The Offshore Voyaging Reference Site

The Right Tethers To Keep Us Aboard—Part 2, Construction and Hardware

In the last chapter, I wrote about the two different types of tethers Phyllis and I use on Morgan’s Cloud. In this chapter I will cover how we build each type. Let’s start off with the hardware we use:

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Stein Varjord

Hi John.

Thanks for a nice and important post. I’m convinced that the system you have developed now is a very much better one than any i have ever seen. Actually, none of the many hundred boats I’ve sailed have a system that is even decent. Most have harness systems I think may be worse than no harness at all. As I’ve ranted about earlier: False safety…

One tiny detail might be of interest. As an alternative to the Wichard snap shackle you show, the same company makes very similar snap shackles meant for high load release. There’s mainly one difference: The hinge is moved further out, close to where the load will be hanging. This way the pin has way less load an is easy to release. These also have a hole for releasing with a spike. I’ve hand released bigger versions of these with a load of more than two tonnes. Maybe these are better for the man end of the tether?

My cat is easier, but I’ll now go through all these issues with a critical mind and adapt it to your system. I guess I won’t be the only one here with that plan. I hope all reading here will also spread the conclusions made in this book. Close to every harness system afloat is dangerously flawed and must be changed. Few cruisers will discover this fact by themselves, until a serious accident happens.


I know the high-load-release shackles Stein mentions under the name “Trigger shackle”. They are intended for spinnaker sheets, were originally made by Tylaska (still are) but the patent ran out so they have been available from Wichard for a number of years as well.
With no load, they can be opened with a strong finger but for higher load a “fid” is available (or a marlspieker – German term – on a sailor’s knife can be used).
I have a few (from Wichard) and find that they become much harder to operate with a finger after they have become a little rusty.
Wichard made one from Titanium but it’s not listed on their web site at them moment. These may corrode less and are lighter.

The normal snap shackles you use have a small “key ring” to connect the pin to the lanyard. When you pull hard, that key ring will unwind and separate from the pin. I am sure that is what will happen when someone is being dragged or held under water and is trying to pull the pin in an emergency. When the key-ring is gone, there is no way to open the shackle other than with a pair of pliers. I have had this happen several times with pelican hooks on our railing but not (so far) with Wichard snap shackles.

Maybe this:
or this:
is the ideal solution (no key-ring to unwind, opens under high load, doesn’t require a tool)?


Petal makes some interesting stuff for the “via feratta ” in Italy- vertical trails with fixed iron safety rails into which one clips. A lot of similarities exist with the physics we are discussing for lifelines, and their solution may apply well.
This link is to a double clip, with the sort of easy binders we like, similar to King, but, indeed, Petzl is an even more respected name among climbers. Absolutely the tops. They have others, and one which I have copied in my own tether construction, I will describe below. But first, Petzl:

So, my adaption of the via ferata concept goes like this: starting with the harness connection, I used the same fixed Wichard snap shackle-it’s ideal. I use a girth high with about 3 meters of line ( I made this a while ago, and used 7mm perlon cord, which is not dynamic, but will be switching out to 8 DCR shortly) and then at the ends, attached fixed eye biners with a ring bend, and a sewn tail, as you have done with the estar.
The point of the girth hitch at the harness attachment was to create some dynamic give- as the load came on the system, the girth hitch lets the line slide through, attenuating the load over time.
I will be making some new tethers this spring using some of the concepts from this series ( which is really a useful bit of thinking, I must say)
Using the 8mm DCR, the Wichard snap and two easy binders ( I’ll probably get the Petzls)
The key additional concept here it the line movement through the harness attachment point. Petzl at one time made a unit precisely for that function, and may still. I am search for that, but have not fount (re-found) it yet.

mark goldsmith

Marc- no, that’s an interesting bit, but I’m remembering an older piece, with a designed loop to control release/ slide, I think the adjust is static when loaded

Henrik Johnsen

There are many good points regarding a well functional and safe tether system in the article, but I don´t agree on the use of the Wichard shackle.
In my job as a rescue man doing Airborne (helicopter) rescue missions, we only trust Twist-Lock carabiner. They have a two-step procedure to open to prevent any accidental opening, which easily could result in fatal consequences.
I don´t think Wichard shackles will be the right thing in a tether system because it can open accidental, with a catastrophic result.


The Wichards are right because they are more able to open under load. A twist lock will not do so. And, John’s thoughts on a sharp knife at hand are right on, too!


John – Thanks for this great article.
You have said that you don’t have a real solution for staying inside the lifelines when working on the bow. Would you consider the Petzl Connect Adjust Lanyard, used reversed, as a possible solution to allow shortening the lanyard as you move forward?


Stein Varjord

Hi Roger.

I guess John has thoughts on this too, but what I think is that adjustable tethers mostly are risky. An essential property of this harness system is that we know for sure how far we can fall anywhere on the boat. It’s tested and adjusted to the exactly right position. Shorter gives no extra safety and longer gives definitive danger.

If we have adjustment, we’ll tend to leave it a bit longer than we need. Especially when the going gets tough, we tend to make wrong judgements. If I really needed a longer reach somewhere, now and then, an adjustable tether might work, but maybe it’s just as good to skip the tether and be properly aware that you’re doing something dangerous. If I have a tether attached, even if I’m aware that it’s bad design, it still makes me feel safer and act differently. Humans have emotions, which is very nice, but it also messes with our judgements…. and we don’t notice that until it’s too late. 🙂

Eric Klem

Hi John,

Thanks for the well thought-out series on this. Is there a reason why you don’t use the Kong Tango on the person end as well? I agree with your thinking on the inability to release a snap shackle under load so I assume the reason must be usability? I have never used a Kong Tango and was planning to when making up new tethers soon.


Dick Stevenson

Hi Eric & John,
One area to watch out for with the KT and carabiners of their design (on the person end) is the square notch on the fixed end looping over the top. Things that are small can get jammed in it and be difficult to extricate from: think metal rings that are sometimes on harnesses/lifevests. If the ring is about the same size as the notch, you have the makings for a jam and or damage to the notch. If the pressure direction is right and strong enough, even webbing can be hard to lift out of the notch and then out of the fixed looped-over section.
I don’t see them as good for the person end of tethers for the above concerns as well as, when under pressure, you may be able to open the carabiner with ease, but you still have to generate slack and then move the biner over to actually effect release.
My best, Dick Stevenson, s/v Alchemy

Drew Frye

I’ve used the Kango on the person end for 6 years. Never a jam or a hint of one. They are very fast an easy with one hand, and I do not have to confirm that they are closed (fabric can jam a snap-shackle not quite closed). As for quick-release, remember that World Sailing does not require a release of any type–this is an area where people simply disagree. For my part, I find a Tango much easier to detach/re-attach should I need to disentangle my self while working (we all get on the wrong side of something once in a while), and this is more important to me that the tiny potential of a situation where detaching under high load is required. I am primarily a single hander; you would have to try hard to convince me that detaching is ever going to be better. Even hanging, it is not that difficult for me to generate enough slack to unhook–a climber thing, perhaps. If the boat were inverted (that is a risk for performance cats, but not cruising cats), there is no reason to believe the tether is under tension. Catamarans do not have the bow wave drowning machine that monohulls have (the bow wave is small and we don’t heel). In fact, the greatest risk is getting thrown in front of the boat, if you stuff a bow and the boat stops–this is easily prevented by terminating the jacklines >6 feet back. This won’t happen on a monohull. Finally, I do not wear crotch straps, and without them, anyone can worm out of a harness in 20 seconds if they put their hands over their head, and relax. I have shoulders (can do 20 pull-ups), but when relaxed they get smaller than the harness. Thus, if there is too much tension to kip up and release the shackle, I can worm out; one or the other will always work.

In the past I had a snap shackle on the person end of the tether–I replaced them with Tangos. But this is a personal choice. As I pointed out, and contrary to the forum mantra, World Sailing does not require or even recommend any release. Just sayin’.

However, I can think of other boats and other sailing styles where I would prefer a snap shackle (crew, monohull), so I am not preaching. I believe the answer “depends,” just as John has what I believe are intelligent jackline locations that are quite different from mine. Different boats.

Dick Stevenson

Hi Drew,
Thanks for the response. Good to hear your experienceand ,as always, well thought out and well put. Dick

Rob Gill

Second that Dick, love your reasoning Drew.

Eric Klem

Hi All,

Thanks for the feedback on this. I think that I will pick up a few KT’s and try them on both ends to see how they work for me.


Eric Klem

Hi John,

As we finish up our season here I thought that I should report back on trying the Kong Tango at the harness end of the tether. We switched to your system of leaving the tethers in place as well this summer so I don’t have a perfect 1 to 1 comparison. The short answer is that I really like the KT and will continue to use it until something better comes along.

Overall, the KT is my favorite attachment method I have come across. It is very easy to use but also secure. I like the light weight of it. Also, the ability to get different colors is great, we have 3 different lengths of tether and this makes it easy to tell them apart when putting them back on deck after storage below.

The only thing that I haven’t liked is the length of it. If you use a knot to attach the tether, shorter crewmembers can end up with this sitting uncomfortably in their groin area when seated. This problem has been largely solved for us by going to spliced 3 strand nylon (we only have 1 tether on a hardpoint and I am willing to make this compromise). The other item that I wonder about is how long the KT’s will last in the marine environment, so far there have been no signs of corrosion and I can’t see anywhere that the anodizing has been damaged but it has only been a single season.



Hi John.I would like to have some information about the sewing of your tether, as seen in the first chapter (picture in the basement of the mast). You say “read the linked post for the details” but I have not found anything…
(PS excuse my poor english, I’m french)

lars Erik Karlsen

Hi John
Thank you for useful and informative articles about tethers and center jacklines. I will try to adopt this on my own boat before season starts.
best regards
Lars Erik
Sula Bassana

George Woodward

Hello John
To what extent do you factor in the stretch percentage when determining tether length?
I am adopting your system ( put a high structural arch just behind the sprayhood to provide a high fixed point for the cockpit and make it impossible to stand under the arch)
For example a 12ft beam suggests a 5ft tether to end one foot before the lifelines. But 30% stretch on a dynamic rope to 6.5ft will go beyond the lifelines. This gets worse on a bigger beam. I guess the same would apply to a non stretch tether relying on the central jackline for absorbing shock load.
I think I should just buy some line and try the variables!

Bruce Bayne

What material do you use to make the crown sinnet lanyard?


Bruce Bayne


Thank you! I just purchased several Wichard snap shackles, #2471, as per the link you have in this article. They are 50mm long and looked a bit small for the job. When I tried to tie an estar knot in one I found that the eye was too small to allow 2 passes of my 9mm DCR tether. Are the snap shackles you are using 50mm long or are they the larger 70mm (#2472) model?


Bruce Bayne

I also found that the Pam Narrow 1″ webbing doesn’t fit either, no matter how hard I tried to distort it.

Bruce Bayne


It happens. 🙂 A minor blip in an otherwise excellent website.

I got a very good deal on the 2471’s on eBay, and the seller doesn’t take returns. I will be advertising them on Craig’s List to see if I can sell them, unless anyone here would like to contact me on purchasing some 2471’s cheap. I have seven.

Also, the picture is of the 2471 as well. Not that the picture will change much as the two shackles look the same, but the name of the picture, if you download it, is “A-WICHARD-2471-0002.jpg”. Just trying to be thorough to go along with my OCD. 🙂

Thank you for answering my question and fixing the website so quickly. Enjoy your vacation!

Jordan Bettis

This article is really good and excellent points in the whole series.

I have two thoughts: Why not use carbiners at both ends of the tethers? They’re less expensive than those snap shackles, and, as you said, the snap shackle probably won’t release under load anyway. And on a monohull, even if the boat is rolled, it’d still be best to stay attached to the boat rather than float free. I recall a boat that got rolled in the Pacific a while back, the only fatality was the helmsman who was clipped to the binnacle. It broke and he was lost overboard.

I’ve quit using the inflatable PFD/harness combination and have switched to a straight pfd + a rock climbing harness. A rock climbing harness holds you with wide thigh straps instead of those horrible ridiculous crotch straps they’re retrofitting onto the sailing harness. And the clip is right above your body’s center of gravity, so you hang upright but not from your armpits.

Jordan Bettis

Thanks for the reply John. Yeah the harness is hard to get out of. That’s a pain when I have to pee.

In the scenerio you describe in your other post, with snotty weather around, I would be wearing my mustang sentinel suit and a harness already, down below. Or probably even resting in the cockpit. But I mostly singlehand so I’m used to having to be in the cockpit within seconds of something changing.

Richard Stevenson

Hi John and all,
Apparently, there was a sailing death last year attributable, in part, to a tether shackle/carabiner (pictures make it similar in looks to the Kong and others of that design) opening when it was loaded “out of line”. The “Safety Lesson” was written as:
To prevent the strength of a safety harness tether becoming compromised in-service due to lateral loading on the tether hook, the method used to anchor the end of the tether to the vessel should be arranged to ensure that the tether hook cannot become entangled with deck fittings or other equipment.
Initial findings can be had at
and include pictures and a diagram, but do not comment on the design nor give the manufacturer.
My best, Dick Stevenson, s/v Alchemy


Hi Richard

Practical sailor has a article on the same subject (same pictures, even). But they also tested the case where the tether fouls the clip closing mechanism leading to low (<300lb) failure loads.

I understand the vast difference of strength between an open and closed clip but the use of flat stock in those clip seems like a fundamentally flawed design. Look at climbing carabiner in cast aluminium like the Kong tango. Open gate resistance is better than the 300 pound tested by practical sailor and the 3D profile must give better resistance to lateral force.
found through

Richard Stevenson

Hi Mathieu,
My PS has yet to catch up with me, but I would suspect it would have a good deal more info than the very brief report I cited. Interesting that the pictures are the same. Agree on the use of flat stock. It is my understanding that an open-gate scenario is very unlikely (in an in-line load), but that a wrap-around-side-pull scenario is one that could occur fairly easily for those that might have slack in their jacklines or who have them go around corners. There are likely other scenarios, as well, to watch out for.
My best, Dick Stevenson, s/v Alchemy

Marc Dacey

An interesting report on shackles/carabiners from Drew Frye and Daryll Nicholson in this morning’s Practical Sailor e-blast:



Thank you for the great series. I am going to implement your system but why not have a sewn loop at the deck end of the tether (with jackstay running though it) rather than the Kong. There may be some chafe which means more frequent renewals of the webbing but on the other hand, there is less hardware banging on the deck, it’s more cost effective and it eliminates the temptation for the crew to unclip that end.

Stein Varjord

Hi Kean.
I agree that this is a very interesting and important series, and I think every boat should implement systems based on this knowledge, since most tether systems I’ve come across (a large number), are dangerous because they don’t do what they’re supposed to do. They give a false feeling of safety. That means they make our tasks more dangerous than if we wear no tether, which makes us aware of the danger.

A sewn loop has properties I like a lot. Simple, light, fail proof, cheap, silent, etc. Still I wonder if it might give too much friction and become a hassle when moving. It might be better to have a small steel ring sliding on the jack stay. It’s light and fail proof enough. Or perhaps a plastic thimble spliced in would do the same job. Plastic isn’t strong, but the strength is in the rope. The only time it’s loaded is what we fall, so we can then just change the thimble, if needed.

The main reason for having a Kong Tango there is to be able to take the tethers away when in a harbour, to avoid sun damage and keep a tidy deck. I’ve been pondering this a bit, and I’ve come to think that I prefer to keep the tethers and jack stays as one system that gets removed together. The jack stays are also subjected to sun deterioration and are also deck clutter. I also have a feeling that the procedure with removing and remounting them is a good routine check for weaknesses. This system might on some boats even be less work than removing each tether and leaving the jackline. Either way not noticeably more, if the attachment points are made easy to use.


Thanks for the comments John and Stein. I’m going to have the tethers made with a sewn loop on the deck side and be conservative on the length. If I have issues with friction or flexibility, I can then easily cow hitch the Kong Tango on the deck end.

David B. Zaharik

Hi John,

I have commented previously and find this subject dear to my heart having survived a MOB and swam for my life in 14 C water for almost 4 hours without a lifejacket…

I know you are somewhat familiar with the Boreal and thought I could ask your opinion (only that, no legal attachments, blame, liability attached here) on a suggestion to a system to rig on the Boreal to maintain centre line integrity.

As you may know there are hard points in the cockpit, so that is straight forward. However, it’s the transit out of the cockpit forward I am struggling with… The only system that I have seen runs jacklines from the hand holds on either side of the doghouse to the base of the mast (or it might have been to the granny bars.) Then of course there will be one line from the mast to the bow. Not ideal, but can you think of a better solution?

With the centre point mainsheet attachment on the top of the dog house and the subsequent sheeting and block system, attaching to the centre is not possible.

Like you, I am a firm believer; evangelical fundamental believer, in staying ON BOARD, any thought or rationalization otherwise is delusional. You go over, you die. True in my incident I didn’t, (in case anyone was wondering), but I was swimming in totally flat calm waters in the protection of Georgia Strait south of Vancouver. The ocean is massively different as you have clearly explained.

David B. Zaharik

Thank you John,

Ya…. I think I am too late to add pad eyes without marring the finish. I’ll ask. The hand rails may work better than I thought and keep the tethers short enough. Thanks again.

David B. Zaharik

Hi John,

I went to a local marine shop who have staff that are off-shore racers to look at the Kong Tango. Have you ever experienced any sort of deterioration of internal parts due to dissimilar metals or interior springs rusting etc.? What about it scraping the paint?

They also had a carabiner by MakeFast out of the UK which has a double lock, operated by one hand, plastic coated and this year MakeFast have a new model coming out. The mechanism ‘seems’ much more robust than the Kong Tango but I am sure the Kong Tango is certified rigorously… you or Drew Frey might want to contact them to see this new version. It is a bit heavier than the Kong Tango but I am concerned with protecting the finish on the painted aluminum deck and cabin top.

I have a spec sheet from MakeFast but the new unit won’t be available until year end. I’m not sure what the difference is between the new and the present one.

David B. Zaharik

Very good, thank you John. I really did like the weight of the Kong and funny enough, I mentioned using Boeshield … that stuff is amazing!


Tracy Tullier

John, you mentioned that you attached your aft deck DCR tether to your boom gallows with a cow hitch. Did you make a knot or eye splice in the end of the DCR tether to do this? Or perhaps loop around with a figure 8 with follow through. Did you find one particular way was more secure using the DCR?
PS Thanks for this great ebook!
Tracy on Contessa

Tracy Tullier

Thanks, John! That’s what I figured once I found the picture showing this on a previous chapter. Making progress on designing and implementing a system that weeks for out boat. Biggest issue for us is the tether lengths especially at the transition from the cockpit to the mid-deck jacklines and not violating the one foot from the toe rail rule. (Our cockpit coaming is a little more than one foot from the toe rail in our csy 44

Tracy Tullier SY Contessa

Also I also feel that combination with netting in this traditional area would make this much safer

wayne armstrong

I have been using 7/16 New England Rope yacht braid polyester with a double braid splice on each end for my tethers. 6,000 # breaking strength with a similar stretch characteristics to climbing rope. Recently an engineer / climbing buddy commented that he would not trust my eye splice over a proper knot. So as a test I made a new 6′ tether and attached it to the base of a cedar tree with a lifting strap and attached the other end to the hitch of my 8,000# diesel pickup, the line finally parted in the middle of the tether after six pull tests leaving approximately 2′ of slack before coming up hard on the truck hitch and tree. The eye splices did not fail. Is there a reason why I should not use this rope for a tether? I Use Black Diamond twist lock carabiners and to to keep my tether away from the opening end I slide thick rubber grommets onto the carabiner with the tether in-between. The grommets also keep the hinge end of the carabiner from striking the deck when being dragged.

Alain Côté

Hi John,
I am finally setting up my MOB prevention system on my Boréal 47, Snowstar. One question on the DCR. My quick research has shown that there are three kinds: single, half and twin. Can you tell me which one you use?

Thanks, best regards, and congratulations on a great chapter!


Travis Ruse

I am starting to put together my first tethers as per your model and I have a basic question. You talk about DCR not being splice friendly but you have stitched down your knot. I’m new to stitching and would love to get some directions on how to best do this. Additionally any advice on resources for stitching in general? Thanks!

Terence Thatcher

We changed some of our tethers to DCR, using Wichard Snap shackles on person end. Two questions: need we really be concerned with the split ring to which we attach our lanyard? If so, what is the solution? And if we use DCR for tethers, can I use dyneema for the centerline jacklines? I stupidly used polyester double braid, so now I have too much stretch in the system.

Bill Attwood

Hi John
Picking up on an old topic, corrosion in aluminium carabiners. While reading some stuff on climbing I came across advice to wash alu carabiners in fresh water after climbing on sea cliffs and this prompted me to research further on the Kong Tango. It might be a good idea to advise people using this system of tethers to follow the advice of the climbing community. There’s quite a good overview at “”.
Yours aye

Erik Williams

Hi John. I’ve been an avid climber for decades. Climbing gear of a variety of types finds it’s way aboard my boat frequently. I inspect it (biners in particular) quite carefully on a regular basis, and use it in all sorts of applications. That said, Alu gear is not used in lifeline rigging on my vessel, and the tethers are all made with stainless. I’ve seen the corrosion first hand. It’s a real potential problem, IMO. Any Alu gear on board is retired from climbing duty. Period.
I use slings and various ascenders and their ilk all the time, but I’d never trust any of it on the cliffs again.

Michael Hiscock

FYI. I purchased some 8.2mm DCR and placed an Estar knot on each end. I then sent it in to a local test shop. It failed at the knot with a pull of 3247 pounds.

Michael Jack

John, I haven’t seen this question in the comments so I hope I am not repeating but one thing I don’t understand about your construction is why you have a shackle at all in the deck end? Why not just sew a bigger loop in the tether and put the jackline through that (well for the webbing tethers at least)?

Michael Jack

Thanks, John and makes sense. After I posted this question I also read the linked article at practical sailor about making your own tethers and jacklines and, if I understood correctly, a bigger loop puts more pressure on the inside (closest to the loop) stitching. At least that was my interpretation.

Michael Jack

Thanks, John. And indeed after re-reading I see that now (it usually takes me 5 reads of anything to really get it).

Brad Manter

Hello John,
I re-read this and still could not find an answer to this question: why can’t I simply use a DCR tether to attach to jacklines as well as hard points? Maybe I missed that detail? Many thanks, Brad.