Zero stretch rope

[evildrome]

A length of motorcycle chain. For your purposes, used will be fine.

 

[profchris]

My Dad was in the navy for the last couple of years of ww2, and on a destroyer he was on they were using steel wire to tie up the ships in dock. One of those steel cables gave way, and the flailing cable took off the legs of a couple of deckhands. The story was you got no audible warning of failure of a steel cable, but you could hear the rope ones groaning! ProfChris, having driven the winch at little grands and learnt to fly there, I’m curious what your experience was of the man made ones? Do they break less often than the steel ones? And if /when they break, can they be repaired as quick as the steel ones?
Stuart

At a guess, steel would break once every 6 flying days. Dynema might break once or twice a year.

Total repair time about the same because Dynema doesn't tie itself around the winch!

 

[Henniep]

True to the zero stretch, but, I do need to minimise it. I have a heavy lath set up in my bow press. The press has 14” of travel, the nylon rope in there at the moment pulled the tip on the lath for the first 6 inches of travel, the next 6 inches of travel were all stretch on the rope
I have jute cord I could twist up but jute fibres are quite short. The hemp rope looks good, correct for period too (14th century) when I need to make a stringer

Would a nylon rigging/lifting sling not be an option. It's designed for the purpose you intend, and stretch is minimul

 

[Stevekane]

Dynema is unbeliveably strong to the point where its almost impossible to cut 3mm with very sharp scissors. Be aware that some Dynema lines are sheathed in a regular woven material I beleive because Dyneema is not UV resistant, the straight unsheathed dynema was just a silver grey colour but perhaps thats changed?. Dynema is slippery and the only knot I found that held reliably was the one fishermen used to tie hooks.
Its one of those things that leave you marveling just how strong such a fine line could be.
Steve

 

[stigg]

I use loads of Dyneema on my son's sailing dinghies which require constant repairs. It's amazing stuff. Some racing boats use it as rigging now, replacing steel wire or rods as it is considerably lighter. Weight at height is most important. Splicing it is really very simple and can achieve 100% load. There are loads of resources on line.
Knotting it works ok up to a point. It will either break at the knot or more likely the knot will pull through as it is super slippy. We do doth depending on application. A 5mm D12 won't break before about 2000Kg and at 200Kg there will be virtually no stretch. Nothing has zero stretch. It will set you back about £1.50/m
D12 is quite fragile however, so if exposed to any sort of abrasion use a sheathed version with a polyester cover. This is a bit more involved to splice but knots work better.
Local chandler is the best source and is a mine of information.
I use
http://1stmark.co.uk/
Dan

 

[sometimewoodworker]

No need to splice most knots will hold, bends will tend to slip though.

That is a rather ridiculous statement, there are a couple of thousand knots and a hundred or two bends and if you don’t know what you are doing either or both will hold or slip

 

[stuckinthemud]

Bowline is my “go-to”

 

[Phil Pascoe]

I was told by a coastguard about 35 years ago that they were advised not to use bowlines on nylon ropes.

 

[rosinante]

I was in RN , the nearest to a non stretch rope was Manilla , this was used wherever life was concerned, it was used as life lines on seaboats, it was unique in the fact that it creaked and gave an audible warning when excessively loaded. Man-made fibres such as Nylon and Terylene ropes could stretch up to 45% of their lengths , often the internal friction of the fibres created enough heat to fuse the rope into its loaded length rendering it useless, when splicing man-made ropes 5 tucks and dogging of the ends was recommended practice , Hemp , Manilla and Sisal were spliced with 3 tucks , dogged or tapered thereafter. This is info that is surely superseded now , the nearest Iknow of a common " dead rope is polypropylene " hth

 

[stuckinthemud]

I was told by a coastguard about 35 years ago that they were advised not to use bowlines on nylon ropes.

Any ideas why not?

 

[Phil Pascoe]

They slip, apparently. Don't shoot the messenger.

 

[stuckinthemud]

Wouldn’t dream of it. Who else would run the Secret Santa?!?

 

[dephill]

I’ve got plenty used dyneema in approx. 7mm which has breaking strain around 5t I think so you’ll get very little stretch on 200kg. If you give me an exact length I can splice soft loops in both ends.
It is orange though.
I can make it up and post it to you for postage cost if you like.
It’d be a week or so till I’m home to do it though.

As a bonus here’s a pic of some OX40 30mm braided (dyneema like) rope with an MBS of 82ton.
It came the wrong length so my colleague and I had to splice one end.

Might be overkill for your needs.

 

[worn thumbs]

Dyneema is great once the initial stretch has been dealt with.It needs to be stretched,just once,for the structure to become stabilised.The comments about UV are quite correct but if Kevlar is available at a tempting price,ignore the temptation to buy it as it too is subject to UV degradation and it gets quite treacherous if wrapped round a tight radius while under load.

 

[pe2dave]

Any ideas why not?

Untieing a bowline that has been 'worked' hard is darned near impossible. Lots of easy to undo options.

 

[Dave Moore]

And it stretches.

The thing to do with hemp is to prestretch it before use as it coils up if not. When we still used rope blocks at work we used to stretch it between a steel column and the tow bar on the works lorry, just need to ensure you don’t go too far and snap it.
Regards,
Dave

 

[sometimewoodworker]

Untieing a bowline that has been 'worked' hard is darned near impossible. Lots of easy to undo options.

That is incorrect, try comparable ropes with different knots that have been worked as hard and a correctly tied bowline is probably going to be the knot that holds best and is the easiest to undo.

There is a vast difference between knots that hold well and knots that are easy to undo. Having studied the subject of and on for over half a decade and bought my copy of Ashley about the time I first got interested and having tied a good percentage of the content, I am reasonably familiar with the subject.

However the bowline and it’s variations while an important knot to know how, and where, to use it is certainly not necessarily the best one to use.

the answer that for many nylon ropes, that it’s too slippery for a regular bowline to be safe, is correct

 

[dephill]

I’m afraid Dave, I pretty much agree with sometimewoodworker.
The bowline is always easy to untie and holds well in most rope as long as it’s kept loaded.
However, it can undo itself if unloaded and wobbled/shaken a lot. It also reduces the the rope SWL to about 60%.
The latter two are possibly the reasons it was advised against by the coastguard.

For reference I’ve been tying knots for a living (rigging, rope access) and for a hobby (rock climbing) for 20years.

 

[sometimewoodworker]

However, it can undo itself if unloaded and wobbled/shaken a lot. It also reduces the the rope SWL to about 60%.
The latter two are possibly the reasons it was advised against by the coastguard.

The sometimes unstable knot is totally dependent on the material the road is made from and the way it has been layed up. Woven nylon, used extensively by climbers, is rather more slippery so in some circumstances the bowline isn’t the best choice, though a bowline on the bight even unloaded is totally stable.

On the reduction of SWL all knots reduce SWL some by as much as 90% if you look at the picture above by @dephill the splice, though it reduced the SWL by a small amount, is no problem however the use of a small (relatively) shackle (it looks to be a 4.5 SWL one that has a breaking point at 40 tonnes) has reduced the SWL by up to 90%. This is almost certainly allowed for the the rope strength requirement, though adding a thimble eye would increase the SWL by a large factor.

BTW @dephill have you ever taken a look at Ashley? If not it’s a fascinating book for people who use rope, when I bought my copy it was 84s (£4 4s 0d) today the same edition is £73.81.

This is some fancy work

 

[pe2dave]

That is incorrect, . Having studied the subject of and on for over half a decade and bought my copy of Ashley about the time I first got interested and having tied a good percentage of the content, I am reasonably familiar with the subject.

If you've a copy of Ashley, you should agree it's a poor choice for a stressed knot.