Snatch straps and dampers

[filcar]

Really shows the forces involved in a snatch recovery, and how useless dampers are if a shackle or recovery point lets go ...

https://www.youtube.com/watch?v=4sRebBY_muQ&feature=youtu.be&fbclid=IwAR2pOKsS-UlWZRVh2eCFVcbYKyvwNqrHvIaFEDnSUrk5FeikboKcbnPcdvs

[GGV8Cruza]

A great test that all should watch

GG

[paceman]

really interesting stuff... thanks for the link...

as someone who is just getting into more serious 4wd work, and just about to get a kit together, this was timely...

also, what was interesting was people in the comments talking about 'soft shackles'...

i had never seen these before...

do any forum members use these? 

[#jonesy]

Pretty scary stuff looking at that.
I haven't done any real hard recoveries, only a few simple ones on 4x4 courses.
Might get some soft shackles., How do they go on most recovery points that are flat steel?

[GBC]

Lesson of the day - never, never shackle a snatch strap. This has always been the case since we first started using them in the 90's but seems to have been forgotten over the years. Dampers were invented for winch cable, not snatch straps, and they go 2/3 away from the car to slow the cable down (somewhat....). Same principle on the snatch - if he had that chain wrapped at 1/3 length instead of at the end, the shackle would have dropped even better than it did.
The vid and it's approach was excellent though, and sobering. Always make sure that the strap is the weakest part of the system - flying metal kills.

[tryagain]

In regards to soft shackles, this video is worth a watch. The summary is basically NEVER use a metal shackle to join two straps and only use rated recovery straps. This should ensure that the scenario portrayed in the original video posted with flying metal never happens.

It would be interesting to see if a dampener makes much difference to the forces of a snapped strap as that I think that is the more likely scenario.

https://www.youtube.com/watch?v=kW304fXuG1M

[sparksy]

really interesting stuff... thanks for the link...

as someone who is just getting into more serious 4wd work, and just about to get a kit together, this was timely...

also, what was interesting was people in the comments talking about 'soft shackles'...

i had never seen these before...

do any forum members use these?

I made my own.   https://www.animatedknots.com/soft-shackle
Instead of the dampers or extension straps I made a extension "strap " out of about 20m of 12mm dyneema rope.  Able to shorten if needed by just doubling up. just use the soft shackles to join up.  Dyneema is very easier and safer to play with. A eye splice is only a matter of opening up the braid and feeding the end through a few times. https://www.animatedknots.com/brummel-eye-splice-knot

[Bird]

Nice read on joining straps etc.


http://www.whyalla4wd.org.au/Shackles.html

and some very interesting figures. I dunno if they are correct, but goes to show you how fast Shit can go wrong.

Determine Speed of Shackle if Snatch Strap Breaks.

If all the Elastic Energy of the Snatch Strap is transferred to Kinetic Energy in the Shackle then the peak Speed of the Shackle as the Snatch Strap returns to it's 9.0m length can be determined. (Assuming no losses due to friction)

From Energy Conservation,

    Elastic Energy in Snatch Strap = Kinetic Energy of Shackle
    PEStrap = KEShackle
    1/2 k x2 = 1/2 m v2
    where k = spring constant
    x = distance stretched (meters)
    m = mass of shackle (kg)
    v = velocity of shackle (m/s)
    1/2 (20750N/m) (0.579m)2 = 1/2 (0.68kg) v2
    v = 101m/s

    or Peak Speed of Shackle   v = 364 km/h

364kph= 101.1111m/s

[Merts]

also, what was interesting was people in the comments talking about 'soft shackles'...

i had never seen these before...

do any forum members use these?

Yep. They are terrific. Heaps lighter to carry and way safer to use.
You can even use them to join straps as they are no heavier than the straps themselves, whereas steel shackles are a potential missile.
Straps can be joined by threading each strap through the other strap loop, but this is a bit time consuming and can result in the straps becoming permanently joined. Using a soft shackle is much quicker and just as safe.

[paceman]

Yep. They are terrific. Heaps lighter to carry and way safer to use.
You can even use them to join straps as they are no heavier than the straps themselves, whereas steel shackles are a potential missile.
Straps can be joined by threading each strap through the other strap loop, but this is a bit time consuming and can result in the straps becoming permanently joined. Using a soft shackle is much quicker and just as safe.

so, i could use a couple of them to secure a bridle to the front points of the pajero, in the case of a recovery... ?

have also been looking at the kinetic rope, rather than the snatch strap... makes for interesting reading...

[Troopy_03]

When you join straps by threading through each others eyes, you need something to stop them becoming locked together. We've used this method before, with good success.

https://www.youtube.com/watch?v=qV9lr6hBXJg

[Bigfish]

so, i could use a couple of them to secure a bridle to the front points of the pajero, in the case of a recovery... ?

have also been looking at the kinetic rope, rather than the snatch strap... makes for interesting reading...

You certainly can.  As you know, the 2 front recovery points on a Pajero require a bridle to spread the load evenly. Soft shackles with a protective cover to stop chaffing or cutting is required.

[austastar]

Hi,
   Check out
Bubba Rope.
for something that will really store energy.
Cheers

Sent from my SM-T380 using Tapatalk

[paceman]

Hi,
   Check out
Bubba Rope.
for something that will really store energy.
Cheers

Sent from my SM-T380 using Tapatalk

that's the one i was looking at...

[MrCruza]

that's the one i was looking at...

Ironman have released one similar, rated to 9500KG

[silverfox1111]

I've got a couple, but haven't used them yet.
As asked above, what are people's thoughts on a soft shackle going through a recovery point with its sharp 90° edges.
Silverfox

[Bird]

Looks like it may come apart easily, but will wait till I look at em in the flesh on weekend.

[tryagain]

I've got a couple, but haven't used them yet.
As asked above, what are people's thoughts on a soft shackle going through a recovery point with its sharp 90° edges.
Silverfox

It's covered in the video I linked above, long story short is that they are apparently quite susceptible to damage so probably not ideal. A bow shackle in this situation is perfectly safe though as it has a much higher minimum breaking strain than the strap, so every time it is going to be the strap that breaks first and the shackle will stay in place. A soft shackle doesn't really offer any advantages (apart from some weight saving) in this situation.

[Hoyks]

Yes, in order to to eliminate the risk its not recommended to use shackles in the snatch strap set up and certainly never to join them, but rated shackles are manufactured and rated for lifting, so have a yield strength that is much higher than the failure point of a snatch strap and all the the other bits in the setup. 

How often you hear of a rated shackle actually failing in a recovery?
I haven't, I have heard about bits of the vehicle being torn off and plenty of straps snapping, but not shackle failure.

Soft shackles are a nice idea, but the 'rating' of them appears to be very close to the breaking point, so I'd be careful with them too.

Not a bad test.
https://www.youtube.com/watch?v=66BXmM_JuBI

[Merts]

Looks like it may come apart easily, but will wait till I look at em in the flesh on weekend.

I've used them. They don't (and can't really) come apart under load.

[weeds]

Yes, in order to to eliminate the risk its not recommended to use shackles in the snatch strap set up and certainly never to join them, but rated shackles are manufactured and rated for lifting, so have a yield strength that is much higher than the failure point of a snatch strap and all the the other bits in the setup. 

How often you hear of a rated shackle actually failing in a recovery?
I haven't, I have heard about bits of the vehicle being torn off and plenty of straps snapping, but not shackle failure.

Soft shackles are a nice idea, but the 'rating' of them appears to be very close to the breaking point, so I'd be careful with them too.

Not a bad test.
https://www.youtube.com/watch?v=66BXmM_JuBI

My thoughts as well.....I have no issue using metal shackles at each end of a snatch strap and to a solid point on my car. The other car when you don’t know the person and or their set up is the worry.

There is an old saying to use the stick person recovery gear....Er no thanks.

I rarely use a snatch strap these days, I have frustrated two punters as I choose winching them over using a snatch strap.

Beach recoveries with a snatch strap would probably equate to 90% of all snatch recoveries.....tyre pressures generally eliminates the majority and a maxtrax or two gets most of the remaining. My number one rule is if the punter doesn’t want to lower his tyre pressures (using a gauge) than I leave the recovery to somebody else.


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[Rumpig]

Looks like it may come apart easily, but will wait till I look at em in the flesh on weekend.

jump on YouTube and watch the latest Drifta video series where he goes to Cape York if you want to see them used in anger, he uses his numerous times in the videos, snatching and winching and even anchoring his vehicle to a tree whilst winching a very bogged Cruiser and trailer.