Feb 23, 2009 at 1:10 pm #1234281
Hi all. My wife, two kids, and I have settled on at least two weeks of family backpacking this spring and summer here in California. One glaring hole in our gear is a good tent for the four of us that is lightweight and well ventilated. Kids are 8 and 6 so they aren't quite ready to be sent off on their own.
I am considering a single wall pyramid that would use coupled trekking poles as support. After sewing an overly fancy double wall pyramid tent 25 years ago I have some definite ideas- my existing tent and fly each use 8 guylines! Plus with only a tunnel entrance backed by a mesh door it is a sweatbox when the sun hits it. It weighs 5 pounds even, not including stakes or pole.
My basic idea was a tall pyramid just shy of 10' square with the peak 6' off the ground when pitched low. Ideally the tent will pitch tight with only the four corners staked out, though I would expect to use additional guys under most circumstances.
Design requirements are:
-7'x 7'+ usable space. (Due to sloping roof, overall size will be bigger)
-Complete protection from mosquitos and flies.
-Well ventilated to not overheat when used as bug refuge in afternoon sun.
-Dry in a rainstorm.
-Able to withstand frequent breezes and occasional winds.
-Flexible anchor placement to ease use in rocky areas.
-Setup requiring as few as 4 stakes in calm conditions.
-Durable enough for family use in rocky areas.
Additional, desirable features:
-Flexible pitch height. Tight to ground in stormy conditions and higher for maximum space and ventilation.
-Total weight well under 5 pounds. (Packed weight of my existing tent)
-"mud room" area inside.
-Dark enough to mostly block bright sun and full moon.
-Resist crawling insects.
-Cheap materials would be nice.
With that in mind, I came up with the following ideas:
Nominal size: 10' square minus seam allowances.
6' peak height pitched tight to ground, roughly 7' when hiked up for better ventilation.
Side panels will have a vertical seam to attach two pieces of roughly 60" fabric.
Catenary cut (1/2" per foot?) on corner seams, straight cut on side panel seams.
Fabric will be 1.1 basis weight silnylon with 4 ounce cloth for corner, peak, and guyline reinforcement.
Color will be dark green, medium brown, or something similar. Considering making one side out of the aluminized nylon that Seattle Fabrics sells as 1.3 ounce solar/heat reflective.
Floorless, but hopefully a combination of sodcloths treated with permethrin and a separate groundsheet would keep the creepie crawlies out of my wife's sleeping bag. With a 10'x10' size I think that we shouldn't need a vestibule. For entry and exit in rainy weather we can pull back the groundsheet.
I know a sketch would explain this better, but I plan to provide ventilation/insect protection in the following manner:
Door ventilation- Outer silnylon door with inner netting door, both zippered. Netting door would have lower portion of 1.9 silnylon to keep it from grabbing twigs and sticks.Use water resistant zipper for outer door.
Perimeter ventilation- On bottom edge of non-door sides attach 6" netting strip and 12" sodcloth (1.9 silnylon) strip to that. In foul weather with the tent pitched low to the ground there would be ties going from the join between netting and sodcloth to tie points 6" up the inner sidewalls.
Peak ventilation- The top 18" of the tent will be mesh (mosquito netting possibly doubled with a strong nylon "rawhide" type mesh). Over this would be a rain cap that overlaps a good 6". In fair California weather the rain cap would be left off, for rain it would be attached either by corner straps or possibly zippers to keep wind from blowing rain up under it. In wet, calm weather a prop rod would space the rain cap out from the tent body on the lee side.
26 ounces for basic pyramid with one 72" door zipper. (Per Oware's and MLD's similar items)
2 ounces for seam sealing.
2 ounces for extra guy-out reinforcement.
6 ounces for peak ventilation, cap, and zippers.
9 ounces for 3 sides perimeter mesh/sodcloth.
8 ounces for screen door & zipper.
= 53 oz Tent Subtotal
2 ounces for guylines
5 ounces for 12 stakes (8 strong at corners and midpoints, 4 light to peg down sodcloth/groundsheet.)
12 ounces for groundhseet 9×9 1.35 silnylon.
= 19 oz Accessories Subtotal
= 72 oz Total (4 lb, 8 ounces)
Although these are only estimates, the "creeping featuritis" really adds to the weight. My existing 7×7 double wall pyramid is less than a pound heavier than this estimate.
After adding up the weight estimate I think that I will make changes before building this tent.
Possible areas to save weight are:
Smaller overall size;
Single large window/vent instead of the removable peak cap;
Sewn-in groundsheet instead of the separate sodcloth;
Mesh door covering half instead of all one side.
Please comment as you see fit.Feb 23, 2009 at 1:16 pm #1480111
Another week or so until the rumored 4 person Tarptent is released. Although I admire you for building your own.
I also think that for something that big, I would use a dedicated pole.Feb 23, 2009 at 2:01 pm #1480121
@kegelhoffLocale: Southern Cal
A lot of this is similar to the Cuben mid I built last year and your design sounds really good!
A few things I might comment on:
I don't think I would reduce the overall size based on your family of four and wanting some storage room. THe sloping roof quickly eats up the space just like you thought. I would stick with the 10' x 10'.
Venting …. as Roger once told me, you can NEVER have too many venting options! Granted that yours would breath MUCH better then cuben, I would still look at going with two large window/vents built into the upper section instead of the removable peak. I just use twigs to prop mine open to get maxium airflow when needed.
Sewn in bathtub style ground sheet is a great idea, (Cuben if you want to go lighter) guessing it would be about 7' x 7' and then you could maybe just connect the netting to the ground sheet and take it straight up to the tent wall. Reduce the amount of netting needed to save some weight ?
Might be able to connect two hiking poles together to give you one long 6' center pole …
I hope you make this and take some photos to share with everyone !!!
KevinFeb 23, 2009 at 2:50 pm #1480135
Your basic plan is pretty good.
I would not expect to get a tight fit to the ground with only the corners staked out … I'd add stake loops at the center of each bottom edge
I would add a guy line loop 1/3 the way up the center seam on each side. Also 1/3 the way up each corner edge … although I'd only rig the corner edge guy lines in stronger wind.
The center-panel guy line plus the stake_or_guy_line at the middle of each side's bottom edge will greatly help you maintain interior volume.
1/2 inch per foot is a **LOT** of cat cut. While I'm no expert on that topic, I did get a lot more cat curve than I expected with just a 1 inch curve over a 96 inch Tarptent ridgeline. If you rig the guy lines in the middle of each side panel it will have the effect of pulling the corner edges inward.
I'd skip the sod cloth but that's mainly due to having no experience with them … but I'd use more netting. shoes and misc gear can be used to hold the netting down on the ground.
I would not expect any color of regular silnylon to block out the sun, perhaps the silverized stuff would (pricey!).Feb 23, 2009 at 3:31 pm #1480151
I'm hoping for the dark silnylon to block the moon and sun glare, but not so much direct sunlight. Seattle Fabrics aluminized silnylon is about $30 per side more than regular silnylon. Maybe I should go two sides with it to provide for more sun movement.
On poles- I've played around linking two aluminum trekking poles tip-to-tip. Since there is no lateral load it seems that they will be strong enough. By going tip-to-tip I don't need a grommet at the peak, but maybe grip-to-grip is stronger?.
I've never used a single wall tent before. Oware claims that their 'mids with steep roof pitches let condensation drain and not drip. I'm hoping to get one of the kids to join me in backyard a test-campout with my new Oware OOPS (Tetrahedral Pyramid). This will help to help me to refine some of the design ideas- like how close to the wall we want to be.
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