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TreeHugger 1P tarp weighs only 178g

June 19, 2021 — BarryK

Page first written June 5, 2021

Early this year (2021), I went for a hike with only a Mountainsmith Daylight Lumbar Pack. Blog post:

https://bkhome.org/news/202102/waist-pack-hiking-test-2021.html

I was carrying about 4.5kg, including weight of the lumbar pack, which was a bit too much. Since then, I have been reconsidering my gear, aiming to get the weight down to about 3.5kg.

As part of that exercise, I decided to make my own tent. Yes, I want an extremely light weight tent, but also some comforts and conveniences, including these:

  1. Step-in and step-out, to save my back.
  2. Double-wall, to minimize condensation.
  3. Very quick and simple to erect, minimum of stakes.
  4. Can be used outside or in a shelter.
  5. Extreme light weight, rollup very small.
  6. If possible, some kind of back-rest.

I own a sewing machine, but skill with using it is practically zero. So, add item-7, minimize or even eliminate sewing.

This web page is a tutorial, a how-to, but first I will tell you the end result:

TreeHugger 1P tarp, Mark-1
Weighs only 178g (6.3oz), constructed mostly by glueing, minimal sewing. Featuring step-in and step-out, very easy to erect, use a pole or tie against a tree for "tree hugger" mode (or a wall in a shelter).
In future, intention is to construct a mesh inner tent, so it will become a double-wall tent.

Here it is:

img1

The full implications of this tent will not become apparent until the inner mesh tent is constructed. This will be permanently builtin, and will support the step-in and step-out, as well as make the "tree hugger" backrest usable in all weather. It will also be part of the structural integrity of the tent when erected.

Now for the how-to, tutorial, or DIY steps. I do recommend that you read right through before constructing one of these yourself, as they are a series of blog posts, and some ideas evolved as the project progressed.

1. Consideration of glueing instead of sewing

The proposed ultralight tent is to be made with 10D silnylon, very thin, slippery, and stretchy. Sewing together two layers of that is a challenge, even for experienced sewers. So, I investigated the alternative, to glue:

Longitudinal strength good, but "peel strength" a problem. Note though, not all silnylon is the same -- the chemical composition of the silicone differs, and some have better "peel strength". The one I tested does not, however, other silnylons are under order and will be tested.

Anyway, the silynlon that I already have will, I think, be OK, as long as there is no weakness at a seam where a tear can start. For the tarp, the main place of concern is the ridgeline.

2. Drawing of the original TH1P design

I used an application called "SolveSpace" to plan the "TreeHugger 1P" tent.

The tent is intended to be erected by tying each end to a branch, or on poles. There will be a high-end and a low-end, so essentially the tent is like others out there that erect on a single trekking pole.

This type of tent has a problem with very little head-room when sitting up inside, or rather, trying to sit up, especially if there is also an inner mesh tent. The main problem is that trekking poles are only so long, typically 125cm. So, the original workaround was to use a "spreader bar" just above the head.

The concept has a vertical wall at the head-end, so that if tied to a tree in "tree hugger" mode (or a wall), there is a comfy backrest while in the tent.

The side-entry allows easy step-in and step-out, great for my back, no crawling in and out!

Here are the drawings, but do bear in mind that these are only incomplete approximations to the concepts in my head:

3. Simplified tarp, mark-1 design

As I am an absolute beginner to tent construction, fabrics and sewing, I decided to simplify the tarp, that is, the outer wall of the tent (also known as the "fly"). I did away with the head-spacer bar -- that was going to be a 25cm carbon fibre tube.

Now we are onto actual construction. The tarp is two pieces, to be sewn together along the ridgeline. This blog post describes cutting out the pieces:

4. Glueing hems and ridgeline

I found this to be fairly easy, but then, "easy" is relative and I cannot guarantee that others will find it easy. I was also surprised how little silicone adhesive I used -- I was originally worried that it might increase the weight of the tent too much. Blog post:

One thing to be careful about, is that the hems must be folded so they are on the inside -- for both sides of the tarp.

The instructions are for a "straight cut" ridgeline. However, if you would prefer a "catenary cut" ridgeline, read here:

The above link presents some of the arguments for-and-against a catenary cut. Decide which one you want!

5. Reinforcing for the tie-outs

There are webbing loops at all the tie-out points, and these require reinforcing of the fabric, to spread the forces. I glued these on also:

Again, these are all glued on the inside, that is, the underneath, of the tarp.

6. Folding carbon fibre pole for low-end

Ultimately, I intend that the carbon-fibre pole at the low-end will be sewn into the tent. For now, it is a separate pole.

An important requirement is that it be no longer than 25cm, as I want to be able to lay it flat inside the lumbar pack, or backpack. Originally, that was it, a single 25cm pole, however, I very quickly realised could not get enough foot-room. Needed extra height, so constructed a two-part pole, each segment 25cm:

7. Tie-outs for the ridgeline

This step involved some experimenting. I wanted a light-weight way to hold the pole tips in place. I mostly intend to tie the high-end of the tarp to a branch or tree trunk, however, a pole is an alternative. So the high-end required some kind of "socket" to accept the pole, and it must have sufficient strength and spread the forces. This is what I came up with;

8. Tieouts for the bottom

These are the tie-outs for the four corners, and the middle on the side hems:

Bottom tie-outs and tarp completed — June 05, 2021

And the tarp is ready to use!

Can be used, yes, but for me, this is only stage-1. Next, plan to add "end baffles", and will append to this tutorial when that is done.

Postamble

If you would like to discuss any aspects of this tarp with other MYOGers (Make Your Own Gear -ers), I started this thread on the Australian Bushwalking Forum:

https://bushwalk.com/forum/viewtopic.php?f=53&t=35426

I have a couple of different silnylon ripstop fabrics on order, and intend to compare their "peel strength", with a view to finding the best ones for constructing a glued tent. Tim (forum member 'telemarketim') would like to do this in an organized way, I presume that he would like to come up with some actual strength figures. His request for fabric samples is here:

https://bushwalk.com/forum/viewtopic.php?f=53&t=35134

Note, the silnylon that I have used is ripstop nylon, silicone coated both sides, in fact is permeated with silicone. I am not interested in ripstop fabrics that have polyester one side and silicone the other. Nor am I interested in polyester ripstop, as it is not as strong as nylon. Tim, however, would also like to test sil-poly (polyester ripstop with silicone coating).

Regards,
Barry Kauler
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Tags: light