The Offshore Voyaging Reference Site

Time to Stop Using And Selling Tethers with Gibb-style Hooks

Many of you will be aware of the recent tragic fatality on one of the Clipper Ventures boats. For those who have not heard the story, here’s an excerpt from the official statement by the company:

Simon, 60, from Bristol, UK, was on the foredeck assisting with a headsail change from Yankee 3 when he was washed overboard. Although he was clipped on with his safety tether, he became separated from the yacht in the Southern Ocean at approximately 0814UTC (1414 local time) in a rough sea state, in 20 knots of wind, gusting 40.

Simon’s death is being officially investigated by the authorities, but in the meantime we have learned from other accounts that:

  • He was being dragged over the side by his tether and, while other crew members were trying to pull him back aboard, the clip at the inboard end of his tether bent open under the load.
  • Simon was recovered some 36 minutes after becoming separated from the boat, but did not survive.

As I understand it, the tether that failed was from Spinlock and used a Gibb-style snap hook.

It seems that a big contributor to the failure was that the jackline that Simon was clipped to terminated at a bow mooring cleat and his hook jammed under the cleat when it loaded up, with the resulting off-axis load causing the hook to fail.

The British Marine Accident Investigation Branch acted quickly by issuing a safety bulletin recommending that jacklines not be terminated on cleats.

Originally, I thought that was the important lesson from this tragedy, other than a reinforcement of what we already knew from other tragedies:

  • Being dragged is a very bad thing indeed.
  • Recovery, even by a large and strong crew, is very difficult.

There’s More

However, Drew Frye, who often comments here, and who is a climber, sailor, and engineer, with a deep understanding of fall arrest, took an interest and started testing Gibb-style snap hooks, including those used by Spinlock. This work resulted in some truly frightening results published in the March issue of Practical Sailor.

I strongly recommend that all offshore sailors read Drew’s full report. And yes, you will need to subscribe to Practical Sailor, but I recommend that anyway.

The key quote is:

To our testers’ surprise, off-center loads don’t have to be great to bend a snap hook open. In our tests, the Gibb-style hooks like the Spinlock Race Clip that Speirs was wearing began distorting under axial (side) loads as light as 275 pounds. At 300 pounds the hooks were fully open.

If that last sentence doesn’t make your blood run cold, I don’t know what will! As close as we can estimate, tether fall arrest and drag loads are at least double that.

Not Just Strength

And, if you read the full article, you will learn that that’s not the end of the problems with Gibb-style hooks. They also tend to “nose hook” (not fully attach) and jam up on webbing, or even penetrate it.

I can personally confirm the latter issue since Phyllis and I tried the original Gibb hooks some 15 years ago, and hated them for just that reason. In fact, we found them so dysfunctional that we discontinued using them after just a few weeks.

Replace Them

To me the conclusion is simple: All offshore sailors should immediately replace any of their tethers that use these snap hooks. Not tomorrow, not next week, now.

With What?

So, what should sailors who are using tethers with these hooks replace them with?

Login to continue reading (scroll down)

Inline Feedbacks
View all comments
Marc Dacey

Excellent commentary, but as an editor, I feel obliged to point out that the last name of Drew is spelled “Frye”.

Marc Dacey

Prudent seamanship, right there.

Matt Marsh

Thank you, John, for bringing this up and for not mincing your words or hedging your position. When something is found to be dangerously inadequate for the task, the only correct thing to do is to get rid of it – and to make sure that everyone else knows to get rid of it as well.

I still stand by the rule I was taught for tying off to scaffolding, etc. on skyscrapers: “Would that break if you hung your pickup truck from it? Yes? Then you can’t clip your harness to it.”

Jim Evans

Carabiners certainly aren’t the answer: when you need to hook on you need one hand for the ship and one for yourself, and unless you’re uncommonly dextrous a carabiner will leave you with no hands for either!

Stein Varjord

Hi John.
Thanks for clear words. Many in a similar position might try to be more “diplomatic”, at the risk of giving a more foggy message. Integrity is cool stuff. I have no fear that Spinlock will be neither angry nor noticeably damaged by this statement and truth. They can, and probably will, use it to move ahead with making better systems very soon. The many others making similar systems may be a bigger question. How many years will they need to change their standards? How many deaths? The regulatory entities will probably need to take action to speed that up…

Another topic is the solutions. I’ve become a firm believer, perhaps even fanatic 🙂 , in the system I have learned from this site, that all tethers are attached toy their correct object on the boat and the user moves from tether to tether. No loose tethers should be on the boat.

Among the many advantages of this system is that one can do away with the quick release system on the boat end of the tether. Any quick release system, even the Kong Tango, is a weak link. The description “quick release” is enough to prove it. By removing one of two quick release items on every tether, this risk is reduced by 50%, which is pretty good…

With the stationary tether system you have described, the boat end of every tether can easily be made as fail safe as we want it. Those attached to a jack line could be spliced (rope) or sewn (webbing) permanently to a small steel ring which will glide nicely on the jack line. If we want the system out of the sun or a tidy deck in harbour, there’s no need for a clip on each tether. We remove the whole system, jack lines too.

If we want a tether at a fixed position, we could just have a fairly large splice at the boat end. Put the end of the loop through the fixed point, thread the other end of the tether through the loop and pull tight. Simple and quick, both to use and to make.

These methods are, in addition to way stronger and less prone to mishaps, also lighter and cheaper. They will also make less noise and scratches on the boat.

Drew Frye

Technically, EN and ISO standards classify all of these contraptions as “connectors.” If search the net you will find the contraptions called carabiners, safety snaps, clips, and snap hooks. I go back and forth between carabiners and clips, but the correct term is connector… which is actually more confusing, to me.

I don’t like the idea of a tether fixed the jackline. I’ve found myself on the wrong side of a sheet or such a few times, and the simplest way to sort it out is to unclip. I believe that also violates the intent of the Off Shore Rule, because such a tether does not meet the referenced ISO standard.

As for screw lock carabiners, they are very secure and have their uses. For example, I have used them to attach semi-fixed cockpit tethers. In fact, many of the older Wichard padeyes will not fit the new via ferrata style connectors.

Stein Varjord

Hi Drew and John.
I see your points. Still, I feel not quite convinced. Standards are good, but not necessarily always right. Making things stronger than the standard might be good. I’ve not taken a final position on this, of course, but at the moment I feel quite strongly inclined to favor the no release at the boat end. If I’m at the wrong side of a sheet or so, I can just as easy unclip the tether from the harness, where there will have to be some type of snap shackle, of course. This seems especially practical if that end of the tether has the type of snap shackle that John uses and I have preferred for decades, the type found on some halyards.

If I need to go somewhere I can’t reach with any of the normal tethers, I’d say that’s a sign my tether system might need to be refined. If this occasion is a non standard operation, like in case of fixing some unusual trouble, I’d be inclined to bring the 3 meter rope with a clip that i use as safety when climbing the mast or such. That’s more suitable for attaching in unplanned places than a clip.

I feel that the biggest danger with a tether system is that it might be used wrongly, or not used, not that it lacks flexibility. It needs to be designed so that it works the best possible for performing all tasks. Figuring that out can’t be done in the heat of the situation. It must be designed right so that it fits the procedures that have been decided as the right ones.

It must be designed so it presents a minimum of hassle and nuisance. It must not need attention to avoid mishaps. It must be a no-brainer system that goes right without the need to be aware or careful. Removing the lump of metal with quick release possibilities at the deck side of the tether seems like a major contribution to many of those needs, with very minor negative consequences.
Maybe I’m wrong, but since I’m always right, that seems unlikely. 😀

David B. Zaharik

I would like to purchase some Kong Tango carabiners as recommended but I was wondering how many I should purchase. Not having sailed off shore, nor with more than one other person during higher winds and seas, how many sets are recommended? I will have (boat is being built by Boreal) a fixed centreline jackline system and some points in the cockpit. When sailing with multiple crew, how do you keep everyone attached? I very much like the idea of permanent tethers attached to the jacklines… but how many?

I see them offered on Amazon… is this source reliable?

I wholly admit being a neophyte and want to do this right. Comments please.

David B. Zaharik

I read it cover to cover… must have missed something or forgotten. Sorry


Thanks for this John.

Of course I purchased four of these at the Southampton boat show last year and the ones you are recommending are out of stock on the website. Anyway, I wanted to say I do appreciate the heads up on this important issue.

Drew Frye

I’ve been using Wichard Proline tethers for about 6 months. It’s a different motion, but at least for winter sailing, I find them easier with gloves. Summer, maybe it goes the other way. Overall, I’d rate them equals, strong and secure.

There are other via ferrata clips that may gain acceptance. There’s nothing magic about the Kong clips, other than their pricing is good and they’ve been in the marine market longer. ISC, Fusion, Edelrid, and others make nice ones I have also used. A good source is arborist gear companies, such as Knot and Rope, Sherrill Tree, and West Spur. These guys use them a lot. Some of them also make custom tethers with any rope, which might suit some folks.

I wish someone would find a good elastic webbing. I like to be able to wrap the unused leg around behind my back when not in use, something that does not work so well with rope. Someday…. Or maybe there is another way I have not considered.

Morgan Henry

I wanted to share a field report on the ISC SH903 clips, a triple locking carabiner that was included in the Practical Sailor review of tether hooks. After reading Morgan’s Cloud article and the one in Practical Sailor, I had three sets of tethers made using the ISC Snaps. I liked them initially, they are well constructed and easy to use. After a few days on a recent passage, from New Zealand to Fiji, salt water worked into the primary catch – the first lever to be depressed to open the snap. The salt residue caused the catch to lock either open or depressed, and it would take a few minutes of working the catch with fresh water to free it. Most of the snaps were locked up at some point in the passage and each day I would spend some time running fresh water through the mechanisms. My guess is that the fit tolerance is too tight and the salt build up causes them to jam, there is also a small spring in the mechanism that could either be corroding or locking up with residue as well. I won’t use these for our tethers in the future, I’ll see if I can track down Kong Tangos.

Alexander Srank

Dear John

This article I have for a long time in my memory – I am changing my tethers to climbing standard carabiners. But I also think the 1.80m tethers are too long – I think if Simon were on a shorter one he would have a much better chance. – I am gonna go to 1m ones especially for my kids.

My new boat will be a Pogo 12.50 that will not right itself easily. I recently read couple of UK marine accident investigation reports – one of them a very sad story of overconfident skipper with two novices who sailed to BF9 gale in Biscay. After capsize they had to cut themselves of the tethers as the boat was not righting itself immediately – similar fat ass flat design like Pogo. One of the crew drifted away, the skipper and the other crew member got eventually rescued from a life raft.

Would it not make sense if you see a really bad patch of weather coming to wear a short 1m tether and say a 5m second one ( perhaps rolled in a small coil and kept together with something that will disintegrate quite easily if you apply any force – light paper tape etc ). The idea being if you get under the boat you cut yourself from the short tether and swim out still connected to the long one. I appreciate the potentially cutting the wrong one, tangling of the long one etc but still better than nothing…

Do you think it is a complete bonkers idea?



Ivan sosa

Hi John,
First time poster but long-term lurker, and forever grateful for all the effort you and Colin put on this website. As I’m getting ready to climb my mast this season, I’ve been learning about safety secondary halyards and Prusik hitches (or other type of friction knots) and a question came to my mind. I searched through all the jackline-tethers series in your website but I haven’t seen it mentioned, so I figured I would ask directly.

I was thinking about using a centerline jackline, made of a low stretch rope, and a prusik loop to which I would attach my tether to. In the case of a fall, the prusik loop would stop the tether from sliding along the rope, as it happens when we use a flat jackline. If the jackline is not slack, and the tether is short enough, this would prevent us from getting near the water. Any thoughts on this?

S/V Balu

Matthieu Chauvel

Hi Ivan, I use two Petzl Ascenders, each one on its own tether ( when climbing my mast alone, each locked onto a different halyard just in case (and just one on a secondary halyard when someone else is helping me up), find them easy enough to slide up and down, makes for slow and deliberate climbing and descending, but safe…maybe worth a look.