Tether Hooks

zoidberg said:
I'll raise a point which seems to have been missed along the way, regarding the microcrystalline structure of alloy carabiners.

It was discovered many decades ago, during research into climbing 'crabs', that microscopic nicks and scratches on the surface of alloy 'crabs' have a serious effect on the Ultimate Load they can carry without failure. This is due, as I recall, to the surface treatment of the products being significant in the overall performance of the designs, and that microscopic as well as visible nicks and scratches have deleterious effects. I also seem to recall that exposure to salt.... i.e. salt water.... enhances this degradation.

Climbers of a certain vintage were very wary of getting their expensive 'crabs' wet on seacliff climbs.

This is a topic for engineers, but the research has previously been done. Perhaps it will re-emerge.
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I have read the research, and done some of the testing. The analogy is generally false because the damaged biners were generally "fixed" biners on draws that had been left hanging in the spray for many months, and in some cases over 30 years. This is different from gear that is taken home and rinsed once in a while. Second, lacking maintenance, the gates will seize up before the biner is damaged.

Also, common observation suggests that if this was a real world problem, I think we would have noticed by now (alloy masts, sprits, poles, and anchors).

Finally, the alloy via ferrata carabiners are something like 5x stronger than the Spinlock biner when side loaded. It's in the ISO spec. It's not close. ANY climbing carabiner is many times stronger in side load. You couldn't sell a climbing carabiner that folded up with a 500-pound side impact. It's a laugher... although a sad one.

I think we have some fear mongering going on here.
 
Separated by a common language,

Biners in the old Colony

Crabs in the Mother Country.

But both perfectly understand each of the words (though maybe not each other :) ).

Jonathan
 
Minn said:
There’s surely no reason not to use a stamped plate type hook at the harness end of a tether?
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Interestingly, in the US most race rules require that the harness end be quick release under load, like a spinnaker shackle. The World Sailing Offshore Rule does not have this requirement. Some tether manufacturers make one, the other or both types. Some are simply cow-hitched to the harness. I don't like the cow hitch type; it's possible to get on the wrong side of sheet and need to disconnect. The quick connect can be argued both ways and I've used both types. I'd rather not take sides, but just state a few arguments:
* If the boat capsizes, or if you are being towed in the lee bow wave, you would be better off disconnected.
* Spin shackles sometimes open when they should not.
* A singlehander is almost never better off disconnected.
 
penberth3 said:
A different hook each end, you would be able to use the tether the wrong way round.
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Having noticed myself in a similar situation, I make my double tethers with one blue webbing leg with a blue carabiner at the end, the other leg is white webbing with white carabiner. On the harness side a snapshackle with the opening ring somehow modified; I read two accounts of Mini650 skippers that had to open the shackle while under tension and they were very convincing, not much if being towed while swallowing the whole Atlantic but while being almost back onboard the tether had tangled somewhere (possibly looped around the lifelines) and was preventing them to come back fully onboard.
Also, when going down below I leave the tether attached outside, the sort of knot on the harness side definitely not for me.
 
I also like to leave the tether in the cockpit and clipped there when going below; the alternative of unclipping and going below with the tether risks forgetting to clip on again, particularly if one is in a hurry. If you have a snap shackle on the harness end it will be difficult to open without the customary inch and a half of square sennit on the pull ring, and with it it may open of its own accord if the tag gets trapped.
 
thinwater said:
Interestingly, in the US most race rules require that the harness end be quick release under load, like a spinnaker shackle. The World Sailing Offshore Rule does not have this requirement. Some tether manufacturers make one, the other or both types. Some are simply cow-hitched to the harness. I don't like the cow hitch type; it's possible to get on the wrong side of sheet and need to disconnect. The quick connect can be argued both ways and I've used both types. I'd rather not take sides, but just state a few arguments:
* If the boat capsizes, or if you are being towed in the lee bow wave, you would be better off disconnected.
* Spin shackles sometimes open when they should not.
* A singlehander is almost never better off disconnected.
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I have a hook end rescue knife (the Gerber one) that I keep as handy as possible and use purely for emergency scenarios - the cutting a life-line/tether was one I thought of, cutting clothing or life-jacket another. I regard it as cheap enough to replace at the same time as the tether but it still seems ridiculously sharp so I'm on the original at the moment. Whether or not I would be able to use the knife when being towed at 6 knots plus is another matter.
 
Minn said:
I also like to leave the tether in the cockpit and clipped there when going below; the alternative of unclipping and going below with the tether risks forgetting to clip on again, particularly if one is in a hurry. If you have a snap shackle on the harness end it will be difficult to open without the customary inch and a half of square sennit on the pull ring, and with it it may open of its own accord if the tag gets trapped.
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Hello Minn,
I fitted a larger than normal split ring on the snap shackle pin, then tied a largish button knot to the ring, with the two final protruding ends say 3-4mm long.
The button knot normally sits inside the split ring, kept in place by the two short outside bits: by just moving it a bit, the button knot flips outside the ring, it can be grabbed also by heavily gloved hands (those with two compartments, one for the thumb and one for the other four fingers).
It can probably be bettered, but not bad so far.
 
Roberto said:
Hello Minn,
I fitted a larger than normal split ring on the snap shackle pin, then tied a largish button knot to the ring, with the two final protruding ends say 3-4mm long.
The button knot normally sits inside the split ring, kept in place by the two short outside bits: by just moving it a bit, the button knot flips outside the ring, it can be grabbed also by heavily gloved hands (those with two compartments, one for the thumb and one for the other four fingers).
It can probably be bettered, but not bad so far.
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West Marine had to recall tethers that used split rings to attach lanyards; sometimes the split rings opened. They ended up welding them.

Make sure you test the rig with a maximum effort pull.
 
thinwater said:
West Marine had to recall tethers that used split rings to attach lanyards; sometimes the split rings opened. They ended up welding them.

Make sure you test the rig with a maximum effort pull.
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Yes I think it depends on the type of ring, I had to throw away some snap shackles (not necessarily for tethers) because they were single turn, just one turn of the tiny wire, once you pull it too much the wire deforms, becomes oblong and eventually just wiggling it it comes undone and releases the pin, which is conveniently thrown overboard by the internal spring. Also quite frequent on low quality blocks with similar arrangements.
I had it happen once on a leecloth, it had two quick release shackles on the upper brim, pull pull pull I was left with the wire of the ring in my hand, the time to try and open the shackle wooops it opened by itself and on the floor I went :d
 
thinwater said:
Connectors in ISO and EN speak.
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'Karabiners' from the German/Austrian; 'Snaplinks' from the English; 'Mousquetons' from the French.....'Clips'.... 'Crabs'..... 'Hooks'.....
But 'Connectors' in International Standards Organisation 'ISO-Speak'.....

The first technical work was done and published by the National Engineering Laboratory, at East Kilbride, led principally by G R Borwick. That remains available to academic research - http://discovery.nationalarchives.gov.uk/details/r/C6366
Considerable more work was done - and subsequently published - by other, commercial, entities and by the ISO Technical Committee ISO/TC94 - specifically Subcommittee 4, resulting inter alia in ISO 10333-5:2001 and ISO 10333-6:2004 ....with reference to ISO 9227: 1990 'Corrosion Tests in Artificial Atmospheres - Salt Spray Tests'.

Among the organisations interested in 'roll out' and 'corrosion' risks - and with something useful to say - are SATRA ( https://www.satra.com/spotlight/article.php?id=184 ) and WAHSA ( Guidance-on-the-selection-use-maintenance-and-inspection-of-connectors.pdf )

All professional organisations doing testing raise concerns re avoiding performance-degradation of connectors by being 'cleaned after every use in a marine environment.'

Others such as RaumerClimbing, Kong, Wichard, Secumar, SIS, Lalizas, Plastimo et al now refer to the published work of Technical Committee ISO/TC 188 within EN 1095/ISO 12401:2009. So also do Spinlock.

Perhaps the most important point to glean from all this is that industry insiders agree the existing Standards are not quite perfect, for yachting use. They include compromises, but are about as good as we are likely to get for some time. In the meantime, the following MAIB Interim Warning ought to be known and fully understood:

https://assets.publishing.service.gov.uk/media/5a535cfe40f0b648c72358ff/SB1_2018.pdf
 
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zoidberg said:
...Perhaps the most important point to glean from all this is that industry insiders agree the existing Standards are not quite perfect, for yachting use. They include compromises, but are about as good as we are likely to get for some time. In the meantime, the following MAIB Interim Warning ought to be known and fully understood:

https://assets.publishing.service.gov.uk/media/5a535cfe40f0b648c72358ff/SB1_2018.pdf
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Yes and no. It's pretty useless to have a product that can fail at 500 pounds if loaded crossways, as though we have complete control over this in a storm. In fact, industry standards for cross loading have been around for decades. This is why industrial standards have requirements for gate opening and cross loading. For MAIB to tell us that crossloading is a problem on a tether biner is basically 25 years out of date.

No, I think the basis for the standards has been around for a very long time. There just hasn't been a push or a lawsuit. I assure you any climber would snicker if you handed him a stamped connector. He would think it was either for hanging gear, you were joking, or you were clueless.
 
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zoidberg said:
'Karabiners' from the German/Austrian; 'Snaplinks' from the English; 'Mousquetons' from the French.....'Clips'.... 'Crabs'..... 'Hooks'.....
But 'Connectors' in International Standards Organisation 'ISO-Speak'.....

The first technical work was done and published by the National Engineering Laboratory, at East Kilbride, led principally by G R Borwick. That remains available to academic research - http://discovery.nationalarchives.gov.uk/details/r/C6366
Considerable more work was done - and subsequently published - by other, commercial, entities and by the ISO Technical Committee ISO/TC94 - specifically Subcommittee 4, resulting inter alia in ISO 10333-5:2001 and ISO 10333-6:2004 ....with reference to ISO 9227: 1990 'Corrosion Tests in Artificial Atmospheres - Salt Spray Tests'.

Among the organisations interested in 'roll out' and 'corrosion' risks - and with something useful to say - are SATRA ( https://www.satra.com/spotlight/article.php?id=184 ) and WAHSA ( Guidance-on-the-selection-use-maintenance-and-inspection-of-connectors.pdf )

All professional organisations doing testing raise concerns re avoiding performance-degradation of connectors by being 'cleaned after every use in a marine environment.'

Others such as RaumerClimbing, Kong, Wichard, Secumar, SIS, Lalizas, Plastimo et al now refer to the published work of Technical Committee ISO/TC 188 within EN 1095/ISO 12401:2009. So also do Spinlock.

Perhaps the most important point to glean from all this is that industry insiders agree the existing Standards are not quite perfect, for yachting use. They include compromises, but are about as good as we are likely to get for some time. In the meantime, the following MAIB Interim Warning ought to be known and fully understood:

https://assets.publishing.service.gov.uk/media/5a535cfe40f0b648c72358ff/SB1_2018.pdf
Click to expand...

Do you have a link to saltwater testing that we can read? The above are either behind a firewall, general information, or convoluted references.
 
zoidberg said:
All professional organisations doing testing raise concerns re avoiding performance-degradation of connectors by being 'cleaned after every use in a marine environment.'
Click to expand...

Aluminium is a great material (I need to say this, as I picked an aluminium boat :)), but it has to be the right grade of aluminium in the right application. People tend to think of all aluminium metals as having similar properties, but they vary very substantially depending mainly on the composition, but also heat treatment etc.

Most sailors will be familiar with aluminium from the 6 series (such as 6061). Most masts, sail-drives etc are constructed from this type of aluminium. It has reasonable corrosion resistance. Aluminium from the 5 series (such as 5083) is much more corrosion resistant, but unfortunately this grade of aluminium cannot be extruded, which means its use is mainly confined to boat construction (such as hulls) and not a great deal more.

Climbing carabiners are almost always constructed from aluminium from the 7 series (such as 7075). 7 series aluminium is very strong, but has poor corrosion resistance. Anodising helps substantially (most carabiners are anodised) but cannot make up for the fundamental poor corrosion resistance of the 7075. 7075 needs a lot of care in the marine environment.

There are many articles warning climbers about corrosion in aluminium carabiners. These warnings are for people using aluminium 7075 carabiners in merely a damp enviroment such as caves, or even just in humid countries, rather than the more aggressive salt water marine environment.

http://ferforge.tripod.com/Malzeme004.htm
“7075-T6 and other high strength aluminum alloys likely to be used for vertical equipment are not very corrosion resistant. No amount of excess strength capability in a new carabiner is sufficient to compensate for the reduction of strength that will occur if aluminum carabiners are left in caves for a long period of time.”

http://rockclimbingcompany.blogspot.com/2009/09/corrosion-in-climbing-carabiners.html
“Each year DMM receive back a few carabiners where the surface of the carabiner has corroded and exfoliated. Almost invariably these carabiners have been to Thailand (although DMM have seen similar corrosion from carabiners used in Hawaii).”

https://dmmclimbing.com/Knowledge/August-2011/Anodising
“This is largely because the alloy used to make most climbing carabiners - 7000 series aluminum alloy - is quite susceptible to galvanic and exfoliation corrosion”


Aluminium carabiners have a lot of appeal sailing. The lighter weight compared to stainless steel carabiners is a significant advantage. I also think that companies producing equipment for climbing are manufacturing more advanced, safer products, than the marine equivalents.

However, if you do use an aluminium 7075 carabiner (and I think with care they can be used), don’t imagine it will have a similar durability and corrosion resistance to most other aluminium deck hardware. 7075 has a quite different corrosion resistance compared to 6061.

Give the 7075 aluminium a good rinse after use and let the tether dry before storing down below in a dry environment.
 
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The corrosion of climbing carabiners around boats is real enough. I've used wire gate carabiners for utility purposes (fishing gear, securing dinghys, deflecting dock lines, etc.) for decades, and after 5 years or so of continuous exposure they begin to show some damage. Typically, it is the inside radius, where they bear on a steel hanger or pad eye under high load. This happens even more quickly to climbing carabiners, because their use around rocks leads to many failures of the anodizing.

On the other hand, I started using Kong Tango clips on tethers 8 years ago and they remain completely corrosion free. Why? They are rinsed on occasion and the moving parts are lubed with waterproof grease several times each year. I don't dump them in the bottom of a locker, wet. There have been complaints of corrosion by people who store them carelessly, but I can't imagine storing climbing gear in such a manner and expecting it to be safe. That's just inconstant with my thinking. I never put ice climbing or rock climbing gear away wet either. It is inspected after each use and put away dry, out of the sun but well ventilated.

In fact, both of these Kong clips have now broken. As part of a testing program, in the wake of the CV 30 accident, both were pull-tested (one nose nose hooked, the other cross loaded) and the results compared to factory QC values and new Kong biners. There had been no change. Certainly, the result with a corrodes carabiner would be different. But I did check those two. As I recall, they were about 4 times stonger than the Spinlock example.

The Wichard stamped biner is many times stronger, comparable to the via ferrata biners. If you like a stainless biner--and I can see good reasons--that one is safe. Personally, I find it hard to use. But it is strong.
 
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