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Post by JohnV on Jan 24, 2021 12:55:35 GMT
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Post by Jim on Jan 24, 2021 13:05:09 GMT
it makes sense to me that a splice is as strong as the rope, its woven together, more tension, more grip, its twice the thickness.
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Post by JohnV on Jan 24, 2021 13:47:35 GMT
it makes sense to me that a splice is as strong as the rope, its woven together, more tension, more grip, its twice the thickness. I was always taught that a splice was only about 85 - 90% but in view of your post I have been doing a bit of investigating. According to a report from the University of Strathclyde I found and have been reading it looks like you are ..... in practice correct. It does seem to be much more complex than it first appears though and also depends on the size of the rope (obviously the number of tucks matters but it is only weaker in practical terms with less than three and the improvement with more is so tiny as to be insignificant.)
The bit that I found most interesting was that failure of short splices occurred at the end of the splice (changed angle/density of strands ?) and braided splices had another anomally splice efficiencies for 6mm was 61% 8mm 98% but paradoxically 12mm was down to 73% again (something worth bearing in mind if you are using braided)
another odd thing was that the strength of comparable three tuck splices was not dependent on the skill of those who made them. !!!
Well, Well, Everyday's a school day
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Post by quaysider on Jan 24, 2021 14:20:47 GMT
To be honest, unless it's a large diameter, expensive rope, I don't bother. The cost of a new long centre line for a narrowboat is not a lot .... replace it and cut the damaged line into good pieces and make into new short lnes, grommets, strops, rope slings etc. .... there is always plenty of re-purposing possible for rope. why put a weak spot in a line that is important. I would suggest that the centre line is the one line that can safely be the weakest because its a handling line, not a mooring line, and the weakest part in the handling chain will be the human. In any case it all depends upon just how damaged the line is and we don't know that. I have never had a centre line break but have had a few bow or stern lines snap when idiots come past too fast. I beg to differ on this one - My centre line snapped - my own fault as I'd not noticed it chaffing where it passed through the roof mounted fairlead just as I was trying to pull it in on the floating lock landing on the Aire in Leeds... luckily, on that occasion, there wasn't much flow on the river and I was able to jump back on but had it been a bit fruity, it could have been a disaster. As a result, I now have new centre lines (I've one each side) every spring AND have them pass through rubber tubing where they go through the fairleads.
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Post by Deleted on Jan 24, 2021 15:33:12 GMT
Rivers innit ! Nuf said Rog
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Post by phil70 on Jan 24, 2021 23:24:12 GMT
I had a centre line snap, we had not long had the boat and one day I moored up,stepping off with the line and tried to take a little bit of way off it by a turn around a bollard. The line came with boat and just went Ping! it was a white polyprope 15mm dia and was swiftly replaced with a nice Hempex line. Phil
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Post by tonyb on Jan 25, 2021 8:53:35 GMT
I had a centre line snap, we had not long had the boat and one day I moored up,stepping off with the line and tried to take a little bit of way off it by a turn around a bollard. The line came with boat and just went Ping! it was a white polyprope 15mm dia and was swiftly replaced with a nice Hempex line. Phil
I think Hempex is polypropylene but it certainly seem less affected by being exposed then the CaRT "blue string" type poly-rope. I suspect all poly-rope degrades and looses strength over time, some faster than others. At least Hempex seems not to degrade into hard splinters that you get in your hands.
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Post by Jim on Jan 25, 2021 9:08:13 GMT
I had a centre line snap, we had not long had the boat and one day I moored up,stepping off with the line and tried to take a little bit of way off it by a turn around a bollard. The line came with boat and just went Ping! it was a white polyprope 15mm dia and was swiftly replaced with a nice Hempex line. Phil
I think Hempex is polypropylene but it certainly seem less affected by being exposed then the CaRT "blue string" type poly-rope. I suspect all poly-rope degrades and looses strength over time, some faster than others. At least Hempex seems not to degrade into hard splinters that you get in your hands.
I've used 16mm synthemp, happy with it. Any deterioration has happened where the centre lines chafe on the lock side. I might try the cycle innertube sheath on that bit.
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Post by IainS on Jan 25, 2021 17:17:20 GMT
Interesting that they consider an eye splice as 100%, even after stating that the failure point is always at the splice! I don't agree with their descriptions of the long splice; what they call a long blind splice I call a long splice, although it is almost impossible to do with synthetic rope. The loss of strength isn't as much as claimed if the joining strands are tapered rather than just halved. I use what they call a long splice ( and I call a "cheat" long splice!) for tow/recovery ropes , to make them into a loop, which spreads the wear. Only had one failure, and it wasn't at the splice!
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