Safety Tether

[afw]

The commercial safety tethers seem always to be made of webbing, with
about 6000 lb. breaking strength. I am thinking of making some tethers out
of 1/2-inch three-strand nylon, which has about the same breaking strength.
The reason that I am planning to use rope rather than webbing is that I trust
my splicing ability more than my sewing ability.

I will use a snap shackle at the harness end, just as do the high-end
commercial tethers. The tethers will be double legged, with one leg
being 3 feet long and the other six. At the end of each leg, I will use
an eye-splice to attach a locking safety hook.

The rope will pass through the attachment eye on the snap shackle.
Instead of using a splice, I am thinking of seizing the bight of rope together
at the shackle.

How does the strength of such a seizing compare with that on an eye splice?

[osteoderm]

Ah, it took me a moment to understand what you're getting at. As i envision it, if the seizing where to fail, the line would run through the attachment and fetch up at the end of one leg or the other; you'd be at the end of a single 9' length. A properly applied seizing ought to work, but if one of the eysplices ends/clips were to be lost for any reason, you may well be relying on the seizing for your life. See Brion's warning re: inner/outer bobstays seized in such a fashion in the Apprentice.
i can understand trusting your splicing over your sewing, but why trust your life to either? It sounds like a case of thrift (which i would otherwise heartily support), but quality commercial safety tethers are pretty cheap peace of mind at any cost.
One home-brew solution i've often trusted are common rock-climbing daisychains. These are continuous loops of flat sewn webbing, sewn together every 3 inches or so, making a long chain of little loops. They come in various lengths. For work aloft, i have two, about 2' and 4', cow-hitched to my harness, with burly locking carabiners cow-hitched onto the ends. All the loops make it easy to adjust the tethers to any required length. i've spent many many hours up both rock walls and masts hanging from such tethers and completely trust them. They're cheap enough and available enough (at climbing shops) to simply discard and replace at the first sign of wear.

[Brian Duff]

I would use a tether like you suggested, and I would rather trust my life to one of my splices than to some machine or commercial assembly line 'seam-ster'
If you handed me a 1/2 three strand tether with saftey locking clips at each end and a cow hitch in the middle, instead of that snapshackle and seizing. That way who ever is wearing it can adjust the lengths as they see fit.
Splice carfully, and use an extra set of tucks maybe too....

[Ian McColgin]

Thinking of tethers from a different point of view:

The reasons for double legged tethers are generally that they give some choise of movement and that they make it possible to clip past lifeline stauncheons without disconnecting completely.

The double legged lifeline is a bit of extra tangle and working from the longer lead, while it can give you a bit more access from the weather rail, can give you a long way to fall before catching up.

On my boats, I found double legged tethers unnecessary if proper jack lines, one for each side, were rigged bow to stern. With such jacks, a tether that's about long enough that one can just grab the far end will hold the far 'biner off the deck a tad as you work your way foreward or aft and, counting jackline stretch and assuming intelligent placement, will give access to the masts from either side and pretty much all of the foredeck.

You may have to train for going forweard on the lee rail for those rare times when you must work on that side. Many folk find it emotionally uncomfortable, though at an extreme heal it's actually safer and more comfortable to lean into the boat rather then bending against the weather lifelines.

Even with the end of the tether within reach, many consider it a safety feature to have a 'biner at the chest as well, in case one must disconnect in a hurry, like the boat's sinking. With the end within reach, this is not a real worry. With a figure 8 type harness, it's comfortable to have the chest end of the tether attached to one D ring or sholder loop and pass through the other, a plain loop around both for security, and on out. That way the harness is loose unless there's load on the tether. If the harness is a bit large for the wearer, a 'biner at the near end will foul, maybe even open, as it runs against the loop.

For these reasons, I've moved away from double legged tethers. But, different boats, different long splices. A tether you use is better than someone else's hypothetically better (for them) tether that you don't like.

G'luck

Ian

[Dan Lehman]

Originally Posted by afw

The commercial safety tethers seem always to be made of webbing, with
about 6000 lb. breaking strength. I am thinking of making some tethers out
of 1/2-inch three-strand nylon, which has about the same breaking strength.
\...\
The tethers will be double legged, with one leg being 3 feet long and the other six.
\...\
The rope will pass through the attachment eye on the snap shackle.
Instead of using a splice, I am thinking of seizing the bight of rope together
at the shackle. /.../

Alternatively, for greater flexibility in positioning the harness attachment point,
and even the use of the device, one might fix the harness snap into some hi-mod
7-9mm "Prusik" cord and attach to the half-inch tether with a Prusik Hitch.

--dl*
====

[Don Ferrell]

Stay with the boat:
When sailing short handed (one person on watch) on my Cascade 29 with a beam of 8’ I rig a tether with a snap shackle each side from a strong point forward of the shrouds long enough to reach a swim ladder at the transom, to allow a person who is overboard to disable the steering vane to slow or stop the boat and climb back aboard via the boarding ladder mounted there. A person overboard forward of the mast with a typical 6’ tether and bow to stern static line will be held to the side of the boat by the pressure of the water with no way to slow the boat and get aboard. A static cord on the centerline with a short tether to prevent falling overboard would be so restrictive that it would not be used all the time. I’m interested in hearing any comments about this.

Recover:
In an earlier life I was a firefighter stationed on a fireboat. We were often called to recover a floating body, usually several days dead. After my first experience with this delight I sewed up a canvas stretcher, about 7’ square, the near edge fastened to the rail, the far edge had a pole in a wide hem with a pole fastened to each end. It was then easy to scoop the body up and hold it against the side of the boat, out of the water, while we returned to the dock where we would turn the body over to the police. This same overboard recovery system should work on a sailboat using a sail for the scoop.

[Auspicious]

Originally Posted by Ian McColgin

On my boats, I found double legged tethers unnecessary if proper jack lines, one for each side, were rigged bow to stern. With such jacks, a tether that's about long enough that one can just grab the far end will hold the far 'biner off the deck a tad as you work your way foreward or aft and, counting jackline stretch and assuming intelligent placement, will give access to the masts from either side and pretty much all of the foredeck.

Another thought, with a boat rigged much as Ian describes. My jacklines run fore and aft, tight, on both sides outside the shrouds. I usually clip on with the short, 1m leg of my tether when going forward. If I will be working at the mast, I clip the 2m leg on and wrap the 1m leg around the mast. In the cockpit, the 2m leg gives me access to the entire cockpit without having to move my attachment point. It also lets me clip the 1m leg on to a jackline before unclipping the 2m leg from a cockpit hardpoint.

sail fast, dave

[Brion Toss]

As the above responses indicate, there are a lot of options for lifeline tethers, so many that I believe we have bumped the original question: webbing vs. 3-strand. As I understand it, webbing is the dominant material for this application because it folds flat so easily, and doesn't stiffen or hockle. Rope is handy, by contrast, when you have to run over a sheave. Different tools for different jobs. If I were going to use rope for a tether, I'd use the most flexy type --- single-braid --- and Brummel it at the ring ( a Ring Hitch is too bulky, too snag-prone). And I'd make it 2-legged, to lengths I prefer; I don't want someone messing with my gear.
As for length, the shorter the better. I have read too many reports of people drowning at the end of long tethers, which just happened to be long enough for them to fall over the lifelines and into the water. High enough lifelines and somewhat shorter tethers will help, and Ian seems to have something like that, but even with falling overboard prevented, I want the shortest possible potential fetch-up at any moment, which for me means chest-high jacklines. It also happens to mean material preferably stronger than 6,000lbs, which is a scant minimum in a shock load, particularly with wear factored in.
As for the awkwardness of clipping and unclipping, I certainly understand the attraction of a free run fore-and-aft; I just see the midship interruption as an entirely acceptable bother at worst, so of like seatbelts, and a distinct feature in fact, as it limits how far you can wash along the deck. And chest-high jacklines make great lifelines on their own, highest just where you are most vulnerable to going over: in the middle of the boat. I sometimes rig and use them even if I am not wearing a harness.
Fair leads,
Brion Toss

[Bob Pingel]

Brion-

Can you share some details on the implementation of your chest high jackline setup?

I am assuming chest high amidship, coming down to deck in a traditional manner fore and aft? Some attached the shrouds?

What is your prefered material for this setup?

Thanks,

Bob Pingel

[Dan Lehman]

Originally Posted by Brion Toss

As the above responses indicate, there are a lot of options for lifeline tethers, so many that I believe we have bumped the original question: webbing vs. 3-strand. ...
As for length, the shorter the better.
It also happens to mean material preferably stronger than 6,000lbs, which is a scant minimum in a shock load,

I'm surprised I didn't way back remark at the focus on strength, which I think is quite
misguided: the BODY cannot take much more than a ton, so strength beyond that is
all academic.
As for shock loads, that is a factor depending upon the material choice: taking typically
static webbing ensures higher shock, less energy absorption; taking typically elastic
(hard- not soft-) laid rope will lessen impact forces. There is some evidence in lanyards
used in caving, e.g., of the energy absorption of a Strangle Noose hitch (as compared
with a splice); but if a knot's bulk is an issue, well, just rely on material stretch.
Another aspect could be vulnerability to cutting? --rope is usually better, here.

.:. Seems like a decent, 7/16", half-inch firmly laid nylon rope should work fine,
spliced or seized or tied.

--dl*
====