Rope terminations

[Ropey]

double braid is kernmantle, by kernmantle do you mean rope which has a core which bears >60% of the load?

 

Double braid is not Kernmantle! These are two totally different constructions.

 

I would also question whether a sewn termination is stronger than a splice, with some fibres the sewing can reduce the strength of the rope as the needle breaks the fibres as it passes through the rope

 

We have tested both knots, splices and sewn terminations, the statement made earlier about knots reducing the strength while not accurate in % is in fact truce, some knots can reduce a ropes strength by 50% which I have personally seen. On the other side of the coin I have also seen spliced ropes retaining 100% of the original break load of a rope and during testing the rope failed before the splice.

 

All this depends on who has done the splice or knot and the care taken. Not all knots and splices are the same I can tell you.

 

I read somewhere in Arbtalk that you should take just that little extra bit of time to dress you knots and may sure there are correct, this I would reinforce 100%. The difference is huge.

 

[finchyo]

I would also question whether a sewn termination is stronger than a splice, with some fibres the sewing can reduce the strength of the rope as the needle breaks the fibres as it passes through the rope

 

This isn't true as the the needle separates the fibres as it passes through the rope during sewing. Sewn terminations are stronger than a knot and i like the idea of less bulk and no chance of it coming undone (i hope).

 

I have always used a bowline to tie into and it has been fine but as i'm getting a new rope and they can put the sewn eyes on for free, then might as well go for it. Might try spliced eyes at some point in the future too. As the sewed section of the terminations are covered in a plastic sheath, was just wondering if it is able to pass through the small hole on a standard cambium saver with a little push; say when you are setting up your anchor from on the ground. i have heard i might need a cambium saver like this one from petzl, but with a small screw gate instead of the small ring. Anyone used sewn terminations with a standard cambian saver?

[educated arborist]

Double braid is not Kernmantle! These are two totally different constructions.

until i began working with rope manufacturors i thought the very same, the word kernmantle is German & means core & outer/sheath, and i recently forgot this which lead to great confusion. it would be wise for every one in our industry to stop miss-using this word IMO

I would also question whether a sewn termination is stronger than a splice, with some fibres the sewing can reduce the strength of the rope as the needle breaks the fibres as it passes through the rope

all testing which i have knowlege of (on arborist ropes widely used within the UK) has found the opposite, one or two of a batch of ten splices may be as strong as the sewn ones, sewn are much more consistant & yes this it is alot to do with the splicer/splice every one(including factory splices) has a different BS, but as i said earlyer this is not really of any relevence as splices are more that strong enough to meet CE standards etc.

the statement made earlier about knots reducing the strength while not accurate in % is in fact truce, some knots can reduce a ropes strength by 50%

as i said earlyer this is all prety achedemic but i was refering to PPE splices being rated at 22kn (which they are not) & a well dressed knot maintains a perfectly acceptable BS

I have also seen spliced ropes retaining 100% of the original break load of a rope and during testing the rope failed before the splice.

true but rare and yes spot on not all ropes, splices or knots are not the same

 

My testing into milking was not to establish wheather or not milking towards a splice weakens it as this is allready well documented, unfortunately the extent & primary aim of the test is confidential :blushing:sory:blushing:

Edited January 26, 2010 by educated arborist
typo

[educated arborist]

sorry for the confusion, yeah i meant kernmantle as core bearing the majority of load. Thats a really interesting test you got going there but would having both ends spliced mean that the ropes gets used alternate ends and so the bunching towards the splice gets stretched back out evry time its used? Having just one spliced eye means that all the bunching is always going to be going towards the eye? In the test, are the 5 descents done without milking the rope back away from the splice or just left as is and repeated? Are you doing the tests with a bowline on end to act as a constant to see what the bunching does to this?

Nice idea for a test mate:001_smile:

 

unfortunately the full extent & primary aim of the test is confidential but yes a bowline is also to be tested however a bowline can be untied & the milk. milked off the end & cut off where as on a rope spliced both ends this is not an option. No the milk was not mlked back away from the splice the theory is that if a rope milked towards the middle is subjected to a long decent or two in the same direction then the milk would be milked to that end anyway. The five decents were simulating/accelerating prolonged use. When maintaining my clients ropes i have experienced un re-moved hollow milk at the end of a line in excess of 1m within 6 months of purchase (more than enough to prevent a splice from working)

[John Shutler]

unfortunately the full extent & primary aim of the test is confidential but yes a bowline is also to be tested however a bowline can be untied & the milk. milked off the end & cut off where as on a rope spliced both ends this is not an option. No the milk was not mlked back away from the splice the theory is that if a rope milked towards the middle is subjected to a long decent or two in the same direction then the milk would be milked to that end anyway. The five decents were simulating/accelerating prolonged use. When maintaining my clients ropes i have experienced un re-moved hollow milk at the end of a line in excess of 1m within 6 months of purchase (more than enough to prevent a splice from working)

 

not sure i get your point, if there is milking at the opposite end of your line to the splice, why would this affect the splice

[High Scale]

If a rope that is spliced either end milks then surely you will be left with a rope that has excess cover/bunching in the middle of the rope?

Edited January 26, 2010 by High Scale

[Jamie]

Educated Arborist.

 

In reference to milked ropes reducing the strength of the splice, what rope constructions are we/you talking about.

 

Having spliced many ropes for my use and a few for others i'm well aware that baggy splices could drastically reduce the strength and holding abilitly of the splice.

 

I'm aware that Yale Blaze and XTC milk considerably so i'd never splice both ends of a line. I have spliced both ends of a Samson Arbormaster line after a few months of milk free service (one eye was spliced before service then the second was spliced after a few months use).

 

I've never understood removing the milked sheath. While aesthetically not nice, i'm unsure of how many people actually use the last meter of their rope(this could be an argument for removing the milked sheath). I tend to leave the milked end on and tie my stopper knot above the milked tail, should i find myself at my stopper knot it would give a good working length of rope to use.

 

I'd be interested to hear your results and your methods (not methodology, such a miss used word but thats another topic). I've an open mind and a vested interest as i splice a fair few cords and have played around with splice constructions with positive results.

 

I do however agree with your statements about stitched terminations being more repeateable and less prone to human error than splices or knots.

 

Jamie

[Jamie]

If a rope that is spliced either end milks then surely you will be left with a rope that has excess cover/bunching in the middle of the rope? I mean, the splice isn't going to fall off is it?.

 

I'd imagine you'd naturally favour one end so any milking would gravitate to one splice then bunch up below one hitch. any bagginess in teh splice would lead to less secure splice. strong splices have gradual tapers, i'd think that baggy splice would lose this gradualness of the taper and become weaker. the splices i have had broken have always broken at the start of the taper or where there has been a sudden change in taper diameter. I don't like the sudden taper in samsons Tenex / tenex-tec directions. i always perform a smoother more gradual taper.

 

sorry i've deviated a bit

 

Jamie

[educated arborist]

Jamie i would be more than happy to share some of my results with you PM me your details & we'll talk more. Certain ropes milk worse than others & your pre-milking before spliceing the other end will reduce the risk of a splice becomeing baggy moreover weakened. Construction type is a factor but they vary so much brand to brand that no strong correlations are aparent. Hollow milk shold be removed as it occours to mitigate against a climber coming off the end of his/her rope (it may look like youve got a metre or 2 to go but as you hit the hollow bit down you come)

 

john i think you've miss read something

 

High scale i've allready answered that 1: "the theory is that if a rope milked towards the middle is subjected to a long decent or two in the same direction then the milk would be milked to that end anyway"

[john dawson]

splices are way stronger than knots.

 

With braided ropes (ropes like Arbormaster, xtc, blaze etc) you have to watch out for the rope milking (where the sheath of teh rope stretches and you end up with a floppy end to your rope).

 

its no good having a floppy end in your rope........