Tarp Tent Moment Li?

The Moment DW design is quite fabric efficient and the weight savings would not be as much as you think. Best guess is that a Dyneema version would save 7-8 ounces so the end weight for such a combo would be in the 28-29 ounce range.

-H

Disclaimer: The opinions I’m going to share here are entirely speculative and largely based on intuitition. I am not an engineer and the most complicated thing I’ve ever made out of fabric was a tapered stuff sack. I wonder if anyone would indulge me in a critique here. Henry, do I have this correct at all?

I feel like the Moment is a design that relies on the inherent stretch of silnylon in order to accommodate the compound curves created by taking two panels and stretching them into a cone shape. (Is there a term that describes a section of a cone? Maybe this is a mild hyperbolic parabaloid because of the stretch of the fabric? I digress)

When I look at the photo above I  imagine tension going continuously from the pitchlock end to the hoop at the midpoint of the tent. I imagine the tension going at multiple, dynamic angles: some are oriented along the fibers of the fabric while others are angled diagonally (along the fabric bias where it stretches more).

DCF, as I understand it, doesn’t stretch along the bias well and when it does stretch, it deforms permanently. I think that bias loads shear the fibers from the mylar face because the mylar does not stretch in an elastic manner. I believe this stresses the adhesive holding everything together and can even cause small tears in the mylar. Please correct me if I’m wrong.

I’m pretty sure a DCF Moment would have some saggy bits and the design would distort/stretch the DCF in ways that compromise its structure.

The Notch uses three panels rather than two. I suspect the DCF is oriented with the fibers going the long axis or each panel. This means you are loading the fibers and not the adhesive/mylar with a diagonal bias. I feel like the Notch is a design much more suited for DCF than the Moment. Further evidence for this is the fact that Henry makes the Notch in DCF but not the Moment. 🙂

Brad, why not use the Notch with a couple of collapsible poles? I believe you can buy them from Tarptent (or several other sources). The Notch is double wall too. Personally, I think the Notch is an absolutely perfect shelter, other than is packed length. If you can live with it’s packed length then my recommendation is to go with a Notch. It’s a really nice tent.

Huh. Interesting. On closer inspection I believe the fabric is oriented along the blue lines. I was expecting it to be oriented along the yellow line.

The Moment DW design is quite fabric efficient and the weight savings would not be as much as you think. Best guess is that a Dyneema version would save 7-8 ounces so the end weight for such a combo would be in the 28-29 ounce range.

Thanks Henry.

I could live with 28-29 oz’s!

I came up with my guesstimate for the Moment as 25% because that’s what the Notch Li saves… But I forgot the Moment has a pole, while the Notch doesn’t – that obviously skews the % of weight savings.

Still, at 28-29 oz’s, that’s fantastic given a solid interior and the ability to erect the tent with the inner attached during bad weather. I’m in!

Tarptent could finally update their fabrics and go with a 20D silnylon or silpoly – that would make a decent dent in the weight by itself. Even very fabric conservative MLD has moved to 20D silnylon for most (all?) of their shelters and their floors.

A silpoly Notch/Moment and a way that’s actually easy to remove the end struts (or have them fold in half) would be a winner for most I think.

I think there are poles available for the Notch Li. I use trekking poles, but if you like the tent, maybe explore the option of a Notch Li with provided poles. You’d still get the weight savings.

I have both, and I like the space in the Moment better. But the weight savings for the Notch is totally worth the loss of space!

Sorry, small detour, but does 20D silnylon behave the same as 30D (assuming all else is equal) with respect to sag/moisture retention?

I also think a more modern fabric choice would benefit Tarptent’s designs. There are a lot of fabrics out there now with excellent characteristics at lighter weights. I like the no-sag quality of silpoly. That said, I own and use a Moment DW and love it. I would love it even better if it were lighter…even if just a little lighter (if I’m fiddling with my spoon to shave a gram or two, ounces count for a lot!).

Re the shape not suitable for DCF.

The similar design  Terra Nova Ultra was made of Cuben Fibre and around over 10 years ago.

https://backpackinglight.com/terra_nova_laser_ultra_1_tent_review/

I had the Nylon tent it was based on – The Laser Photon.  It was ok, though not as well cut, solid or sophisticated featured as the Moment.

I think there are poles available for the Notch Li. I use trekking poles, but if you like the tent, maybe explore the option of a Notch Li with provided poles. You’d still get the weight savings.

Indeed, that is true. The appropriate sized Ruta Locura Carbon Poles (39″) w/ Adjusters weigh 6.44 oz for the pair. That would bump the solid interior Notch Li to 27.75 oz’s (or around 31.75 oz’s +/- w/ Tyvek).

Even though it’s not necessary for this tent, I always carry a Tyvek ground cloth in order to sleep out tentless should I want to.

I just prefer the Moment’s design, and I really think the Notch is at its best with trekking poles given the broad handle top of any given trekking pole will give better, more positive tent support than the aftermarket poles which will require some sort of larger base attachment to keep from sinking in soft soils.

I’ve always thought the Moment is a deceptively simple, elegant design…

Re: Would Dyneema lend itself to the Moment design?  Yes, it does. A set of curved surfaces are certainly possible with non stretch fabrics as long as the surfaces are not doubly curved and the patterns are designed/cut correctly.  It can be tricky sometimes–we went through this with the Double Rainbow Li–to get it right because along with mathematical surface constraints there are fabric shrinkages introduced by fabric handing and seaming/taping which make the final product not as intended. Consequently you have the grow the patterns certain percentages to compensate for the unavoidable shrinkages during manufacturing.

Re: other fabrics, we’re working on it…

-H

Henry, thanks for your input on the forum and your patience with all these questions…

Henry, thanks for your input on the forum and your patience with all these questions…

Yes. This!!

Henry, have you talked to the guys at Aluula? I can envision them making the best tent fabric ever made with enough encouragement.

Jason. we have had contact with them in the past and looked at samples.  Like all fabrics, the various options have limitations, and we think our current fabrics are better at least for the time being but we’ll keep checking back.