DIY ZPacks Duplex

[Flydaho]

I've been DIY'ing my own gear for a while now and figured I'd share a project I completed last year before elk season - DIY ZPacks Duplex. When I started this project I knew I wanted to make an ultralight shelter with the following parameters:

- Able to pitch with my trekking poles (no need to carry or manufacturer extra poles which keeps the weight down significantly)
- A solo shelter with enough room for plenty of gear i.e. able to store my bow, pack, boots, everything inside with me
- Big enough to fit two people if we store gear outside under my DIY sheep tarp
- Durable, which probably means I go with a 1.6 oz silpoly material over a 1.1 oz silpoly material (since it is a small shelter, the weight penalty will be minimal) If you have used silnylon before, i suggest you check out silpoly as it is much easier to work with, and has no bias stretch

I started the design by searching through the various ultralight manufacturer websites for potential designs (HMG, kifaru, ZPacks, tarptent, etc). I decided to go with the ZPacks Duplex based on several factors including the very positive independent reviews, the spacious floor plan, and the ease of construction (2 rectangles and 4 triangles).

Here is the ZPacks Duplex.



I started the design process by measuring my trekking pole's max height (54-inches) which will determine the rest of the dimensions. The average max height for carbon ultralight trekking poles if 52-inches, so I ended up going with 52-inches making the shelter more universal (in case I end up getting new trekking poles that are shorter). With the height set at 52-inches, I maximized the spacing between the poles by using the max material width (assumed to be 1.6oz silpoly from ripstopbytheroll.com) of 58-inches minus 2-inches for seam allowance, leaving me with 4'8" between the poles. I then decided to go with a hexagonal shape and made each side 4'8". This shape leaves enough room between the poles to fit 2 sleeping pads/bags in the 2-person configuration, and if I go down to a 1-person configuration it will leave me with plenty of vestibule space for all my gear. Next I had to decide if I wanted a ridgeseam in the design. The seam would be an entry point for water, but it would also be reinforcement for the tension forces between the two trekking poles that are applied during the pitch of the tent. I decided to go with a ridge seam as it will be a stronger design. I then laid out the sides onto a flat rectangle, 58-inches wide and used sketchup to determine I needed 27'11" of fabric. I ordered 10 yards of 1.6oz silpoly from ripstopbytheroll.com as well as 1/2 yard of HyperD 300 for the reinforcement, and 1 yard of gossgrain for the tie-out points and waited for the material to arrive. I also ordered 1/2-inch basting tape from SailRite to use in the seam making process to help me achieve a true double felled seam (not a french felled, or feaux felled seam). I used this method when making a Kifaru Tut hybrid and it worked out very well.

Once the material arrived I started the lay-out process on the hardwood floors, using tape to hold the material down as I measured, marked, and cut it. When it came to the triangles for the sides (which were not equilateral, or right angle triangles) I used string to triangulate the location of the apex and marked it out.

 

[Flydaho]

Part 2

With all the pieces cut out I added the basting tape to the edge and lapped the material. The next step is to roll the seam over and use pins to hold it in place. This results in the "clasped hands" of the flat felled seam that is easy to work with in the sewing machine. The next process is to run the first stitch approximately 1/8 inch in from the edge of the seam, then flip the material over and sew down the other edge. It works best if you can keep tension on the material (on either side of the needle) while sewing the seam. When the tension is released, the seam lays nice and flat, eliminating the bunching of the seam.

 

[Flydaho]

Part 3



I used the HyperD 300 to reinforce the tie-out points at each corner, for the tie-out point midway up the walls on each end, and in the peaks where the trekking poles will go.





I opted not to use a zipper to save weight, and instead I have the doors overlap 6-inches at the top, which tapers down to 0 at the stake. I also wanted to find a better way to attach the tie-out points at the peak. On the ZPacks design, there is a tab that comes off the peak but in my mind that will be a spot for potential tearing, and the trekking pole isn't locked into place. So in my design I have the string pass through the tent material and loop around the trekking poles on the inside with a slipknot. The string passes through the tent material just below the peak through a slit in the material. I reinforced these slits (before cutting them) by using the button-hole attachment on my sewing machine (just like to see on your shirt). This means that the string can be tightened down VERY tight because there is no tension on a small tie-out point on the tent, the string pulls on the trekking pole from the inside and the load is distributed within the tent very well. It makes for a nice taught pitch which will stand up to wind very well. I also added a toggle and gutted 550 cord loop to hold the doors back when rolled up to allow for air flow. Once it was done I seam sealed everything and applied baby powder to the sealer, once dry, to keep it from sticking together.

I also sewed up a stuff sack for the tent (which is ridiculously small) and a stuff sack for the 8 Y-stakes that are required to pitch the tent. All together the tent, stuff sacks, guy-out string, and stakes weighs out at 25.0 ounces. The Z-Packs Duplex (which includes a bathtub floor) weighs 21.0 ounces WITHOUT the stakes. The day before my elk hunt last year, it snowed 10 inches at the trailhead and 18 inches at my camp location. The forecast showed snow every night for the entire week so I ended up packing in my Hilleberg instead so I wasn't able to use the tent and so I can't give you a review on it yet. Once I get a few night in it this summer I'll report back and let you know how I feel about it.

 

[Clarktar]

Awesome!! Well done. Especially like what you did on the ridge seam.

Sent from my SM-G935V using Tapatalk

 

[Flydaho]

Thank you, it turned out fairly well. I'm excited to test it out this summer!

 

[WoodBow]

Looks good man. If you want it to pitch a little tighter and give you some more room inside, you can go to 2 or 3 guy out points on the sides instead of one. I built a mega tarp last year and 3 works well. I just run one continuous line through them and only use 2 stakes.

Don't be afraid to put some tension on it. The material is plenty tough.

 

[Flydaho]

Thanks. I copied ZPacks and only used that 1 guyout point but I like your idea of additional guyout points. I'll have to see about retrofitting it for that.

 

[Flydaho]

Did you make yours out of silnylon? That little bit of stretch makes it easier to get the drum-tight pitch. That's my only knock on the silpoly.

 

[WoodBow]

I used pu coated nylon. Sounds like it has similar properties to what you described. Very easy to work with.

 

[2backcountry]

Nice work, I like it !!

 

[huntbigb]

How much did this cost you?

 

[Flydaho]

My order total from ripstopbytheroll was $69.92. This included 10 yards of 1.1 oz silpoly, 5 yards of 1/2" grosgrain, 1.5mm minicord, 1/2 yard of HyperD 300, and Omni-Tape. I already had the needles (schmetz universal 90/14) and thread (gutterman mara 70). I've used this tent a lot over the last two years and I love it. Super lightweight, surprisingly roomy, and lots of venting options with propping up the doors. Great deal for $70 and a few hours of sewing.