Some gear questions I have been thinking about, and wanted to throw out to the HF tribe for educational purposes of us all.
1. We all know that a Silnylon tarp stretches, and therefore the reasons for tarp tensioners and catenary cut construction exists and are employed.
Question:
A. Does silnylon stretch if it is dry?
Everything stretches. Concrete, steel, fabric. Its the basics of physics. If you take something and lay it in the sun, it warms and relaxes (best example is a piece of gum...set it on your dash in the car under the sun and it will melt. A vague reference, but the same thing happens to everything. Your pistons in your cars motor are made a couple thousands of an inch smaller to allow for expansion. Your tarp fabric does the same thing when exposed to the elements. You just took it out of a controlled environment (your pack), and now the sun heats the fabric, or water moistens the fabric.) So, yes, sil will expand/stretch when dry. Cuben and spinn does too, just not as noticeable. Percentages...
B. Does it stretch only when wet?
Refer to my first answer.
It is more noticeable when wet. Another set of factors come in to play...Your line is also getting wet and the trees, the weight of the water on the fabric adds additional stress to a previously tensioned tarp. The newer lines help some, but if you've ever tensioned a tarp with paracord, the stretch factor is apparent, more the line stretching, but it a good example of stretch. Throw some water into the equation, the fibers become relaxed and lubricated and stretch occurs.
C. If it has stretched when dry, will it continue to stretch when it gets wet?
Yes, its a never ending cycle of stretch, it will occur, but to what degree, or percentage, is the question.
D. If I have already tightened my tarp tieouts after it has rained, or heavy fog, and it has caused the silnylon tarp to stretch, should I loosen the tieouts when the tarp has dried, to alleviate the increased forces at the tie out point? And therefore reliefing the forces applied to the tarp material in general, preventing a failure.
I don't feel it's neccessary, but if it worries you, then adjust accordingly. Peace of mind is priceless.
2. Concerning tarp to ridgline connection hardware.
Question:
A. What is the general breaking point of a plastic type D-ring?
Depends on the d-ring. If there actually plastic, not much. Most new hardware is made from higher strength composites, not straight plastic. So the strength varies from brand to brand and material used by said brand or company. And how the force is applied and the width of the area.
Static load and dynamic shock load are two different beasts. A d-ring might hold 60 lbs when slowly wieghted. But drop 60 lb from a foot or two tied to the same d-ring...FAIL! Wind will apply dynamic shock load.
B. What is the general breaking point of an S-biner, whether it is plasic or metal and differing sizes.
Refer to the above answer. Not all materials are the same and fatigue and stress occur each time. Again, is it a slow steady pressure or a shock load, the physics involved vary greatly.
C. With high technology lines available today for ridgeline material (Dyneema), can it be assumed that no water will absorbed, and that failure would only be from abrasion, since the tensile strength outweights the forces applied greatly?
Water effects everything, its all about percentages of absorbtion. To say "no water will be absorbed" is misleading. Your line is wet, your tie outs are wet, your tarp is wet, all add to the effect of "something is stretching".
Also, the ground is now getting wet, which allows the stake to move some, even a little, which gives an added illusion that your tarp is stretching.
Combined, all these little amounts of stretch add up. It's all about compensating for the inevitable. Stretch will occur.
3. Silnylon Tarp Damage prevention.
Question:
A. What are the pros and cons of using stakes.
Stakes a simple easy way to attach your tarp/guylines to the ground. Stakes come in different materials and sizes, each with there own benefits and drawbacks. Size, weight, cost and durability all play a factor in which ones YOU choose to carry. The soil that the stake is used in plays a big factor to their holding power. Clay might be hard as a rock when dry, add a little rain and the clay turns to mush, and the stakes work free..
Stakes can be a fail safe. I've tripped over my guyline 
, and was happy the stake sprung free and the tarp did not rip. Something has got to give, either the stake, the guyline or the tarp fabric, its your choice..
B. What are the pros and cons of using natural anchors. I.E.:Rocks, trees, bushes.
Agian, something's got to give. Natural anchors have to be used sometimes, but take into consideration something has to be the weak link. A big gust of wind, or an clumsy hammocker and damage can occur. If the anchor can move to relieve the stress, then thats good. If the anchor doesn't move and the guyline breaks, that can be repaired/replaced, if you carry spare line. Or just tie another knot in the line.
I would rather put a weak link into the stake or guyline, save my tarp.
Tying to major structures, like large trees and rocks can and will work. Just realize the potential for damage and tread lightly.
Well...what are your imputs team?
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Originally Posted by Barefoot Child
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