Kinetic rope snapping

[extreme90]

i can understand why h wont use his winch, ill only use my winch's to recover a friend of mine or someone who i know and he just needs a helping hand, cos after it, when your solenoids are smoking, alls you get is  a chears mate, and thats it
my friends offer pay but i refuse cos itw what mate are for,
and that is why i dont carry a KERR and why no 1 hooks one up the the arse end of my 90
the chap in the 90 was a lucky [!Expletive Deleted!] that the rope didnt send anything else hurtling towards him, instanly he was rubbing his head, so that shows how much force was behind that rope,
anyhows such is life and everyone learns
dan

[redneck]

Another video clip of kinetic rope letting go, in this one i believe the tow ball or a shackle does the damage  :shock:
http://video.google.fr/videoplay?docid=-3054143592822346647

[Mr Bump]

David - what was with the guy in the red RR hitting the Suzuki in another video you posted. Doesn't he like his truck or something?

Mike

He likes his motor , but he is just a nutcase!

And he doesn't wear a belt  :roll:  :roll:

[Bulli]

Therm, thats what a lot of people think....just wang it in first and hit the load pedal...not the right way though.
If you have traction then you should have the rope nearly taught. Set off at walking pace and when there is no more stretch hit the brakes, theory is the rope contracts recovering the stuck vehicle.
If you have less traction then you should allow more slack...but not a 3 meter run up. The energy stored in a stretched KERR is huge, its the same as the car creates by its movement forward by 3-4 feet.

I have a brand new KERR that has been sat in my recovery box for over a year now and hasnt been used in anger. I will use it when appropriate and have used them before.

I dont think the recovery would have been more successful/safer if a non stretch rope were used .I think he needed winching or poss pulling forward. Its hard to say from a video though and im sure the guys on scene assesed it better than i can

[Eeyore]

Okay, quick bit of info re: ropes, knots and hysteresis.

Knotting a rope will reduce it's strength locally by between about 40 and 90% depending on the rope and the knot used. Elasticated ropes, bungees and ropes of a plaited construction are generally in the latter catagory (splicing is a good thing here).

Whilst a rope may support, for example, a ton of load; apply a 70kg load to it quickly (as in a fall situation) and it snaps. It also places significantly more load than the 70kg on the anchor points. F=m X a and all that.

Kinetic rope was desinged to allow significant energy to be transferred to an object (like a stuck tank) whilst reducing the peak strain on the anchor point (t reduces the effective acceleration placed on the anchor points). This is it's job; it goes taut, you keep it taut and keep pulling (as I beleive the Hussars are taught), thus maximum energy can be transferred to the stuck object whilst the peak load is kept in check. The elasiticy is pretty irrelevent thereafter, unless the pulled object is on firm ground and can roll freely.

All the info suggesting that it's the elasticity of the rope that moves the vehicle is sadly misleading - it's the energy of the other vehicle that does the job, the rope just protects the anchor points.

Here's another really cool example - go climbing and use a semi-static rope. Fall off. Kiss your pelvis good bye. However, use a 'dynamic' (i.e. stretchy) climbing rope and you bounce - the load on your pelvis is reduced significantly by the stretch in the rope absorbing that energy.

That said, it doesn't change the application as Bulli describes - start slowly, especially if using shackles and anchor points of limited trust. I would be wary of a snatch from a tow ball too - their load rating is static, not dynamic. It's worth noting that military vehilces (armoured and Landys) generally have some significant anchor points for recovery fitted, unlike a lot of civilian machinery.

Oops, hysteresis, nearly forgot; the kinetic energy you get out the rope will be much less than the energy you put in because of micro-heating of the rope fibres. So again, the recoil of the rope isn't all that large a contributor for freeing the vehicle.

Also as Bulli says, I wasn't there so I'm not judging the posted video, only passing accross some of my thoughts.

Hope some of this helps!

Cheers
 8)
Eeyore

[mark.yellow.series.3]

thats the worst piece of recovery ive evrt seen :?
even a complete idiot can see that was going to end badly.
if that rope had hit someone it would of killed them instantly.
for !Expletive Deleted! sake people, think  about the forces your are exerting on your equipment, and if your struggling, stop, take a step back and think of a better way of doing it.

i watched a bloke do that with a steel wire, trying to recover a paj, it did the same, nearly tore thro the bonnet of his truck when it came back at him.

Please tell us what exactly is so bad about it ?

1, snapped rope
2,broke rear window
3, did not acually recover vehicle with that rope using that driving techneque
4,very dangerous

i thought it was obvious

[chris.hunt22]

I usually shout until someone comes along with a winch!!!, what the hell was that bloke doing that close with a recovery going on, could of been nasty, V. lucky all round!!! :shock:

[Mudmonkey]

:shock: And thats why i dont like kinetic ropes! Not putting any blame on anyone here but if your not 100% sure on what you your doing with a kinetic rope then dont!

[ben_haynes]

David - what was with the guy in the red RR hitting the Suzuki in another video you posted. Doesn't he like his truck or something?

If you ever meet him you will know it  :lol:  :lol:

[datalas]

the worst piece of recovery ive evrt seen :?

If only it was the worst that I'd seen :(

I think the awards for that have to be

"towing a vehicle out with the seatbelt"

and

"a snatch recovery of a 90 by wrapping the strop over the spare wheel on the back door"

[thumbs]

ive used kinetics for years now, never normally have more then 3 attempts at it! didnt know the rope had a knot in it.

he asked for assistance, didnt sound like he new what he was doing to be honest. was very sloppy everywhere, no way in a million years would you have got traction takeing up the strain 1st.

i aint gona winch out some random bloke thats come up to me, i explained that to him, when my 500 quid winch goes bang i foot the bill!!!!
mates is a diferent matter but no way to a stranger in them circumstances, if it was just a easy pull then its differnt. i certainly aint worried about useing or getting it dirty!

i had drove that section before hand and had to winch myself out, no one had drove it straight through, that i see allday.

rope brakeing was just one off them things, bloke said theyd broke one the week before so............

i have defo seen worse recoverys then that, was nothing wrong with that other then rope failure in my eyes! poor equipment maintenece at the most!

[stevegreen]

Sorry thumbs but if you think that you did nothing wrong there then that is really alarming :shock:

If you were undertaking the recovery then you are responsible for checking the equipment being used - if for no other reason then ensuring it is not likely to damage your vehicle.  I'm not necessarily talking about spending a long time checking every inch of a rope in fine detail.  But a knot in a KERR is pretty easy to see.  Failing to notice a knot in a KERR which renders the rope unusable is your fault.  If someone was seriously injured who do you think the Police would be talking to?

I am assuming that the rope belonged to the guy that was stuck but by your own admission he didn't appear to know what he was doing and you say you have been using KERR for years.

If you consult any of the KERR manufacturers, or major sellers or indeed look at the MOD instructions for use then you will see that your technique is exactly what is warned what not to do.

In my time in the military the use of KERR ropes was restricted to armoured vehicles only as misuse of them with soft skinned vehicles was an accident waiting to happen.

I don't want to sound like I have never made a mistake offroad.  We all make mistakes but you should face up to them and learn a valuable lesson.  Next time you might not get off so lightly.

[Range Rover Blues]

I think the name is missleading, Kinetic Energy, as Bulli and Eyore have said, the rops actually absorb a lot of the energy involved in stretching them.  I use mine a lot for towing, but I hate doing that drive-it-like-you-stole-it style recovery.  The best thing about a kinetic is that is will contract and keep some tension on, so if you are towing a vehicle and you yourself are struglling for grip, you don't get lots of small tugs on your towbar that stop you in your tracks.  They are also usefull for recovery with a hand-winch as you can store energy in the rope.


But all ropes have a breaking point.

[thumbs]

well at the end off the day you live and learn dont ya, all went tits up but no one was hurt thats the main thing!

no point getting up on high horse about it!

[davidlandy]

I must admit that seeing this recovery it looked no different from any other KERR recovery that I have witnessed.

I have never seen anybody use one these that just carefully takes up the slack then pulls gently.  

As for me - well I dont use one as I am biased towards straps!

[Mudlark]

I think it would be interesting to see some of the replyees do a KERR recovery just to see how they do do it themselves - like davidlandy I've only seen it done as per the video on more than one occasion and with different people.

I can't stand the stuff either and would prefer a rope/strap or winch on recovery

[Bulli]

no probs , whenever you fancy mate. I stand by everything i say and if you ask anyone who knows me im more than capable of backing it up. Im not some armchair offroader and neither is eeyore.

I am not saying im the great i am, and we all cock things up. I operate a simple policy when out..if it need doing i do it. I wouldnt have hesitated to get the winch out and try that and in those circumstances i think thats the most likely course of action.
My winch gets used very regularily. I know how it works and it is the second i have had on the truck. I also have a healthy respect for what can go wrong.
Im still to see you in action but as im marshalling a few of the scorpion rounds this year cant wait to see you showing em how its done .

[Mudlark]

Not knocking Bulli, just intrigued, we are all aware (sometimes) of how something should be done and then forget it in the heat of the moment, that's why I posed the question.


As for scorpion - it may be a possibility but later in the year - I have work to do first :lol:  :lol:

[davidlandy]

I think the main problem on KERRs is the lack of information. All of the recoveries I have seen using them seem to be with the vehicle giving it full welly and gunning it away.  And I have seen lots of recoveries.
 
When a new KERR is purchased where does it say how to use it?  I have seen many for sale and none of them came with instructions.

so in the absence of these instructions there is a high likelihood that the purchaser will copy how he/she has seen the others doing it.

maybe theres a good opportunity for somebody to write up a safe recovery process for use for club members?

[Mudlark]

I think the main problem on KERRs is the lack of information. All of the recoveries I have seen using them seem to be with the vehicle giving it full welly and gunning it away.  And I have seen lots of recoveries.
 
When a new KERR is purchased where does it say how to use it?  I have seen many for sale and none of them came with instructions.

so in the absence of these instructions there is a high likelihood that the purchaser will copy how he/she has seen the others doing it.

maybe theres a good opportunity for somebody to write up a safe recovery process for use for club members?

Try this http://www.difflock.com/offroad/bowyer/ropes2.shtml

[redneck]

I think the main problem on KERRs is the lack of information. All of the recoveries I have seen using them seem to be with the vehicle giving it full welly and gunning it away.  And I have seen lots of recoveries.
 
When a new KERR is purchased where does it say how to use it?  I have seen many for sale and none of them came with instructions.

so in the absence of these instructions there is a high likelihood that the purchaser will copy how he/she has seen the others doing it.

maybe theres a good opportunity for somebody to write up a safe recovery process for use for club members?

What about this article http://www.dborc.co.uk/goodwinch/ropes%202c.htm from what i understand David Bowyer is highly respected in all aspects of 4x4 instruction. The only thing i personally would question is his use of a towball as a recovery point  :?  Is this a good idea   :?:  :?

[redneck]

Beat me to it  :lol:  :lol:  :lol:

[davidlandy]

well reading that write up and seeing the pics I am even more confused now!

so what is the correct way?

[Bulli]

my only comment on that is go ahead. Follow that exactly but dont come running to me when your head leaves your shoulders.
After seeing his dvd i think i found a cure for insomnia.
Mudlark if you arent knocking,which you do seems to enjoy, then try putting things a little more clearly.
Like i said we all do things wrongly from time to time. I can remember being involved with an extremly long recovery(over 3 hours). The method that finally worked in extracting a stuck g wagon was 3 cars towing simultaniously. VERY DANGEROUS no doubt about it. But everyone involved talked it through, made the choice and anyone not directly involved was well clear.
The alternate would have been to abandon the truck, which was also discussed.
I would make the same decision again under the same circumstances. The only thing each of us has is our expierience and sorry to say but reading about life through the internet is no substitute for living it.
Thats why i go out with people i know who wont abandon me and are willing to graft and help each other out of a sticky situation.That is the thing i enjoy most about our chosen passtime - the friendships that have grown up as a result of my participation in my local club.

[Mudlark]

well reading that write up and seeing the pics I am even more confused now!

so what is the correct way?

The only thing I can point to is this

I designed and developed the Recoverline KERR rope in the mid eighties in conjunction with Marlow Ropes when they were looking for a recovery rope system for 'light skin' military Land Rovers. The British Army had been using KERR ropes for de-bogging 60 tonne Challenger tanks made from multi - plait 90mm dia (3.5 inch) nylon rope. Thetas some rope!

I do know that David Bowyer runs instructional off-road courses however I didn't know until tonight his involvement in KERR technology

So now you know who to blame