The 4WD industry is plagued with the marketing of products that people don’t really need.
Often, these unnecessary products are marketed as “essential”.
So when kinetic ropes started becoming popular, I was sceptical.
Touted as more effective – and possibly even safer – alternatives to snatch straps, the bullshit-propaganda machine started telling everyone they needed to go out and swap their snatch straps for kinetic ropes. The biggest red-flag for me, was the fact that most people never even use their snatch straps, yet they were being told they needed a much more expensive upgrade.
I’ll tell you upfront that for the vast majority of people that already own a snatch strap, it’s probably not worth going to the hassle and expense of changing.
With that said there are significant benefits to kinetic ropes compared to snatch straps. But for most people, these benefits won’t justify the expense of replacement.
If you don’t already have a snatch strap, that changes the equation. Without the sunk cost, it could likely be worth buying a kinetic rope from the get-go. Keep reading to see what the differences are, and whether this might apply to you or not.
What Kinetic Ropes and Snatch Straps Both Do
If you use a normal strap or rope – no matter how strong- to try and recover a bogged vehicle, it wont be a pleasant experience.
Either:
You have to start towing very slowly, so that there’s no abrupt forces on both vehicles, which will probably lead you to become as bogged as the vehicle you’re trying to recover.
OR, you take off quickly while there’s still slack in the rope. And once the rope becomes tight you either smash your head into the dashboard/steering-wheel, or damage at-least one of the vehicles because of the abrupt forces. Most likely you’d snap the rope and still do some damage.
When you’re using a dynamic/elastic rope, such as a kinetic rope or snatch strap, you don’t get these abrupt changes in acceleration. Because the rope can stretch, it gives the towing vehicle a few seconds to slow down as the rope stretches. As opposed to the rope not having any “give” and you coming to a stop instantly.
Calculating the Forces During a Snatch/Kinetic Recovery | Why a Dynamic (stretchy) Line Makes a HUGE Difference
Year 11 physics reminds us that force = mass x acceleration.
The mass of either vehicle (the towing vehicle or the bogged vehicle) can’t be changed in this equation.
Therefore, the acceleration is the single multiplying force we can control.
For the sake of my lack of mental maths, let’s come up with a very simple – and completely arbitrary – hypothetical situation:
We’re in a 3 tonne Landcruiser that’s recovering a bogged Nissan Patrol (or for the sake of argument, a completely broken-down Land Rover or Jeep). To keep it easy, we’ll assume the Patrol is fully-loaded and also 3T.
And let’s say we get the cruiser up to 36km/h before the rope/strap goes tight, because that equates to an easy 10m/s (metres per second).
If we were using a static line, it would wipe off the speed from the towing vehicle very quickly. So we’ll say it takes the cruiser from 36km/h to 18km/h in half a second. This means that if the line hasn’t snapped, the Patrol has gone from 0km/h to 18km/h in half a second. In reality, with the friction and resistance from being bogged, we’d see the cruiser lose a lot more speed than the patrol would gain, but this is just to keep the maths easy.
The 18km/h difference between the starting speed (36km/h) and the speed the cruiser is reduced to when the rope goes tight (18km/h) is 5m/s (metres per second) over a space of half a second (0.5).
5/0.5 = 10. So that gives us an acceleration of 10(m/s)2 (metres per second, per second. The 2 is supposed to be in superscript indicating that it’s square, not multiplying by two, but writing like that is just too hard).
So getting back to force = mass x acceleration:
3,000kg multiplied by the acceleration of 10(m/s)2, we get 30,000.
If we ignore the devastation of being involved in a 30 tonne force, who is driving around carrying a static rope that’s good for a 30T breaking strength?
Now, if we’re performing the same recovery but with a nice stretchy kinetic rope, we could reach the same speed, but because the rope has a whole bunch of stretch/give, it might bring us down to the final speed over 2 seconds, rather than half a second.
It doesn’t sound like a lot of time, but when it’s the multiplying factor, it makes a big difference.
It’s now a change of 5 metres per second, over the space of 2 seconds: 5/2 = 2.5 giving us an acceleration of 2.5(m/s)2.
3,000 x 2.5 = 7,500
7.5T is well within the limits of your average 12T snatch strap or kinetic rope that are sold for 3T vehicles and importantly is far less stress to the vehicles and risk to the passengers.
We’ll get into the nuances below, but the key difference between a snatch strap and a kinetic rope is that the kinetic rope has more stretch in it. A snatch typically has 15-20% stretch capacity and a kinetic rope typically has 30-35%. To keep things simple, we’ll say that the kinetic is twice as stretchy.
So if the above example is a kinetic rope over 2 seconds, we can say that a snatch strap would do the same recovery over 1 second. 5/1 = 5. 3,000 x 5 = 15,000.
a 15T force is obviously too much for a 12T strap. So in this example, you’d either need a bigger/stronger strap or perform a slower and less effective recovery.
15T is more force than any of us want to be using for a recovery, so you would have to go a lot slower.
And I will reiterate that 36km/h is a lot faster than you would want to be going for a bogged 4WD recovery. It was just the easiest to visualise as it worked out to a convenient 10(m/s)2.
What is a Kinetic Rope?
A kinetic rope is simply just a rope that stretches under load.
Marketing based product descriptions would probably elaborate and embellish on that by saying a kinetic rope is a specialised recovery tool designed for off-road. Unlike traditional tow straps or static ropes, kinetic ropes are engineered to stretch under load, storing and releasing energy to create a “snatching” effect.
But basically, just a stretchy rope. Why and how that works for recovering a bogged vehicle is described ad nauseum in the section above.
How Does a Kinetic Recovery Rope Work?
Kinetic ropes get their dynamic nature from two key features: The material as well as the construction design. Unlike snatch straps, which just get it from the material.
Kinetic ropes use nylon, which inherently has a natural amount of stretch. Nylon will stretch beyond 30%, but there’s a point where if you stretch it too much, it wont return to its original length and is permanently damaged.
Kinetic ropes will typically utilise a hollow braid for their construction.
The rope is tubular, with fibres braided in a loose, open weave. This allows the rope to compress and expand like a spring, enhancing its stretch.
But aside from simply giving it more stretch, it also serves to protect the nylon from over stretching. The initial part of the “stretch” comes from the rope tightening and squeezing itself, which provides some stretch without stretching the fibres. If you can imagine that each strand is like looking at a sound wave or any sine wave, as the braid pattern means that the strands go up and down and not in a straight line. If you can imagine taking that sine wave and straightening it out, it will span over a greater distance.
As the kinetic rope gets pulled, it will continually tighten on itself until there’s no empty space left within it and it can’t be compressed. This is another form of stored energy. This absorbs some of the initial force in the recovery, before the force results in the fibres stretching.
The braid also contributes to the load being distributed more evenly, without twists or concentrations.
Key Features of Kinetic Ropes
Kinetic Ropes are Reusable | No Rest Required
Snatch straps don’t return to their original length instantly.
I don’t know if it’s because their tight weave creates a lot of friction between fibres when stretched, or if it’s just the nature of polyester (or both).
As a general rule, you’ll only get two attempts out of a snatch strap, before you need to let it rest for up to 24 hours. If you don’t, it will be less effective and create a lot more shock-loading. Not to mention, damage the strap and risk breaking it.
Kinetic ropes are good to go again, straight away.
A key advantage to this, is that it lets you start out at lower speeds, because you have a few more tries up your sleeve. This way you can work your way up to a sufficient speed, without having to over compensate. As I’ve mentioned several times already (and will again throughout the article), the more you can minimise the force and the shock loads, the better.
Some people also argue that you only get 5 to 6 good recoveries from a snatch strap, before it needs replacing. I’m not sure I completely agree with this. I’ve got snatch straps that I’ve used 5 times that I’m comfortable using again, but this isn’t considered best practice. A kinetic rope will be good to use again and again so long as it hasn’t been over stretched or damaged.
Kinetic Ropes Stretch More
As mentioned above, the key feature of a kinetic rope is that it has more stretch than a snatch strap. This provides several benefits:
More Successful Recoveries
Because it stretches more, it can store more energy. Not only is this an efficiency boost, but it means you can go faster in the towing vehicle, without putting undue forces on either vehicle. This means you will have a higher chance of recovering the bogged vehicle per attempt.
It might sound a bit extreme, but I’m sure you wouldn’t be using a snatch strap or kinetic rope if the car wasn’t really stuck.
Reduced Shock Loading | Less Risk of Vehicle Damage
Assuming you went at the exact same speed for a snatch strap recovery versus using a kinetic rope, the shock loading on both vehicles will be significantly reduced.
If you skimmed the bit about calculating the real forces involved, revisit it to see just how much the extra time, reduces the acceleration.
It’s important to know that it doesn’t reduce the force of the overall recovery (which would make it less effective), it just increases the amount of time this occurs over. This significantly reduces the acceleration upon the rope going tight, which is the same as saying it reduces the shock load. This is important not just for driver/passenger comfort/safety, but also for not damaging either vehicle.
You Can Use a Higher Load Rating and Have a Larger Tolerance
It’s pretty obvious that if you use a strap or a rope that has too low of a rating, that it’s a bad idea. It could break. And as we’ve discussed in the forces section, they’re storing a hell of a lot of energy, so this can be very dangerous.
What’s maybe less obvious, is that you can also come unstuck (pun intended) by having too high of a rating.
If you use a 100,000kg snatch strap or kinetic rope (which you can actually find for agricultural purposes) for a 3T car, it’s not going to stretch at all.
But, it’s also not going to break. Meaning, that all 30,000kg of force from the calculation earlier in this article, are going to be applied to you and the vehicles. Not good.
So it stands to reason that there’s a sweet spot somewhere, that achieves a high enough strength to avoid snapping or over-stretching, but not so high that it isn’t stretchy enough for the use-case. Most manufacturers go for 3-4x the weight of the car being recovered.
If you use an 18T kinetic rope for a recovery that warranted the use of of a 12T rope, it probably just means that you’ll get the kind of performance that you would have gotten from a 12T snatch strap. Not the end of the world. But if you use an 18T snatch strap for a recovery that called for a 12T strap, it may be a problem. You’re going to have a lot more shock loading, and a less successful recovery.
Kinetic ropes simply give a bit more wriggle room. If you don’t know what your vehicle weight will be when it’s loaded – or perhaps you sometimes tow a trailer but not always – or you can’t expect to know the weight of a vehicle that you might be recovering, a kinetic rope has a greater margin.
More Gentle on Soft Shackles
I might be clutching at straws with this one, but nevertheless it is a theory that I have.
The loop at the end of a snatch strap, provides a rectangular/flat surface where you would put a soft shackle around it.
It might be reasonable to assume that it would conform and bend to the shackle, but with several tonnes of force being applied to the strap on a plane that opposes such bending/conformity, I’m inclined to think it would actually hold its shape.
This means that the soft shackle is being bent around the “corner” of this part of the strap. And it is a fact that the fibres used in soft shackles shouldn’t be under load over certain angles, otherwise their performance degrades and they get damaged.
A kinetic rope will provide a round surface for the soft shackle to conform to, where the bending angles aren’t as extreme as the snatch strap.
Downsides/Cons of Kinetic Ropes
More Easily Damaged
Less Abrasion Resistant
Nylon is simply more prone to abrasion than polyester. But also, as kinetic ropes have a loose braid, it’s easy to get things caught between the strands when it’s loose, that can then cause damage once it’s gone tight. It can also be a problem if the rope gets used in mud, as sand and other grit can get between the strands and abrade it from the inside.
This just means that you need to be more careful about rocks, parts of the vehicles, mounting points etc and also means you should keep it stored in a bag.
UV Damage/Degradation
Nylon is more sensitive to damage from sunlight, compared to polyester which is used for snatch straps.
This is another reason to keep it in a bag, when in storage.
Heavier and Bulkier
Kinetic ropes do take up more space than a snatch strap rated for the same loads.
And they’re just not as convenient to roll up. A snatch strap can easily be rolled up and is always the same size when you go to put it into a bag. For some reason, kinetic ropes are like tents and I have no idea how to get them back into the same bag they came in.
More Dangerous if it Goes Wrong
A lot of people do go on a bit about how kinetic ropes can be more dangerous in the event of a failure or breaking attachment point.
While this is true, I think of it as being a feature rather than a bug.
The whole point of a kinetic rope compared to a snatch strap, is that it stores more force. Therefore, if something does go wrong, the stored energy that can catapult lethal missiles at you is greater.
But make no mistake: Snatch straps are perfectly capable of killing people. So you need to take suitable precautions no matter what you’re using.
More Expensive
Kinetic ropes are significantly more expensive than snatch straps.
Please see the section below on cost.
What is a Snatch Strap?
For the ‘what is a kinetic rope section’ I wrote:
“A kinetic rope is simply just a rope that stretches under load.
Marketing based product descriptions would probably elaborate and embellish on that by saying a kinetic rope is a specialised recovery tool designed for off-road. Unlike traditional tow straps or static ropes, kinetic ropes are engineered to stretch under load, storing and releasing energy to create a “snatching” effect.
But basically, just a stretchy rope. Why and how that works for recovering a bogged vehicle is described ad nauseum in the section above.”
If you just swap every mention of ‘rope’ to ‘strap’, that pretty much sums it up.
How Does a Snatch Strap Work?
The stretch in a snatch strap comes purely from the material, unlike kinetic ropes which also get part of their elasticity from the braid.
Snatch straps are a flat webbing in a tight weave – much like a seatbelt – and are most often made from Polyester.
The flat webbing design is purely for strength and load distribution. All of the elasticity comes from the nature of the polyester.
Polyester stretches up to 15-20%. It is not as stretchy as the nylon used for kinetic ropes, but is less prone to over stretching.
Key Features of Snatch Straps
Durability and Longevity
Snatch straps are much more abrasion resistant than kinetic ropes.
They are far less prone to UV damage.
A snatch strap will last longer than a kinetic rope, if the kinetic rope is not stored carefully.
Storage – More Durable and Less Bulky
When it comes to a typical 4WD owner that wants to have either a kinetic or a snatch as a “just in case” but isn’t likely to ever use it much, a snatch strap becomes the better option for throwing it in the back of the car somewhere out of the way. Their hardiness and more compact nature, mean they can be tucked away somewhere and not checked on again.
Better for Towing
A snatch strap provides for a much better towing experience than a kinetic rope.
It’s stretchy enough so that every time you get slack in the strap and then it tightens again, it’s not as jarring as a static line.
But it’s not so stretchy that you get an aggressive yo-yo effect like you do with a kinetic rope.
If you do find yourself towing with a snatch strap and it is a bit too bouncy, you can just double it over if the length allows (or if you have a static tow rope you can attach it to).
Cheaper Than Kinetic Ropes
Snatch straps are significantly cheaper. More on that in the cost comparison section below.
Downsides/Cons of Snatch Straps
Snatch Straps Don’t Stretch as Much as Kinetic Ropes
This is the key difference and pretty much the only reason there’s a market for kinetic ropes.
Snatch straps are generally more convenient for their durability in storage and their price. They’re just not quite as good at getting the job done.
Greater Risk of Vehicle Damage
Because they don’t stretch as much and cause more shock loading, there’s a greater chance you’ll cause damage to one of the vehicles.
Twisting
Because snatch straps are flat, they become twisted very easily. You need to make sure you connect it between the cars without any twists.
They will still work if twisted, but you increase the chance of damage.
Less Reusable
After 2 attempts, snatch straps need to be left for up to 24 hours, to return to the original length. This is not the case for kinetic ropes.
Chance of Permanent Deformation
After multiple serious recoveries, snatch straps become permanently stretched and unfit for purpose.
But, it’s not the case for small recoveries.
A lot of times you might be in a position where the car needs a bit of encouragement to get out, but not a full-on hell-for-leather snatch recovery. I’m confident that you can do many small recoveries without deforming the strap.
The 5 to 6 recommendation you might hear sometimes, I think applies only to bigger recoveries.
Cost Comparison
A cheap snatch strap can be found for under $100.
A cheap kinetic rope sometimes can’t even be found.
The 4WD Supacentre did release a cheap kinetic rope. If I recall correctly (because I haven’t seen one in quite a while), they were released under the Hercules brand and came with soft shackles.
But the reason I haven’t seen one in a while is because they were recalled, because they were snapping. And – allegedly – in testing were only showing a stretch of around 8%.
It’s still hard to find a cheap kinetic rope, nor do I believe that you should. I’m sure it’s only a matter of time before increasing mass production and falling per-unit costs bring us safe and reliable kinetic ropes for cheap, but we’re not there yet.
A decent kinetic rope is going to cost you over $300 for the rope itself. More if you want it in a kit with soft shackles, bridle etc.
When to Use a Kinetic Rope vs Snatch Strap | Which One Should You Buy?
If you’re doing a lot of touring but not planning on deliberately doing anything tricky, then a snatch strap is probably your best. Likewise if you’ve got a 4WD that only sees basic or occasional off-road use, but you want to be covered just in case.
A snatch strap is cheap insurance.
The key benefit to a snatch strap (other than the price), is that you can throw it somewhere in the back of your car and not think about it again. Because they’re so much more durable in terms of abrasion resistance and UV exposure, they’re much better suited to a set and forget approach.
If you think you’re likely to need to receive or perform a recovery – particularly more than once – than a kinetic rope is the way to go. It’s the better tool for the job, but is more expensive and needs a bit more care.
If you’re weekend bush-bashing with your mates, or heading to the Cape or Canning Stock Route, someone in the group should have a kinetic rope.
If you are just heading out for weekend trips that are more about the driving and less about camping – meaning that efficient storage isn’t paramount – then why not have both?
When to Avoid a Snatch Strap or Kinetic Rope
Any time you’re doing something that’s supposed to just involve static lines, you should not introduce anything that can store energy.
Winching is the most common example of this. Most often seen when someone uses a snatch strap as a winch extension or two wrap around a tree.
Modern synthetic winch ropes do a very good job of not storing energy. If you’ve ever seen a winch rope snap, it probably just fell to the ground.
Because of this, if something in the sequence breaks – like a winch hook coming loose for example – it doesn’t become much of a dangerous projectile.
But as soon as you introduce a dynamic component such as a snatch strap, you now have every part of the sequence subject to dangerous amounts of stored energy.
What compounds the risk, is that the snatch/kinetic will usually be stronger than the static components such as the winch rope. This means that it is more likely for the winch rope to break, leaving the snatch/kinetic in-tact to direct all of the force into something heavy like a winch hook.
FAQs About Kinetic Ropes and Snatch Straps
Can You Reuse a Snatch Strap After Recovery?
Yes, but they are typically only good for two recoveries before they have to be left for a day to return back to their original size.
Snatch straps also only have a limited amount of recoveries before they become permanently deformed.
How Much Stretch Does a Kinetic Rope Have?
Most good kinetic ropes should stretch up to 30%.
Are Kinetic Ropes Stronger Than Snatch Straps?
Not necessarily. The difference is how much they stretch, not the strength. You can get snatch straps and kinetic ropes for different rated breaking strengths.
Can You Use a Snatch Strap with a Winch?
No. You should never use anything that can stretch (and therefore store energy) in a process that is supposed to use static lines (ropes that don’t stretch).
How Do You Store Kinetic Ropes and Snatch Straps?
Snatch straps can be dragged underneath a tractor crossing the entire Simpson Desert, but kinetic ropes should be stored on pure silk inside a cushioned box that has been purged of all oxygen and replaced with argon gas.
Snatch straps are pretty hardy. But with that said, you should keep them in a place that isn’t exposed to direct sunlight for any extended periods of time.
Kinetic ropes should be kept in their own bag and should be free of mud, sand etc before going in the bag. The bag shouldn’t be see-through to keep the sun out.
