Hard shackles -Vs- soft shackles in 4WD recovery
Soft shackle versus hard (steel) shackle for 4x4 recovery operations: Which shackle do you use, and where to you use them to maximise safety and reliability?
Society has gone soft generally, and lately there’s even an upstart shackle on the scene. Softer, weaker, but in some ways also sexier. The soft shackle.
So: What’s really better? Hard or soft?
Several people have asked this question lately, and if you lack the time to watch the whole video the answer is: Hard shackles are better at 90 per cent of off-road recovery operations, but there is one significant scenario in which the soft shackle just eats the hard shackle for breakfast - and we’ll get to that at the end.
You can live without a soft shackle in your recovery kit - there’s a workaround for that particular scenario - but you should put four hard shackles in your recovery kit.
Two 4.7 tonne shackles and two 3.2 tonne shackles - the big ones are notionally ‘stronger’, obviously but the small ones fit into more physically space-restricted spots. And they’re both plenty strong, as you will soon see.
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Hard shackles -Vs- soft shackles in 4WD recovery >>
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PART ONE
Shackles came up recently, in the context of discussing factors of safety generally. These are essentially the margin between safe usage limits and catastrophic failure. Predictably, the comments lit up on this.
There’s two parts to this, right? First - the part about relative positives and negatives. Second - the part about myth-busting the bullshit of 4WD recovery. There’s a lot of that. See, shackles and other items - wire rope in winches, slings … things of that nature - are generally adapted from the hoisting industry (you know, cranes and such).
And the parts have been cobbled together to form a system for off-road recovery, which (kinda) works. If you take a shackle and a sling and a wire rope hoist and a hook, maybe a snatch block, you’re essentially looking at the load-bearing parts of a winch recovery.
And the way the numbers work, the way they are presented to you, and the bullshit claims made about some of the parts in particular - especially winches - needs addressing.
This is compounded by never really knowing what the actual loads are. See, if you want to put a tank under a giant crane, one generally knows exactly how much it weighs, and one can then put a hoisting package together so that the working load limit of each component is not exceeded. Recovery is not like that - there’s generally no way of knowing the loads.
It’s all quite confusing, frankly, if you don’t have engineering training or work in industry. So I’m gunna unpack some of that right now - the beer-garden physics of recovery.
For this report I got my Saber soft shackle from Sparesbox. About $60 - link in the description. I had a bunch of steel shackles lying around already. Who doesn’t? Steel shackles last (statistically) for eternity, which is almost as long as it’s been since I’ve had ‘it’ thrown at me with at least vestigial enthusiasm.
HARD & SOFT SHACKLES TO CONSIDER FOR YOUR RECOVERY KIT:
Links to the hard and soft shackles from Sparesbox, in the description. Full disclosure there: I’ll get a small commission if you purchase using those links. Sparesbox is a good, reliable operation based in Sydney - but they’re not sponsoring this episode. I bought the soft shackle myself, and this report is my honest personal opinion.
BRAIN STRAIN
Pet hate: “Strength” is a bullshit term, firstly, because it typically isn’t referred to in relation to something - when it breaks or when it’s safe to use it up to a certain point.
In the case of steel shackle versus soft shackle, the two designations of “strength” relate to exactly opposite things. When you look at 3.2 tonnes stamped on the small shackle and the 14,700kgs on the soft shackle, you’d look at the softer shackle and think it’s substantially stronger, even moreso than the big shackle.
I get how you might misconstrue this, but the 14.7 tonne rating for the soft shackle relates to when it starts to break. That’s its minimum failure load.
The hard shackles refer to the Working Load Limit, in industry. Having broken these kinds of shackles in a laboratory, I can tell you the factor of safety is about six or seven. So the baby shackle will break at around 20 tonnes. The large shackle will break at around 30 tonnes.
The WLL (working load limit) of the soft shackle simply isn’t stated. You don’t get that kind of data from the manufacturer.
Remember: There’s no standards or codes for 4WD recovery.
The steel shackle is also rated based on being used longitudinally, not laterally or ‘horizontally’, as you might describe it.
If you do use it laterally, the thread will strip out and the arms of the bow will arc outward and not have the same strength as opposed to being used longitudinally.
Typically, these shackles break on the edge of the thread on the pin because the V carved on the base of the thread acts as a load concentrator (in extreme situations, obviously).
Pro tip: Do not use a bow shackle laterally, only longitudinally, and do not be in the way when this energy is unloaded if a bow shackle, or soft shackle, breaks during a recovery.
If you want to think about when to use a steel or soft shackle, you have to think about the pros and cons.
We know the small steel shackle is stronger than the conventional soft shackle, in terms of failure point.
Cost:
It’s less than $20 for a steel shackle versus change from $60 for the soft shackle. Or there’s an even stronger 17-tonne soft shackle which gives you an even greater margin of safety.
Buoyancy:
Definitely a factor here, because a hard shackle will sink immediately in soft mud where a soft shackle will float on water or wet mud. However, the soft shackle will be far more inclined to simply float away if you’re not quick enough to recover it - and good luck not twisting your ankle on loose river rocks sprinting in your thongs.
Projectile risk:
This is a huge red-flag issue. If a soft shackle hits you at 100km/h in the head when it breaks, you’re probably gonna live to fight another day. Hard shackle hits you - it’s lights out, no afterwards. That’s the salient risk here.
So, do not put together a recovery kit with a likelihood of a shackle coming toward you at high speed - if yours is rusty, or bent or split in any way, throw it out.
Sharp edges:
Manufacturers of recovery points bolted up to your vehicle with a working load limit of about five tonnes, they have sharp edges in the context of load. They’re not razor sharp, but 90-degree edges laser cut and minimally radiused. If you put a soft shackle on one of those sharp edges, that is enough to cut them under high stress. The fibres of the soft shackle will fail earlier than their failure rating.
Warning: Make sure you check for damage under the sheath in case of frayed fibres, stretching etc. If it is damaged - bin it. Buy a new one. What you can’t see will kill you.
Overall durability:
Steel shackle wins every time. Soft shackles have a shelf life. The number of usage cycles you’ll put one through means it’s eventually gonna wear out.
Ease of use:
Both are pretty simple. With the steel bow shackle, put your hook or strap through the bow, screw up the pin, but do not use a tool to tighten the pin beyond finger-tight.
When you reach finger-tight, un-screw it half a turn. Because if you put 5t of load onto the mechanically-tightened pin thread, you’re likely to turn it even further under added load and you’ll never get it undone again.
The sheer in the pin is what holds the load.
Soft shackles have a tendency to pull the knot out, under extreme load. There are lots of cases where this happens, plenty of video out there.
So: Don’t use a damaged soft shackle, and make sure your application won’t break a steel shackle to avoid projectile risk.
Now you just need to figure out which situation suits which shackle…
L-R: Rookie, Master. In case you couldn’t tell the difference.
RISKY BUSINESS
Case for soft shackles:
No sharp edges
High projectile risk for hard shackle
Case for steel shackles:
Everything else.
BEFORE PROCEEDING
Consider every recovery situation with extreme caution.
PART TWO
FAILURE RATE
You need to consider the most common recovery scenario, with a snatch strap.
Firstly, snatch recovery is not an opportunity to be a ballistic dickhead. You need to be gentle. Otherwise you ramp up the risk of component failure, or injury to people, if something goes wrong.
In an environment of recovery with a snatch strap, you have a recovery vehicle, the stranded vehicle, a snatch strap and recovery points on both vehicles. In determining the projectile risk (to figure out which shackle to use), you need to find the weakest link in the recovery operation.
Typical recovery points are rated to about 5t working load limit - none of them say their failure limit of course. The 4.7t bow shackle will fail at 30t, snatch straps like the ARB product fails at a minimum 8000kg (8t, obviously).
The snatch strap is the weakest link here. And they typically fail at the eye, where the stitching pulls apart. It fails incrementally, it gives you plenty of warning.
In this situation, where the strap fails, (and just to be clear, at this point, nobody should be standing anywhere near the strap or the vehicles in the recovery operation), the projectile risk is low because the shackle is not the weak link. \
But the sharp edge risk mentioned earlier, that’s high because you’re using those lase-cut recovery points (most likely).
So hard shackle wins here.
If you come across another vehicle stranded and in need of recovery, but you find they don’t have proper recovery points, you’re certainly not going to turn them down of assistance out there, a thousand miles from Dingo Piss Hotel.
So you’re going to be forced to use their vehicle’s standard shipping tie-down points. Obviously this is less than ideal, but it’s the only option left to you. So it’s important to remember, again, be gentle.
But, if you have a tree protector strap, you can use this through both shipping tie-down, which will effectively half the load you put on each shipping point. But don’t use shipping points on a regular basis - that’ll end badly. The calibre of shipping points varies widely and you need to ethically help a stranger in an imperfect situation.
WINCHING
If you’ve bought your first winch and got yourself suitably stuck, winching is a common form of self-recovery.
You’ve got the cable, the winch, the tree, and you tree-protecting strap.
Pro tip: Don’t get too big a tree for the strap. Once the angle on the strap exceeds about 120 degrees, the load is out of control because of the vector fudge factor. Get the angle as acute (sharp) as possible.
A good tree protector strap is rated to about 12,000kgs, with two arms rated at about 12,000kgs also, minus the fudge factor for the vector, with about 20,000kgs of total load restraint capacity built into the strap.
The 4.7-tonne big steel shackle’s gonna fail at about 30,000kgs.
The cable’s pretty weak. A Warn Zeon 12S which is Warn’s premium 12,000lbs winch, with a 9.5mm cable fails at about 14,400lbs (6550kgs). So the cable is much weaker than any of the upstream apparatus here. But the cable’s kind protected by the winch because Warn knows how hard it’s bullshitting on the 12,000lb rating; they’re so misleadingly optimistic about what they can deliver.
Warn’s rating only technically deliver their maximum rating on the final layer of cable on the drum. As the cable builds up on the drum, the diameter increases and the mechanical advantage is reduced.
You also have to add that you need five wraps of cable on the drum because the only thing holding the cable on the drum is friction and the end-stop is not capable of holding any load. It’s only these five ‘dead wraps’ that hold the cable on.
On the most effective layer of cable you are unable to utilise five wraps, and on the Warn Zeon 12S Platinum, for example, you’ve got another 19 wraps to use, which equates to about 5.5 metres of useful cable - about one car length. That’s it out of 30m of cable, where you could hope to deliver 12,000lbs.
And at that point, you’re going to be pulling 450 amps out of the battery, pulling the line at about 3-5 feet per minute. So 3-5 minutes to drag the car its own length through a bog or past an obstacle, up the slope, out of the rut - whatever.
We are now in absolute fantasy here because the battery which can deliver 450 amps for five minutes is a deadset miracle.
So the winch is the first weakest link, due to is gross under-delivery.
The next weakest link, providing the battery doesn’t die and the winch stalls, is the cable. It’s not going to break the shackle, but you’d better have a ballistic protector blanket over the cable to arrest the recoil. Because that cable is elastic at this point.
Soft shackle is not going to help at this point, so again, stick with the hard shackle.
Also, if the tree gives way, don’t worry about your gear coming toward you because the tree is actually the thing to worry about.
GET THE PHYSICS RIGHT
Load restraint is something that does people’s heads in.
Typically, you’d think 12,000kg of load restraint plus 12,000kg on the other side of the strap going around the tree equals 24,000kgs pulling on the strap at the back of the tree.
Happily, it doesn’t. Thanks to Sir Isaac Newton’s third law of motion.
A 100kg man on the floor pushes down. 100kg of floor pushes back, otherwise man is going through the floor.
100kg man doing a chin up pulls down on the bar. The bar pulls up.
Your vehicle pulls on the winch cable or strap. And the strap/winch pulls back with exactly the same amount of load.
Using a tree protector is simply applying this same scenario between the vehicle and the tree and the strap.
In the case of the tree protector strap, it’s 12,000kg per side, but accounting for the fudge factor and angle, it’s 20,000kg of load restraint in play here.
You don’t have to understand or even agree, but you can still accept that it’s true. Because that’s how this works. #physics
SNATCH ‘N’ GRAB
Another hack you can do with physics, if you’re seriously stuck, is to use a snatch block.
Essentially, it’s just a pulley. You wind the cable out, go around the pulley, then anchor to the recovery point on your bullbar or vehicle chassis - wherever. What it does is double the effort or halve the load on the winch, essentially. But it does also halve your speed. Nothing’s free - laws of thermodynamics.
So you’ve still got your 20,000kg of load restraint capacity in your tree strap, you’ve got your tree still adequate (but not too big), your shackle can still stand 30 tonnes without breaking, your snatch block is different though because it has a sharp edge on it where the shackle goes through (so remember that), the snatch block has a minimum working load of 9000kg and fails at a minimum of 14,500kg (which isn’t much).
And then you’ve got your cable. The cable is the most likely piece to break, but long before that happens, the winch is going to run out of grunt. the battery will run out of grunt.
I can’t see the point of a soft shackle here.
The case for soft shackles has arrived.
If you’re monumentally stuck in sticky, sucky, wet sand below high-tide mark, where you need to recover a vehicle at great distance - because you can’t get too close - you can join a winch extension to your soft shackle.
The shock absorption of the snatch strap is high in this recovery. It’s made of nylon which loses stretch capacity when wet - so gkeep it dry - and in this situation, joining two straps together with a hard shackle is a bad, bad idea.
F = ma. There is an extreme projectile risk here using a hard shackle. You can simply loop your two straps together.
Or simply feed through your brilliant new soft shackle and you’re ready to begin your recovery and save Captain Quicksand from the jaws of the Indian/Pacific Ocean before the tide rolls in.
A very elegant solution indeed.
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