Safety tethers. Why webbing?

[thinwater]

Originally Posted by saishyamnilgiri

Webbing may be much easier to cut through in case of an emergency. Also they will be much easier to inspect for chaff, wear and tear, general damage compared to round climbing rope.

Uhh... No. I've been climbing all over the US for 35 years, and I don't think there is any basis for either statement. I've worn and cut both in a mountaineering environment. Both are reasonable cut resistant, and either can be sliced with e few strokes when under tension. Chafe on either is obvious, but only rope has a protected core.

Only rope is designed for shock absorption. Webbing is designed to be non-stretch. In rock climbing systems, ONLY the rope is expected to absorb shock. Everything else is static, to reduce movement and thus chafe.

The arguments against rope are:

1. Greater cost
2. Difficulty splicing
3. Rolling under foot

... and that is all.


Jacklines are a far more complex engineering case, in many ways, boat-specific.

[Recy]

What is a daisy chain?

[Benz]

Originally Posted by Recy

What is a daisy chain?

Length of webbing with loops sewn in all along it. Google for pictures.

[estarzinger]

Originally Posted by thinwater

The arguments against rope are:

1. Greater cost
2. Difficulty splicing
3. Rolling under foot

... and that is all.

Thin, you are letting your enthusiasm for dynamic rope overcome your reason

Webbing has several fundamental properties and several practical properties beyond your list.

Just for example of one of the fundamental properties is that it is less affected by small bends (because it's d is thin) than similar strength rope.

And just for example on the practical properties is that tubular Webbing can have elastic threaded thru, which automatically nicely collects the longer tether so you are not tripping on it.

There are additional items in both the fundamental and practical categories . . . But I don't want to write a book here.

Generally I think whichever tether you are most likely to actually carry/have with you is the winner. If it is too awkward to have with you and to use, then it does not matter what other wonderful features it has.

As you know, I personally chose a "third way", neither web nor dynamic line.

[transmitterdan]

It is easy to sew into webbing a "fuse" to indicate when the tether has seen an overload condition. But it is hard for a DIYer to do it correctly. It takes testing and tight quality control to sew the fuse the same every time.

[estarzinger]

You can sew "overload flags" and "zipper shock absorption" into both webbing and rope. They are however usually tidier in webbing.

The zipper shock absorber does not take a huge amount of skill. You just need to make sure it will unzip somewhere above "normal load" but below "spine breaking load"

[thinwater]

Originally Posted by estarzinger

Thin, you are letting your enthusiasm for dynamic rope overcome your reason

Webbing has several fundamental properties and several practical properties beyond your list.

Just for example of one of the fundamental properties is that it is less affected by small bends (because it's d is thin) than similar strength rope.

And just for example on the practical properties is that tubular Webbing can have elastic threaded thru, which automatically nicely collects the longer tether so you are not tripping on it.

There are additional items in both the fundamental and practical categories . . . But I don't want to write a book here.

Generally I think whichever tether you are most likely to actually carry/have with you is the winner. If it is too awkward to have with you and to use, then it does not matter what other wonderful features it has.

As you know, I personally chose a "third way", neither web nor dynamic line.

Interesting points that no one brought up. Good.

Bend radius. True, one of the properties that makes it good for climbing anchors. But I'm not sure that loading over an edge has shown to be a problem. The CE standard does not include an edge test. However, climbing ropes are drop tested over a carabiner using a very severe drop. Thus the point is true but I think not relevant. Consider how low the frequency of climbing rope failure is, given a huge fall history around sharp rocks. For example, a Wichard or Gibb hook would fail climbing carabiner standards because of the narrow bearing surface, but it only really matters if a rope is running across it, not a static fall. But you could argue, for example, that a Gibb hook on rope jackline (different topic) is less safe. But is that a case of the wrong hook design (I think so)? I dislike Wichard and Gibb hooks for other reasons.

Bungees. Good point and one of the reasons I wish elastic webbing were available. Not quite enough to persuade me, but close.

Non-dynamic. We're going to disagree here. Perhaps it is a difference in the boat design and how we use it, but I would have suffered rib and back injuries by now and I simply see insufficient reason to make such an unnecessary compromise. The World Sailing standard now includes a drop test, but lamentably, not a reasonable (survivable) impact force limit. But perhaps we will get there. Perhaps new materials will become available. But I believe non-dynamic is dead and should be buried. Can they be used for spot anchors? Sure.

The most important things are that the system is useable, fits the boat and how it is used, and is practiced with. My first few generations did not fully meet these requirements. Most systems don't. But it does now. Some aspects are non-conventional, such as my jackline material choice and location, and relatively long tether leg (9'--6' requires too much reclipping) , because it is a catamaran. That simply gets back to the "fits the boat" requirement.

[estarzinger]

Thin,

question of curiosity - when you 'looked at' webbing - did you only look at polyester, or did you also include nylon? I'v only heard you mention 'webbing' and not separate it into the (quite) different materials.

Polyester is by far preferred for jacklines, and I guess climbers are using mostly spectra today, but with your interest in tether elasticity, nylon would be the choice. Nylon would give you several x times the elasticity of polyester (and while less than a dynamic rope, way more than a static rope).

[ImaginaryNumber]

Originally Posted by estarzinger

... As you know, I personally chose a "third way", neither web nor dynamic line.

Evans,

I'd be curious to know your "third way". I suppose you wrote about it on your now-defunct web site. Huge loss for us supplicants I wish I'd "vacuumed" your site clean before it disappeared.

[estarzinger]

^^ I had short tethers fixed at all work stations, and I made/carried extremely light/compact (Dyneema) tethers that could be carried in any pocket and you would not notice them, so they could always be with me.

The objectives were to (1) always have a tether available, and (2) always as short as practical to not allow going overboard and (3) not allow any meaningful fall distance. My system accomplished that.

I played around with adding shock load absorption (via a "zipper stress release") but did not think it added much given the other system characteristics.

This all worked well for us. I would do it again. . . . Might work less well for others with different procedure or philosophy.

[thinwater]

Originally Posted by estarzinger

Thin,

question of curiosity - when you 'looked at' webbing - did you only look at polyester, or did you also include nylon? I'v only heard you mention 'webbing' and not separate it into the (quite) different materials.

Polyester is by far preferred for jacklines, and I guess climbers are using mostly spectra today, but with your interest in tether elasticity, nylon would be the choice. Nylon would give you several x times the elasticity of polyester (and while less than a dynamic rope, way more than a static rope).

Webbing: Tethers, webbing only. Polyester would not pass the drop test, and nylon will with a small safety margin. To my limited knowledge, the commercial tethers I looked at were nylon. I don't think anyone uses polyester webbing for tethers. Jacklines, I tested both. In this case, nylon will stretch too much for all but tiny boats, and polyester too much for larger boats.

As it turns out, it is known that nylon climbing webbing can just barely pass this sort of drop test, but the manufacturers use one grade stronger. 8mm rope can take twice the drop, more times.

Nylon webbing stretches about 7% at 20% BS. That's 3x less than climbing rope, 1/2 nylon doublebraid, and about 2-3x polyester webbing, as I recall.

The answer is probably not the material in the sense of something other than nylon, but rather a change in the weave. But the market is too small. Also, if you loosen the weave, snag and wear resistance drop fast. Sewing might also become a problem.

Interestingly, there have been a few fatalities associated with climbers using spectra for daisy chains, and then taking very short (a few feet) falls. With nylon webbing they could get away with this, but with Spectra, the loads are too great. In this case, there is nothing wrong with spectra--it's lighter--if the climbers understand that there is zero stretch and keep the slack out.

As such, short (work station) tethers can be very low stretch, but as they get longer--certainly 6 feet and over--the value of impact absorption increases.

[UNCIVILIZED]

I gather that in the context of using climbing rope for sailing tethers, it's wise to seize the bitter end of the cordage which exits the knot, to the main body of the tether line. So that the knot's less prone to coming adrift of it's own accord, either in use, or when it's stowed in a locker. And would it be wise to coat/soak said knots with RP25?

[UNCIVILIZED]

Originally Posted by thinwater

Webbing: Tethers, webbing only. Polyester would not pass the drop test, and nylon will with a small safety margin. To my limited knowledge, the commercial tethers I looked at were nylon. I don't think anyone uses polyester webbing for tethers. Jacklines, I tested both. In this case, nylon will stretch too much for all but tiny boats, and polyester too much for larger boats.

As it turns out, it is known that nylon climbing webbing can just barely pass this sort of drop test, but the manufacturers use one grade stronger. 8mm rope can take twice the drop, more times.
Are you speaking of tubular or flat webbing? And in which case(es) specifically?

Nylon webbing stretches about 7% at 20% BS. That's 3x less than climbing rope, 1/2 nylon doublebraid, and about 2-3x polyester webbing, as I recall.

The answer is probably not the material in the sense of something other than nylon, but rather a change in the weave. But the market is too small. Also, if you loosen the weave, snag and wear resistance drop fast. Sewing might also become a problem.

Interestingly, there have been a few fatalities associated with climbers using spectra for daisy chains, and then taking very short (a few feet) falls. With nylon webbing they could get away with this, but with Spectra, the loads are too great. In this case, there is nothing wrong with spectra--it's lighter--if the climbers understand that there is zero stretch and keep the slack out.
Crush injuries of internal vital organs?

As such, short (work station) tethers can be very low stretch, but as they get longer--certainly 6 feet and over--the value of impact absorption increases.

I gather that in the context of using climbing rope for sailing tethers, it's wise to seize the bitter end of the cordage which exits the knot, to the main body of the tether line. So that the knot's less prone to coming adrift of it's own accord, either in use, or when it's stowed in a locker. And would it be wise to coat/soak said knots with RP25?

Also, for those unaware of it, the less stretch there is in your tether, the harder it is on your harness (& you) when you fall. Sometimes including damaging them.

[estarzinger]

Originally Posted by UNCIVILIZED

[COLOR=navy]I gather that in the context of using climbing rope for sailing tethers, . . . . So that the knot's less prone to coming adrift of it's own accord

You will note that Thin is using sewn loops, not knots. He, I guess, has a lot of experience making these. I personally would not be comfortable in my ability to do them reliably. Sewn loops are quite difficult even with machine stitching and these DIY rope ones have to be hand sewn - which has lower consistency/repeat-ability.

Knots are pretty bulky in this application.

But to answer your question - no harm in sewing/whipping/or heat shrink tubing the tail. But also probably not super necessary if you take a minute to look at the tether before you use it - figure 8 knows are pretty quick and easy to 'inspect' with a glance.

On the bigger question . . . I fundamentally dont like/accept the generally used tether/jackline design - which allows people to pretty easily go overboard while tethered and to fall long distances while tethered. If you change the basic design (as I did) so that it does not allow such long and/or overboard falls (which is greatly desirable in its own right) . . . then the need for the severe dynamic drop test is (pretty much) eliminated. I personally question whether the severe dynamic test is really required even with the current broken system designs.

[Benz]

^^ This is my whole point about tethering. There should never be a time when you can go even six feet before fetching up against your tether. All these running systems are a bad design in my book.
Many clip-in spots near centerline, and clipping in as short as possible are my faves. With the daisy chain (mine is nylon--I made it before spectra webbing existed), I can also wrap the end around any convenient member (mooring bitt, the mast itself, a stanchion base) and bring the clip back to one of the loops of the daisy. So even without a pre-fixed clipping loop, I can tie in almost anywhere that need requires.
Super versatile.