Rope Strength

[11redrex]

Anyone know how to work out the strength of a bit of rope ?

I used to know how to do it for steel wire rope or chain, probably still do, somewhere deep in the recesses of my beer addled brain, but not for ropes.

I found a nice heavy piece of mooring rope today, roughly 5m long and 40mm thick, spliced a loop in both ends, instant tow rope. But how strong will it be ?

On a separate note I saw an unmanned boat floating down the river today.:augie

 

[Adz]

I have a 10 metre length of anchor rope, 4 strand, combined total of 20 tonnes

Everybody who has seen it including hard core off roaders said "that will snap"...

1 year later & many recoverys later its still going good & strong

As i tried to explain to them as my uncle explained to me.

1 strand is rated at 5 tonnes & thats enough to hold a boat to its mooring...

We have plenty of water going folk on here :thumbs

The easiest way to find out is try & tow something big :lol

 

[11redrex]

The exact same type of rope was also attached to the crane they use to lift boats out of the water. It's three strand, so that'd make it ok for 15 tons ?
Gonna try and pull my massively fat chip eating parking across my driveway leaving her bin bags untied neighbour off her sofa, she's gotta go around 10 tonnes.
I wouldn't want to pull 5 tons with one strand of this though, it's synthetic hemp and probably about 200 years old.

 

[rustic]

y

Anyone know how to work out the strength of a bit of rope ?

Modern ropes are affected by the weather, polypropelene is weakened very quickly in sun light.

Natural fibres are affected by moisture and the storage environment.
I am not an expert, but the strength of your rope is unknown, if you want it to pull 10 tonnes you will need to have it tested to at least twice this, if it is used for lifting then at least 5 times.

You don't know if it has been over stressed or kinked or knotted thus reducing it's strength.

Before you use it as a tow rope consider what would happen if it broke, I wouldn't stand under my Mav if it was hanging from your rope.
But if it supported a 10 truck truck first I would then take a chance.

Be aware that there are a lot of ropes around of this size that are used on decking, they will not be as strong as their original counterparts.

 

[elty001]

just buy one thats been rated for what you are doing:thumbs
got a tow strop and 2 shackles from a place in chesterfield,derbyshire.
they are a maritime set up but also do good recovery strops.

 

[11redrex]

I've got a strap with hooks on both ends for towing, up to 4 tonnes, a chain with a hook on one end and a loop on the other which will lift 6.25 tonnes straight, and a bit of old strap with a hook on one end which I towed and unintentionally lifted my T2 off the floor with. Gonna hook the rope round something heavy tomorrow and see what it'll pull. In the meantime it looks good held onto the front bumper with cable ties. Very yee-ha redneck, even if I do say so myself.

 

[Deleted account DD]

Very yee-ha redneck, even if I do say so myself.

you need a jeep :augie

To add to answer ..................


we used to have to test ropes and chains every year (well we as in the ground equipment techs) It was quite suprising how quickly they deteriorated as desc by rustic. I wouldnt rely on a 2 ton rope remaining at that once its been out and about a bit.

Tend to agree with the Adz observation technique and just replace it if it started fraying or visibly deteriorating :thumb2

 

[Thomas-the-Terrano2]

guys, is it safe to use a big shackle to join to straps for straight
not snatch recovery. just felt even my longest strap was bit
short if other guy followed thru as it were.

guess if not could loop one strap thru the other's loop. just dont
fancy the shackle flying loose.

 

[Thomas-the-Terrano2]

I've got a strap with hooks on both ends for towing, up to 4 tonnes, a chain with a hook on one end and a loop on the other which will lift 6.25 tonnes straight, and a bit of old strap with a hook on one end which I towed and unintentionally lifted my T2 off the floor with. Gonna hook the rope round something heavy tomorrow and see what it'll pull. In the meantime it looks good held onto the front bumper with cable ties. Very yee-ha redneck, even if I do say so myself.

looks the part, but surely better in boot, away from thieving gits and not getting
wetter and dirtier than necessary.

surely if you're gonna rescue more likely be from your rear towbar.
stuck on front implies you might need a tug, and if you did get that
fatr and that stuck perhaps retreat would be safer.

 

[makeitfit]

Rope you say
Well I use and abuse rope big time under massive loads on me cat amaran:lol
You need to know what material the rope is, then what strand make up it is, plaited or twisted or multi thingy braided:augie
Serious loads are doable on rope much smaller than steel and safer too:thumbs
So there you go, you tell me how long it is and I'll tell you how strong it is

 

[thor]

guys, is it safe to use a big shackle to join to straps for straight
not snatch recovery. just felt even my longest strap was bit
short if other guy followed thru as it were.

Only problem with joining two ropes together especially if you use a shackle....if the rope snaps, the shackle could become a deadly missile..

Also see this on ebay.... Item number: 150502645798
Just an example they do much more.
I have bought from them a couple of times and I have two wowzer straps for towing. :clap

 

[Thomas-the-Terrano2]

Only problem with joining two ropes together especially if you use a shackle....if the rope snaps, the shackle could become a deadly missile..

Also see this on ebay.... Item number: 150502645798
Just an example they do much more.
I have bought from them a couple of times and I have two wowzer straps for towing. :clap

cheers Thor just my concern, wasnt going to be full snatch recovery but even in
gentle tug could get snatch if one vehicle slackens it then tensions.

in hindsight, glad he couldnt find his screw in tow eye, and i had bit of fight for
traction setting off solo, though perhaps in first low got wheel spin. these modern
ambulances are heavy, reckon 3.5/4 tonne chassis with all paramedic gear carried
these days, reckon he had more weight on his back axle anyway, plus had what
lock liked tyre socks? shackle thru windscreen could have took some explaining...

 

[Thomas-the-Terrano2]

cont. suspect if had been really stuck, request to take his paramedic gear in
troll would have safer all round. by time followed to incident on my route,
a police terrano!! was arriving with support and a skoda 4x4 octavia?
responder vehicle. glad we didnt need their help in turn.

will loop my straps together ready for next job, one loose end in tow jaw
and any shackle be under disabled vehicle, if its tow hook isnt useable.

 

[11redrex]

Synthetic rope doesn't fly about when it snaps, it just drops on the floor. It doesn't store energy. Wire rope is the killer, that's why the environmental agency (for one) doesn't use it on their winches anymore.

 

[thor]

I recently checked my towing strap is up to 14 ton... datledo nicely :thumb2

 

[rustic]

I recently checked my towing strap is up to 14 ton... datledo nicely :thumb2

Well the chassis will seperate first....
Grit is the biggest killer of straps, I am not sure how to clean them, but I put my mooring ropes in a laundry bag and in the wash they go on a cool wash, however I would not reccommend doing this with towing or lifting straps or strops, as I wouldn't know what would happen to the stitching or the material. :nenau

 

[11redrex]

think I'm getting close to fully kitted up now. Got some shackles and a beacon today, just need a winch now and I'll be ready for anything. Oh, and I may have found a source of cheap waffle boards if anyone is interested :augie.

 

[Fez_uk]

how cheap? as i have just bought some.

 

[11redrex]

Dunno, I ain't nicked 'em yet :augie

 

[rustic]

Dunno, I ain't nicked 'em yet :augie

Fez has got some:thumbs :augie :augie

I was thinking of using an off cut of one to act as a step on the rear of my boat 24" x 16" would do, in white or light grey, but I'll probably now use marine ply and non slip track mark. Another winter project.:doh