MySwag.org The Off-road Camper Trailer Forum
General => General Discussion => Topic started by: Patr80l on March 18, 2018, 02:28:57 PM
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https://www.brisbanetimes.com.au/national/queensland/man-killed-by-snapped-towing-strap-as-he-was-helping-bogged-driver-in-central-queensland-20180318-p4z4x1.html (https://www.brisbanetimes.com.au/national/queensland/man-killed-by-snapped-towing-strap-as-he-was-helping-bogged-driver-in-central-queensland-20180318-p4z4x1.html)
Avoidable?
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Likely very avoidable...but without knowing what broke and why, it's hard to say really for this situation. Sadly many people think snatch straps are a right pedal to the floor recovery device, but if they deflated their own tyres more and remembered it's a giant elastic band basically that doesn't need speed to work, then many of the deaths or injuries that have happened would have been avoided.
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Likely very avoidable...but without knowing what broke and why, it's hard to say really for this situation. Sadly many people think snatch straps are a right pedal to the floor recovery device, but if they deflated their own tyres more and remembered it's a giant elastic band basically that doesn't need speed to work, then many of the deaths or injuries that have happened would have been avoided.
Exactly.....every 2nd snatch you see on video is done at a speed that isn't needed.
95% of recoveries only need a tow, but some seem to think once that strap goes on, a snatch is the go ?
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Exactly.....every 2nd snatch you see on video is done at a speed that isn't needed.
95% of recoveries only need a tow, but some seem to think once that strap goes on, a snatch is the go ?
Many also fail to use an appropriate dampener in case of breakage.
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Many also fail to use an appropriate dampener in case of breakage.
The recommended safe method is two (2) dampeners. One at each end, a metre from each attachment point.
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A snatch strap by itself going through a laminated window and keep enough momentum to kill someone.
Really?
I can't help but think something shaped like a letter "D" was on the end of that as well......
What a sad incident for everyone.
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Watching a video from RV Daily about snatch straps as I'm reading this. Maybe more people should watch more.
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The recommended safe method is two (2) dampeners. One at each end, a metre from each attachment point.
Thanks Charlie Brown, did our 4wd course two years ago and only one dampener was used but I can see the logic in two and the positioning. :cheers:
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Watching a video from RV Daily about snatch straps as I'm reading this. Maybe more people should watch more.
i helped make this video below for The Fraser Island Fishing Comp many years ago, it shows how simple prep work and going slow still unbogs a well stuck fourby (I didn't mean to bury my vehicle that much...lol). What you don't see in the video is the recovery vehicle actually stalled and stopped after it took up the slack of the strap, we couldn't show the Patrol (owned by the guy these days known as Dingo Dave from Offroad Adventure Show) in the video, as it was a Toyota sponsored event. Speed has nothing to do with making a snatch strap work properly, it just adds danger to the situation.
https://m.youtube.com/watch?v=oISdDPliZSA
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At least you didn't have to play with the shovels Mal.
Great looking spotties... ;D
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At least you didn't have to play with the shovels Mal.
Great looking spotties... ;D
i didn't sell them to you, saying they've never been offroad did I?...lol
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Thanks Charlie Brown, did our 4wd course two years ago and only one dampener was used but I can see the logic in two and the positioning. :cheers:
Mate, it is a great credit to you that you did a 4WD course. Well done. Most people, read macho males, buy a fourbie, think they know it all, never read instructions or take advice and go off and “learn from their mistakes”. Sometimes those mistakes are fatal.
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A snatch strap by itself going through a laminated window and keep enough momentum to kill someone.
Really?
I can't help but think something shaped like a letter "D" was on the end of that as well......
What a sad incident for everyone.
It can happen, although this example is not directly comparable -
A company on the other side of Vic that we share notes with was trying to tow one of their bogged tractors out with another tractor using a very heavy snatch strap. This was their normal recovery process. The eye of the snatch strap broke at the towing tractor end, recoiled back towards the stuck tractor, nicking the top of the radiator and intercooler as it passed through the front top edge of the bonnet, then passed through the front windscreen, somehow missed the driver and lodged in the rear windscreen.
Again, not directly comparable due to a lot heavier strap, but only marginally heavier glass.
We had already moved from snatch recovery to building a purpose built recovery vehicle using 60,000lb winch and snatch block on every recovery. Previously (and before I joined the company) their most difficult recovery involved a 4 tractors all hooked to one bogged tractor. Scary just thinking about it. All snatch straps have now been destroyed to make sure no one uses them "just one last time".
The other company now also has a purpose built winch truck.
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Use gear in the manner that's been designed for.
as a mate of mine said "if you push it to the limit, don't be surprised when you get there"
regardless if it's a snatch strap shovel or winch!
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Always sad reading stories like this. May have been avoidable, perhaps just one of those unfortunate events where everyone did everything right and things still went horribly wrong... we won’t know if we weren’t there.
Regardless, it’s a sobering reminder to make sure we do recoveries as safely as possible. There’s a lot of inherent risk regardless of how they’re attempted, keeping it minimal is always a good idea.
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The recommended safe method is two (2) dampeners. One at each end, a metre from each attachment point.
People put far too much emphasis on dampers. On wire rope they make sense, but not on dyneema and certainly not on snatch straps.
Think about how much energy is in a strap when it breaks, what do you think that pissy little bit of canvas is going to do for you?
https://www.youtube.com/watch?v=M0-p_o91f7Y (https://www.youtube.com/watch?v=M0-p_o91f7Y)
https://www.youtube.com/watch?v=-3avKbgSfuA (https://www.youtube.com/watch?v=-3avKbgSfuA)
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People put far too much emphasis on dampers. On wire rope they make sense, but not on dyneema and certainly not on snatch straps.
Think about how much energy is in a strap when it breaks, what do you think that pissy little bit of canvas is going to do for you?
https://www.youtube.com/watch?v=M0-p_o91f7Y (https://www.youtube.com/watch?v=M0-p_o91f7Y)
https://www.youtube.com/watch?
v=-3avKbgSfuA (https://www.youtube.com/watch?v=-3avKbgSfuA)
And if it's not the strap that breaks and it's the shackle, recovery hook or God forbid towball you have a metal projectile travelling at speed. Sorry but I will stick with using a damper.
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People put far too much emphasis on dampers. On wire rope they make sense, but not on dyneema and certainly not on snatch straps.
Think about how much energy is in a strap when it breaks, what do you think that pissy little bit of canvas is going to do for you?
Dampers definitely DO work on snatch straps. They help to direct the broken strap down towards the ground, which stops them from going through windows. They also provide air resistance which decelerates the broken strap and/or anything attached to the end of it (if it has broken the mounting point for example).
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The recommended safe method is two (2) dampeners. One at each end, a metre from each attachment point.
But if the strap then breaks anywhere in the middle (not as common but certainly not unheard of) then your dampeners will virtually be redundant.
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Having a damper with a little bit of weight to it may at least help in majority of circumstances, and is less likely to cause harm. The potential benefit of using one is enough that I'll keep doing it. I do see your point, Symon. There's a heck of a lot of energy in snatch straps under load (really don't feel like doing the calculations on that when my physics is so rusty! ;D ) but on the off chance a damper could save my life or that of someone else around me, I'll keep using them.
That said, using a damper means next to nothing when you go and attach your giant elastic band to some weak metal projectile-to-be like an unrated shackle or towball...
No recovery is completely safe and routine, and shouldn't be treated like it is.
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But if the strap then breaks anywhere in the middle (not as common but certainly not unheard of) then your dampeners will virtually be redundant.
Sorry Tryagain, you got a little excited and didn't correct it before posting. Or at least, I hope that's the case.
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Sorry Tryagain, you got a little excited and didn't correct it before posting. Or at least, I hope that's the case.
Thanks fixed. That's what can happen when you don't read what you have written before you hit post.
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People put far too much emphasis on dampers. On wire rope they make sense, but not on dyneema and certainly not on snatch straps.
Think about how much energy is in a strap when it breaks, what do you think that pissy little bit of canvas is going to do for you?
https://www.youtube.com/watch?v=M0-p_o91f7Y (https://www.youtube.com/watch?v=M0-p_o91f7Y)
https://www.youtube.com/watch?v=-3avKbgSfuA (https://www.youtube.com/watch?v=-3avKbgSfuA)
Back in to 90's when the Brisbane 4wd show used to held in the park opposite the RBH (getting old :'( ), One 4wd club had a display setup showing exactly how a dampener works on a snatch. They would tension a strap with a winch - through a car bonnet with a hole in the middle (through which the strap went), and firstly let fly with a 2t shackle on the end which would punch straight through the bonnet and leave a mess. Next they did it with a dampener 1/3 in from the shackle end. It worked very well - the dampener 'caught' the snatch strap as the shackle flew past and the whole show would literally drop out of the air every time. The dampener never moved more than about a metre - Air brake is the correct term. You don't need any extra weight in the dampener. As you can imagine I don't think any show organisers these days would get the insurance to put on such a display, but it was certainly a great drawcard. I'll never forget the sound and the damage that shackle caused. You could hear it all over the showground when they let it go.
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People put far too much emphasis on dampers. On wire rope they make sense, but not on dyneema and certainly not on snatch straps.
Think about how much energy is in a strap when it breaks, what do you think that pissy little bit of canvas is going to do for you?
http://www.whyalla4wd.org.au/Shackles.html (http://www.whyalla4wd.org.au/Shackles.html)
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
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Dampers definitely DO work on snatch straps. They help to direct the broken strap down towards the ground, which stops them from going through windows. They also provide air resistance which decelerates the broken strap and/or anything attached to the end of it (if it has broken the mounting point for example).
I think the question though is how much difference they make, if the strap is breaking then there is normally a LOT of force involved, that in proportion to the wind resistance and weight involved in a Dampener would somewhat dwarf it.
Back in to 90's when the Brisbane 4wd show used to held in the park opposite the RBH (getting old :'( ), One 4wd club had a display setup showing exactly how a dampener works on a snatch. They would tension a strap with a winch - through a car bonnet with a hole in the middle (through which the strap went), and firstly let fly with a 2t shackle on the end which would punch straight through the bonnet and leave a mess. Next they did it with a dampener 1/3 in from the shackle end. It worked very well - the dampener 'caught' the snatch strap as the shackle flew past and the whole show would literally drop out of the air every time. The dampener never moved more than about a metre - Air brake is the correct term. You don't need any extra weight in the dampener. As you can imagine I don't think any show organisers these days would get the insurance to put on such a display, but it was certainly a great drawcard. I'll never forget the sound and the damage that shackle caused. You could hear it all over the showground when they let it go.
It would be interesting to know what percentage of a straps rating they were letting it go at, It would likely be able to punch a hole through a bonnet at a fraction of the force involved when compared to a good straps breaking strain and therefore be much easier to arrest a lesser force with a dampener than it would with the full force involved, from your description the shackle was also actually hitting the dampener which would be reasonably effective but not sure how realistic it would be in the real world with vehicles often at different elevations in a recovery.
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I think the simple question is, "would you let your wife or child stand in the vicinity when using a snatch strap" I would think not, as it is inherently unsafe to do so.
So in the name of safety, you would use only rated recovery points, dampers and proper procedures to keep everyone safe including yourself.
Those who don't put themselves and others at risk of serious injury or death.
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Did anyone actually look at the videos I posted before commenting?
Sure a damper may do something, but not enough in my opinion. Especially if you have a bit of metal flying back at you.
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Did anyone actually look at the videos I posted before commenting?
Sure a damper may do something, but not enough in my opinion. Especially if you have a bit of metal flying back at you.
Looking at some dampers, I cant see how they work.. they velcro shut... I've never seen one go off in real life in anger, and dont want to.. I usually go a long way back from teh recovery unless Im either recovering or being recovered.. watch from a long distance.. shackles are ****in heavy, and at 350kph, theres no second chance.
PS... the tractor was going nowhere ;)
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Did anyone actually look at the videos I posted before commenting?
Sure a damper may do something, but not enough in my opinion. Especially if you have a bit of metal flying back at you.
Your first video they were not using traditional dampers wrapped around the rope so they would not be as effective
The second video there is a marked difference in deceleration on the last example to my eyes, a great demo of how not to use one in the second example
I always use one, the delta you describe as "something" may just be enough to save a life, I'll take it every time.
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Only seen one snatch strap let go. Was at the first crossing of the Old Telegraph Track. The day before Hero was there with his big mud tyres, his diff lockers and his attitude and ripped the Shite out of the track by crossing over and over. Next day a guy bogged at the bottom. Out came a snatch strap. It didn't look fit for purpose to me and I thought maybe better a winch strap and help pull him out. Well first attempt the car didn't budge and with no dampener the strap let go in the middle. No one was hurt which was the main thing. I watched maybe another 10 cars being pulled out with the extension strap. Thing is a snatch strap is not always the way to go. Whatever you use should be in good condition and rated to its use. And have a think of how it can be done in a safe way. A big problem is people don't know or don't think when using gear like this.
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But if the strap then breaks anywhere in the middle (not as common but certainly not unheard of) then your dampeners will virtually be redundant.
The recommendation to use two dampeners, one at each end, is to slow down the attachment point and/or shackle, not necessarily the strap. I acknowledge that a broken strap on its own can cause an injury simply because of the force and speeds involved. Certainly would injure a bystander. But a busted strap, broken in the middle, that is just a strap on its own which is reduced in length, and has no weight at the end, not even a loop to add weight, is very unlikely to come rocking through a windscreen or rear window. The strap is wide and flat and fairly light, not heavy and with its mass spread along its length. Its mass is not concentrated like a busted attachment point or shackle. Anyway that is my opinion.
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The recommendation to use two dampeners, one at each end, is to slow down the attachment point and/or shackle, not necessarily the strap. I acknowledge that a broken strap on its own can cause an injury simply because of the force and speeds involved. Certainly would injure a bystander. But a busted strap, broken in the middle, that is just a strap on its own which is reduced in length, and has no weight at the end, not even a loop to add weight, is very unlikely to come rocking through a windscreen or rear window. The strap is wide and flat and fairly light, not heavy and with its mass spread along its length. Its mass is not concentrated like a busted attachment point or shackle. Anyway that is my opinion.
That makes a bit more sense, although if someone is safety conscious enough to be using two dampeners, then chances are they are using rated shackles and attachment points so the probability of those giving way before the strap would be extremely low, if for some reason you decided to pull someone out though and they didn't have a rated attachment point, then putting one on their end would make sense (although offering to help may not) .
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Your first video they were not using traditional dampers wrapped around the rope so they would not be as effective
In one test it was a 4.5kg sandbag, which got thrown up and hit the tractor window. You are saying that is less effective than a flap of canvas?
I have broken dozens of straps, and the main reason for that is I only use the smaller 8t straps instead of the 15t or higher ones which in my opinion should never be needed in a 4WD recovery. You want the strap to be the weakest link, I'm totally comfortable with a strap breaking as long as the recovery points and the shackles stay intact.
As shown in the videos, tag lines are far more effective than dampers. Those in this thread puffing up their chests about safety should be pushing those instead of flaps of canvas that have dubious effectiveness.
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I think if you really wanted the safest way, what would work better than the fold over the top dampener is a decent rope used as a tether, attached independently to the shackle/tie down point at each end, and tied/attached at 1/3 and 2/3 of the way along the strap with about 30% slack allowed (to allow for the about 25% stretch) between the ends and where it is tied on as well as the two tied/attached points, It should work to arrest any break, wherever it may occur.
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I think if you really wanted the safest way, what would work better than the fold over the top dampener is a decent rope used as a tether, attached independently to the shackle/tie down point at each end, and tied/attached at 1/3 and 2/3 of the way along the strap with about 30% slack allowed (to allow for the about 25% stretch) between the ends and where it is tied on as well as the two tied/attached points, It should work to arrest any break, wherever it may occur.
or use purpose made equipment ...
http://www.comsew.com.au/products/snatch-straps/ (http://www.comsew.com.au/products/snatch-straps/)
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https://youtu.be/oD2zci3qfgE
This is closer to my experience. It is winch cable rather than a snatch strap, but you can see how they work. Before dampeners we were taught to use a towel tied around it. The test uses a fail point on the car. You are looking for how the cable shoots back at the tree. A simple flap at 1/3 from the recovered vehicle. As stated prior, this mimics what I was watching with the snatch strap and shackle at the display.
I suppose the main thing is something is always better than nothing, and putting something half way along achieves nothing much.
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Shackle Vs gumtree ...
https://www.youtube.com/watch?v=sxQy1E4CCWs (https://www.youtube.com/watch?v=sxQy1E4CCWs)
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People put far too much emphasis on dampers. On wire rope they make sense, but not on dyneema and certainly not on snatch straps.
About eight years ago I found something on the net from that I think from memory was from the SA 4wd Association. They said they had deleted instructions on using dampers from their training manuals because their testing had shown they don't work. The testing in the first link that you posted showed what a strap could do with a 10 lb bag of sand. Who knows where it would have gone had one been on each end.
The first thing I thought of when I saw that video was where is the protection for the tractor driver? He certainly needed it in the last scene. It may not have been a happy ending if the strap had a shackle on the end of it. Many people inside cars have been killed with these straps.
I would like to see those tests done again with the usual car type recovery points on the back of the dozer and tractor and shackles on the strap. It could be done with and without dampers. You would need steel plates covering the back of both vehicles first
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People put far too much emphasis on dampers. On wire rope they make sense, but not on dyneema and certainly not on snatch straps.
Think about how much energy is in a strap when it breaks, what do you think that pissy little bit of canvas is going to do for you?
We had a rope break whilst winching cables at work once and though it was thicker than dyneema I was very impressed by the indentation left in the steel sheet that covered the brick wall where it hit.. As for using a damper I would rather have one or two on there than none at all. It might not stop a flying shackle but it might slow a rope down and doing less damage.
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We had a rope break whilst winching cables at work once and though it was thicker than dyneema I was very impressed by the indentation left in the steel sheet that covered the brick wall where it hit.. As for using a damper I would rather have one or two on there than none at all. It might not stop a flying shackle but it might slow a rope down and doing less damage.
If you are talking about wire rope I fully agree with you. Having dampers on wire rope makes sense, it doesn't on dyneema as synthetic rope doesn't store anywhere near as much energy and whilst it may recoil it certainly is not as dangerous. My argument is that there is much more energy in a snatch strap, so much so that the typical dampers that people use are near useless.
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We were using synthetic rope . A damper wouldn't have helped much in our situation but for a synthetic rope to make an indentation like it did was hard to believe. I think the damper is not to stop the rope from flying through the air but to drag it down to the ground to help slow it down and if it helps even a little bit why not just put it on in case.
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typical dampers that people use are near useless.
Are you basing this on opinion or science?
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Did anyone actually look at the videos I posted before commenting?
Sure a damper may do something, but not enough in my opinion. Especially if you have a bit of metal flying back at you.
From some of the replys I was thinking the same thing. If a strap on its own can shift a sand bag that easily, what chance does a damper have of remotely slowing a shackle down enough? I think a secondary tether to the shakle secured to a seperate point on the vehicle would be far more effective at not only slowing the shakle, but would have more of a chance of actually arresting a flying piece of metal before it hits the other vehicle - isnt that a more sensible option compared to just trying to slow it down?