Kinetic/snatch ropes and straps for Jimny

I have been investigating the wide topic of Jimny recovery recently.

Among other things, there is a question of what strength and length of a kinetic rope or a snatch strap would be adequate for a Jimny.

I compiled information from various world wide sources (Britain, Germany, USA, South Africa, Australia, Russia).

I came to several uncertain conclusions:


1. Naming

The elastic ropes and straps which are used to recover bogged/stuck vehicles are called either "kinetic" or "snatch", depending on the world region. Therefore, a kinetic rope and a snatch rope is the same thing. Also, a kinetic strap and a snatch strap is the same thing.
In some regions abbreviations "KERR" (Kinetic Energy Recovery Rope) and "KESS" (Kinetic Energy Snatch Strap) are also used.


2. Advantages of rope over strap

In general, a kinetic rope is more elastic than a kinetic strap, and therefore provides better dynamic response in the critical moment (important for very bogged situations). Also, a rope should be slightly more durable.
Does anyone know of other possible advantages?


3. Advantages of strap over rope

In general, a kinetic strap is much cheaper to make than a kinetic rope (3-5x difference).
Also, when folded, a strap takes much less space than a rope of equal length. This is important for Jimnys.
Does anyone know of other possible advantages?


4. Load rating

A rope or a strap MUST have a load capacity rating. It appears that MBS / MBL ("Minimum breaking strength" or "Minimum breaking strain" or "Minimum breaking load") is the industry universal rating for load capacity.
Other parameters which I found are "SWL" (Safe Working Load) and "WLL" (working load limit), which are typically much lower than MBS/MBL, but MBS/MBL appears to be the most commonly used.


5. Length

What length would be minimal/optimal?
Various lengths of kinetic ropes and straps are available on the market. The minimum which I found is 4 m, while it appears that lengths between 6 m and 10 m are the most common.

Some sources suggest that the length between 9 m and 10 m would be optimal - supposedly anything shorter than 9 m does not provide enough "takeoff" space when engaging the recovery.

However, if you need to operate in tight spaces, wouldn't 9-10 m be too long? Would something like 5-6m be better suited?


6. Optimal MBS for Jimnys.

This is the most disputed topic.

In general, as bad as it is to use a too weak kinetic rope or strap (as it could break), it is also bad to use a too strong one, as it will not experience a heavy enough load to stretch properly, acting just like a regular non-elastic tow rope, which would shock-jolt the vehicle.

Therefore, the question is which MBS range would be optimal for small Jimnys.

I read in several sources that MBS of a rope or strap should be two to three times higher than vehicle's GVM "Gross Vehicle Mass". Supposedly, when MBS of a rope or strap is 5x GVM or more, it is "too strong".

The GVM of a Jimny is around 1400 kg. According to that, you would need a rope or strap rated approx. between 3T and 4T.
However, most kinetic ropes and tow straps are rated for 8T and 12T MBS. Many manufacturers advertise their 8T products as being for "light 4x4/4wd vehicles - a vague description.
The few 3-4T ropes and straps which I found are all advertised as being for "ATV applications".

Therefore, there is an obvious discrepancy between MBS/GVM guidelines from some sources and recommended product applications from some manufacturers.
I would appreciate help in clarifying this, and also some information about specific brands and products (ropes and straps) which are optimal for Jimnys (and SJs and Vitaras and similarly sized vehicles).


EDIT:
An example resource:
www.juststraps.com.au/pdf/Snatch%20Strap...%20Amended%20pdf.pdf

Thanks for this, can I just add in some comments:

Kinetic ropes and straps are banned on many UK off-road sites due to the danger in using them. The strength of the anchor points on both vehicles is vital to the operation. As stated many ropes are around 8Ton or 12Ton working strength but the key is that they are "kinetic" which is Mass x velocity so although your vehicle may be 1.4ton the energy is also dependent on the speed. At the point of maximum stretch the energy is transferred to mounting points of the strap.

I have personally seen:

1. The towball of the vehicle performing the recovery go back through the windscreen of the stuck vehicle
2. The entire front bumper and chassis rail section of a stuck vitara come straight off.

Take care with kinetic ropes, they were designed by the British Army to recover stuck tanks.

www.goodwinch.com/Learning/ropes-for-towing-heavy-pulling/

also if your the stuck truck make sure your head is fully back touching the headrest
as you can't claim whiplash in a recovery situation LOL

Jack

I would never use one. I have seen a shackle launched through the back window of a
Discovery, only just missing the driver.

All your warnings about the dangers of using kinetic ropes and straps are absolutely valid.
Kinetic ropes and straps are so dangerous that those warnings can never be emphasized enough.
However, I did not mention the dangers in my original post as the text was large enough anyway.


Here it is now:

I suppose that most of you played with elastic bands in your youth. If you overstretched them until one snapped back to your fingers, then you know very well how much that hurts! A small band hurt like an ancient Egyptian whip.

That amount of pain was caused by the relatively large amount of potential energy which was build up in the small stretched band. That energy got released in a whiplash effect when the band snapped.

The same process happens with the kinetic rope or strap, as they are elastic. When they stretch under load, they accumulate very large amounts of potential energy. The additional problem here is that instead of having your fingers holding the stretched rope/strap, there are vehicle tow points or shackles holding them. Therefore, that energy from the rope/straps then gets applied to the vehicles' metal connection points.

So if a rope or strap breaks under tension, or (much worse) if the metal recovery point itself breaks (this is much more likely with unmodified vehicles!), it will be sprung back like a giant whip with a vicious metallic banger at its tip. It hardly gets more brutal than that.

Therefore, kinetic recovery is a process only for those who are trained and equipped to do it. The important thing to always have in mind is that both vehicles involved in a kinetic recovery must have adequate (rated) recovery points which are properly installed. If that is not the case, than it's a dice with high stakes.

I personally know of another damage caused by kinetic recovery - a bent chassis on an offroading competition Pajero.


Now, having all these dangers taken into consideration, what would be the others' comments on my uncertain conclusions from my original post?

P.S.:
Here is a very informative discussion from a South African forum:
www.hilux4x4.co.za/views/viewtopic.php?f...28bddf8c1e5ad7b7437b

I don't believe there is a genuine need for kinetic rope recoveries in any recreational off-road scenario, least of all with a car as light as a Jimny. Like most things off-road, everyone likes to think they need all the fancy kit. A stuck 4x4, a group of testosterone riddled men and a kinetic rope is a bad mix. A little bit of lateral thinking and careful persuasion is a much more effective tool.