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post #11 of 29 Old 04-24-2019
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Re: Tether overload protection

As Mark said, assuming that your sailing course is not actually going offshore, the tether that you bought is probably fine for a sailing course. I would suggest that you get tether that is new and in good condition if you plan to single-hand or go off-shore. I don't know where the $200.oo price came from. That seems to be very high. As other have said, tethers should be closer to $110 to $120. Even West Marine has a double teather for $129.00.

https://www.westmarine.com/buy/west-...4aAqF-EALw_wcB

While I am not a big fan of the concept of making my own tether, structural tube webbing is available from climbing supply places pretty inexpensively and its easy enough to install the shock chord retractors inside the webbing. I agree that it does not seem likely that a private individual can properly stitch the webbing to achieve the required strength.

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post #12 of 29 Old 04-24-2019
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Re: Tether overload protection

Climbing webbing does NOT meet the required strength. Remember that climbers use it doubled, in loops. Additionally, nylon webbing is impossible to sew past about 80% strength because of its stretch. The explanation gets technical, but rest assured, it cannot be done. That leaves you at 3200 pounds. The ISAF requirements is 4500 pounds. It is also doubtful that climbing webbing could pass the ISO sail tether drop test (as a loop, easily, as a sewn tether, marginal).

I'd buy one, and I'm a DIY guy that has tested a lot of stitching. The prices have come down to a reasonable figure.
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post #13 of 29 Old 04-24-2019
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Re: Tether overload protection

Sailrite has a couple videos about sewing webbing, with stress testing, etc.

Another DIY trick might be to line a tubular poly/nylon web with a run of Dyneema...This is how APS makes their's

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Re: Tether overload protection

Quote:
Originally Posted by wymbly1971 View Post
Sailrite has a couple videos about sewing webbing, with stress testing, etc.

Another DIY trick might be to line a tubular poly/nylon web with a run of Dyneema...This is how APS makes their's
No, Not ever. Dynemma is acceptable for jacklines, but NOT for tethers.

The ISAF and ISO standards include a drop test and require some level of shock absorption. There are reasons no commercial tether is made of anything other than nylon.

Try this test. Make a tether out of something non-stretch like Dyneema, tie it to a tree, gather up some slack, and take a run at it. If you leave more than 2 feet of slack you are going to get bruises, and with 4 feet of slack, expect a back injury or cracked ribs.

Tethers must ALWAYS have some stretch.

---

There are two VITAL shortcomings with the Sailrite testing:
1. They tested polyester webbing, which does not stretch. Sewing a material that stretches, like nylon, requires a different method. It's like sewing elastic. A box stitch is not used for this application, so the formula and testing is not valid.
2. Nylon is always bar tacked. Look at ANY climbing equipment. There are engineering reasons for this that have NOTHING to do with economy.
(I used to be in the industry and have tested sewn nylon--I'm not guessing or reading off the net)

They very wisely stopped selling the harness and tether kits. They did not meet any of the required standards. They are sailmakers, not structural equipment fabricators.

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post #15 of 29 Old 04-25-2019
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Re: Tether overload protection

Quote:
Originally Posted by pdqaltair View Post
No, Not ever. Dynemma is acceptable for jacklines, but NOT for tethers.

The ISAF and ISO standards include a drop test and require some level of shock absorption. There are reasons no commercial tether is made of anything other than nylon.

Try this test. Make a tether out of something non-stretch like Dyneema, tie it to a tree, gather up some slack, and take a run at it. If you leave more than 2 feet of slack you are going to get bruises, and with 4 feet of slack, expect a back injury or cracked ribs.

Tethers must ALWAYS have some stretch.

---

There are two VITAL shortcomings with the Sailrite testing:
1. They tested polyester webbing, which does not stretch. Sewing a material that stretches, like nylon, requires a different method. It's like sewing elastic. A box stitch is not used for this application, so the formula and testing is not valid.
2. Nylon is always bar tacked. Look at ANY climbing equipment. There are engineering reasons for this that have NOTHING to do with economy.
(I used to be in the industry and have tested sewn nylon--I'm not guessing or reading off the net)

They very wisely stopped selling the harness and tether kits. They did not meet any of the required standards. They are sailmakers, not structural equipment fabricators.
Thank you for posting this. I think most of us come here to be helpful and to learn from those who know more about a subject than we do. I had always assumed that if i ever made a tether it would be a nylon tube over a dyneema core with the dyneema spliced to the hardware and with a shock chord in the tube acting as a retracter. In my ignorance, it never occurred to me that it was possible that there could be too little stretch to a tether. I really appreciate your explanation. Live and learn.

Reading that, it sounds like if someone had to make their own tether, the core would want to be something like 3/8" diameter 3-strand polyester or even nylon spliced to the hardware with the tubing reducing slip potential and providing a UV screen rather than a structural component. On the other hand, the case that you clearly make suggests that making your own tether is simply a bad idea.

For what it is worth, I use an 11 mm kevlar cored line as my jacklines and hook onto the windward line thinking that they would prevent me from making it over the leeward toerail. (So far they have) It sounds like that isn't a great idea either.

Jeff
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post #16 of 29 Old 04-25-2019 Thread Starter
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Re: Tether overload protection

Thanks for all of the thoughtful responses.

I bought this harness because I was possibly going to be on a TAG boat with only a few days' notice. The chandlery was completely out of 3-point tethers due to the recent boat show, so I resorted to the consignment store. I didn't end up on the TAG boat, but now I have this tether which seems to have good hardware, is not faded, but doesn't have the stretch left in the longer leg. However, I couldn't find any broken threads on it. I'm happy to replace the entire webbing if that is the right course to take. The CPM class will go out the Golden Gate to the Farallons, but not if the winds exceed 30 knots. I am going to purchase a new tether online as well. But in the meantime, I am trying to assess this one.

I appreciate the link to the $100 tether. Looks good! I'll probably buy it.

I'll post pics as soon as I can. (Off to work right now.)
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post #17 of 29 Old 04-25-2019
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Re: Tether overload protection

Here are a few links you may find helpful:

https://rockandice.com/climbing-gear...mbing-webbing/
https://www.rei.com/blog/climb/when-...-climbing-gear
https://www.blackdiamondequipment.co...uickdraws.html

Most climbing slings are rated to 22 kN which is about 5000 Lbs.

I would avoid dyneema slings as they do not have good abrasion resistance and tests have shown that knotting them significantly reduces breaking strength.

I suggest you look into the Personal Anchor Systems (PAS) used by rock climbers. I use a Metolius Ultimate Daisy Chain as my PAS: (NOT to be confused with the sewn daisy chains that are used for aid climbing.)
https://www.metoliusclimbing.com/ultimate_daisy.html
Metolius also makes other models as do other manufacturers:
https://www.metoliusclimbing.com/pas...or_system.html
https://www.metoliusclimbing.com/alp...or_system.html

These consist of a series of sewn links formed up into a chain which a climber then girth hitches (Lark's head to sailors) onto their harness. The chain links allow the climber to vary the length of the PAS by attaching to different links and to add redundancy into their anchor setup by attaching different points in the chain to different points of protection.
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post #18 of 29 Old 04-25-2019 Thread Starter
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Re: Tether overload protection

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Originally Posted by MarkofSeaLife View Post
Oh, I can answer this!

In general: pay the least for gear while you are doing lessons. Because it maybe the last time you go sailing.
If you do go crewing after your course your skipper will have tethers.
If you buy your own boat then you need to take a but more care.

Tethers will degrade (mostly) by 3 things:
UV
Abrasion
Impact

Like a seatbelt 1 car crash and you should replace it.

Unless you buy a tether new you don't know if it's been left in the sun for months, or if it's been stressed.
So when you buy your own boat you should upgrade to a new one but this one is fine while you're learning.

As a tip: Wichard are very good but are expensive. There's gotta be more economical but still safe brands 😊
I already own a boat, so I hope it's not my last time sailing when I do my next level of classes.

The Wichard tether was the only one at the consignment store that looked at all worthy. The others were only 2 point tethers, and faded, so generally looked like something I wouldn't want to trust my life to.

I'm not attached to the brand, except to try to improve the one I have by buying new webbing for it, if necessary.

I am going to buy a brand new harness, and probably won't buy a Wichard because there are others that will do the job just fine.

After watching a YouTube video on the testing of tethers, I'm fairly certain that if I fall off the boat attached to a tether, I'd better have a sharp rigging knife at the ready so I can cut myself free. It looked like a sure-fire way to drown. I'm assuming the only way a tether would save my life is to keep me on the boat in the first place. Barring that, the skipper had better be really good at stopping the boat on a dime or I'll drown at any boat speed above 2 knots.

But, at any rate, the tether is required for Coastal Passagemaking so I'm getting it.

On my own boat, I need to rig the jack lines so I won't go overboard. If I'm single-handed, the skipper will be me.

I'm going to order that $100 tether now...
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post #19 of 29 Old 04-26-2019
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Re: Tether overload protection

If you own your own boat. No problem owning a second harness for guests.

I can't believe they won't go to the Farallons above 30 knots. Wimps.

I grew up in the bay area and lived in San Diego until recently. I remember racing in SD and the owner considering taking down the spinnaker because it was blowing around 20.

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post #20 of 29 Old 04-26-2019 Thread Starter
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Re: Tether overload protection

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Originally Posted by jephotog View Post
If you own your own boat. No problem owning a second harness for guests.

I can't believe they won't go to the Farallons above 30 knots. Wimps.
I suspect they got tired of all us newbies getting seasick.

Yes, I need to have spare tethers on my own boat, but it'll probably be a couple of years before I point her out the Gate.
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