This article discusses research we are doing with university students to look at existing standards of design, manufacturing, and materials of ultralight shelters and relate these standards to observed performance in response to adverse environmental conditions.
Shelters of interest to the ultralight backpacking community may be characterized by one or more of the following attributes:
- The use of lightweight fabrics to save weight;
- The use of construction techniques that are less reinforced to save weight;
- The use of construction techniques that are less sophisticated due to the lack of availability of commercial equipment, the desire to minimize labor costs, or design and/or manufacturing inexperience.
- The use of minimal structure (e.g., pole supports) to save weight and increase simplicity.
The combination of these factors results in a product market that is challenging to analyze, because of the wide variability in materials, style, design, and manufacturing quality. In addition, because most of these products are sold direct via the websites of cottage manufacturers, the consumer doesn't have the ability to carefully inspect the products prior to purchase.
Finally, as the trend towards ultralight backpacking continues to expand, users are either trying to extend their ultralight shelters into "shoulder seasons" and even winter, or they desire to add another ultralight shelter to their inventory to handle stormy conditions that may challenge a shelter's design. The two primary storm conditions we are interested in include snow loading and wind resistance.
Thus, we embark on a new journey to investigate the storm resistance of ultralight shelters.
ARTICLE OUTLINE
- Introduction
- Modes of Failure
- Design Considerations
- Snow Loading
- Wind Loading
- Failure Limitation Hypothesis: It's All About the Fabric
- Inadequate Staking
- Pole Breakage
- Seam Failure
- Fabric Panel Failure
- Designing for Fabric Panel Tension
- Testing Methodology
- Summary
# WORDS: 4290
# PHOTOS: 7
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Discussion
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Mark, I currently tie a figure eight at the tie out end of the guy line and loop the guyline through it. My idea with the carabiner would mainly be to make it more modular in winter and save fingers from freezing, Even with the figure eight pre tied it is a bit fiddely to loop it trough with thick gloves.
Also, I had the idea that a carabiner would be a less abrasive interface so that the tie out would last longer. Naturally the carabiner solution is not UL, but 25-30g in total for the 7 attachments is not that much consirering what it adds in comfort for me.
Matt, How long did you cut the HMG guylines? Do you you any tensioners on the upper? Have you ever had the line locs slip? I dont see how doubling up on the guylines would anything the the tie out is the wakest point?
Do you guys know if somebody has ever measured the breaking strenght of the Ultamid (or similar DCF construction) tieouts ?
Wat do you guys think of adding an elastic loop at the tie out to lower the dynamic force peaks and possibly save the tie outs?
Finally, the whole idea behind choosing the Ultamid 4 was to be able to choose more bold parking spots ;-)
“Matt, How long did you cut the HMG guylines? Do you you any tensioners on the upper?”
I replaced all the lines with Lawson’s rope, and his metal bar tensioners. They are easy to use with gloves and they don’t slip.
I adjust the bar tensioners at the top of each attachment, but I also tied small taught line hitches at the bottom of the lines. So each line can technically be adjusted from the top or bottom but the taught line at the bottom is meant to simply tighten on the stake (since the stake choice will vary depending on the conditions.)
Now I understand your desire for using carabiners, (a carabiner rated for climbing will be fine.) But since I’m always guying our the uppers, I don’t think I’d ever feel like I need to disconnect the lines entirely. I do use different colors for the upper, mid, and lower guy lines, making it easier to identify each set from the rest of the lines. While it’s a little colorful, it makes setting up quicker.
Generally speaking, the mid panel guyouts are the only ones that are “optional” and can’t have a lot of tension on them.
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