which might make it easier to design the 2nd pole to pull out the beak and enable the extra ventilation. You might want to check out some the manufacturers and see if there is a design that you can adapt.

But what I would consider is a large silnylon tarp, maybe 8 X 16, and you could just use an A-frame setup. Only issue would be getting a tight enough tarpline. But there lots of possibilities... and again, we are not handling your insect issue, which would require netting. I think geometrically you will get much more square footage of living space/sq foot of material with an A-frame. Plus it would be easier to design. Just brainstorming here for you. :)

Jim W.
(jimqpublic) - MLife

Locale: So-Cal
Re: Single Wall Pyramid- peak vent or not? on 03/04/2009 00:18:51 MST Print View

Nick,
My existing double-wall pyramid is 7' square and the center pole has never really been a problem. The 10x10 pyramid with edges 6" off the ground ought to give at least 8x8 of usable space.

I'm hoping that using a symmetrical pyramid and short guys I can adjust the center pole to combat sag, vs. having to go outside to adjust 16 guy lines like I do now!

Rod Lawlor
(Rod_Lawlor) - MLife

Locale: Australia
No vent on 03/04/2009 01:18:09 MST Print View

Just a tarp for when it rains. A diamond shape will give you the best bang for your buck weight wise, but a bigger rectangle will help the livability in rain HUGELY. (Check the avatar)Sleep a family of 4

Edited by Rod_Lawlor on 03/04/2009 01:19:30 MST.