An incident worth talking about. Kinetic Recovery Accident.
- Thread starter Metcalf
- Start date
Metcalf
Expedition Leader
Good (bad) stuff for everyone in the sport to see. I think it's important to see these incidents and I thank you for sharing it in detail with the community. My takeaways from the long format video.....
The soft shackle break was more typical than thought. In testing, pretty much every soft shackle will fail in the noose 'similar' to this but I did notice a few things that are worth mentioning. 1.There is a bit more 'tail' past the noose which is a bit of an anomaly. This could be a situation where one of the legs was cut and caused the noose to come undone and pull through itself. 2. There was a lot of compacting of the fibers under the top knot, and I can't tell if the soft shackle 'tails' where turned back and buried in the legs. There is a measurable increase in strength on units where the noose is going around 4 diameters of rope vs only 2 diameters of rope. 3. I don't like soft shackles with single buried legs. I notice they have a tendency not evenly load both legs if everything isn't been milked into place. This can lead to a situation where one leg is taking most of the load. You also can't easily inspect the 'inner' leg for wear and the 'outer' leg takes most of the abuse.
I like using soft shackles, and continue to build my vehicles to directly support them, but if you have a hard shackle tab style mount, just use a hard shackle. This means no keeping the hard shackles on the mount full time so they can't be opened by hand or keeping a tool handy to be able to undo them if they are kept tight. ( note: if you keep them on the bumper full time, eventually they will corrode shut if they don't get used regularly ). Just try to eliminate as many 'extra' connection points as you can even if it is slightly less convenient.
Rope size and Impulse loading. Honestly, while the speed of the towing vehicle was definitely above what manufacturers would recommend for a safe kinetic recovery ( 5mph ), it didn't look crazy fast. I tried to do some estimating of the speed from the drone video and how far/fast the vehicle was moving. I came up with something about 10-12mph? Anyone else try anything similar? I think it's worth the time to fire up a GPS or digital speedo on your vehicle and just pace off what 5mph feels like ( only a fast walk! ) vs say 10mph ( a decent run? ) just to remind yourself how easy it can be to have a vehicle going that fast during a recovery if you're getting sporty with it.
I do think the 1" rope was going to make everything feel much stiffer, but there is going to be a balance there for overall strength vs the 'feel' of the rope. I agree that at 7/8 rope would feel 'better', but it will narrow up the safety margin a bit also. I do think having the rope fail is better than having an anchor fail. It would be interesting to do some testing on rope size vs what the load was on the anchor with the same vehicle speed. I think the softer 'impulse' of the smaller ropes will have a noticeably less peak load on the anchor even with the same input energy.
Overall, this is a good reminder that we should probably be looking at using BOTH recovery points whenever possible when doing a kinetic recovery. I'd also lean towards using an independent leg bridle system vs an equalizing bridle. Most kinetic recoveries are going to be in a relatively straight line ahead of the vehicle, and I am more interested in making the bridle system redundant vs trying to spread the load out perfectly evenly over multiple recovery points. In this case, it would have been nice to have the 2nd leg of an independent bridle be able to help 'catch' things when one of the attachment points failed. Note: Using a bridle does not 'half' the load on the anchors generally speaking. Even with a longer bridle there is going to be an additive inward side load on the recovery point. The shorter the bridle, the worse it gets.
Enough for now.
The soft shackle break was more typical than thought. In testing, pretty much every soft shackle will fail in the noose 'similar' to this but I did notice a few things that are worth mentioning. 1.There is a bit more 'tail' past the noose which is a bit of an anomaly. This could be a situation where one of the legs was cut and caused the noose to come undone and pull through itself. 2. There was a lot of compacting of the fibers under the top knot, and I can't tell if the soft shackle 'tails' where turned back and buried in the legs. There is a measurable increase in strength on units where the noose is going around 4 diameters of rope vs only 2 diameters of rope. 3. I don't like soft shackles with single buried legs. I notice they have a tendency not evenly load both legs if everything isn't been milked into place. This can lead to a situation where one leg is taking most of the load. You also can't easily inspect the 'inner' leg for wear and the 'outer' leg takes most of the abuse.
I like using soft shackles, and continue to build my vehicles to directly support them, but if you have a hard shackle tab style mount, just use a hard shackle. This means no keeping the hard shackles on the mount full time so they can't be opened by hand or keeping a tool handy to be able to undo them if they are kept tight. ( note: if you keep them on the bumper full time, eventually they will corrode shut if they don't get used regularly ). Just try to eliminate as many 'extra' connection points as you can even if it is slightly less convenient.
Rope size and Impulse loading. Honestly, while the speed of the towing vehicle was definitely above what manufacturers would recommend for a safe kinetic recovery ( 5mph ), it didn't look crazy fast. I tried to do some estimating of the speed from the drone video and how far/fast the vehicle was moving. I came up with something about 10-12mph? Anyone else try anything similar? I think it's worth the time to fire up a GPS or digital speedo on your vehicle and just pace off what 5mph feels like ( only a fast walk! ) vs say 10mph ( a decent run? ) just to remind yourself how easy it can be to have a vehicle going that fast during a recovery if you're getting sporty with it.
I do think the 1" rope was going to make everything feel much stiffer, but there is going to be a balance there for overall strength vs the 'feel' of the rope. I agree that at 7/8 rope would feel 'better', but it will narrow up the safety margin a bit also. I do think having the rope fail is better than having an anchor fail. It would be interesting to do some testing on rope size vs what the load was on the anchor with the same vehicle speed. I think the softer 'impulse' of the smaller ropes will have a noticeably less peak load on the anchor even with the same input energy.
Overall, this is a good reminder that we should probably be looking at using BOTH recovery points whenever possible when doing a kinetic recovery. I'd also lean towards using an independent leg bridle system vs an equalizing bridle. Most kinetic recoveries are going to be in a relatively straight line ahead of the vehicle, and I am more interested in making the bridle system redundant vs trying to spread the load out perfectly evenly over multiple recovery points. In this case, it would have been nice to have the 2nd leg of an independent bridle be able to help 'catch' things when one of the attachment points failed. Note: Using a bridle does not 'half' the load on the anchors generally speaking. Even with a longer bridle there is going to be an additive inward side load on the recovery point. The shorter the bridle, the worse it gets.
Enough for now.
Metcalf
Expedition Leader
Correct, there is a much more narrow window of operation than most people think.
On the flip side, most people can't really correctly judge speeds this low when on the fly, especially when the vehicle is slipping and sliding on the road surface. I try to remember not to exceed a fast walking pace as a rough guideline.
calicamper
Expedition Leader
I realize that using braided high tech stretch line is still relatively new to the 4x4 world.
Us sailors have been working with it for decades. Most applications on the boat we specifically seek out non stretch lines used in sail trim and halyards given stretch basically zaps power out of the sails those loads are high but we run a large safety factor in the load ratings. For example we ran 30,000 lb rated halyards on a 12,000 lb boat. Keep in mind the halyard loading is determined by sail size etc. Winch lines use the same line technology and similar hardware straight from the sailing world.
On the flip side…. Dock lines especially for heavy craft are actually designed to stretch this is the tech if you want to call it that… These kinetic ropes are right from the heavy craft dock line world.
Having seen both non stretch stuff under high load fail and the stretch line fail under load. Most sailors even newbs usually won’t ever be seen in a location were they are exposed to a line failure whip. I think a big part of that is much of the early lighter loads are literally man handled by the sailor and they literally have hands on feel for just how much load the lines are under when they really load up.
Winching and kinetic pulls its all mechanical and easy to not realize just how massive the loads could be on the lines.
That guy is really lucky to be alive. Definitely agree his video is super important and glad he shared it.
Us sailors have been working with it for decades. Most applications on the boat we specifically seek out non stretch lines used in sail trim and halyards given stretch basically zaps power out of the sails those loads are high but we run a large safety factor in the load ratings. For example we ran 30,000 lb rated halyards on a 12,000 lb boat. Keep in mind the halyard loading is determined by sail size etc. Winch lines use the same line technology and similar hardware straight from the sailing world.
On the flip side…. Dock lines especially for heavy craft are actually designed to stretch this is the tech if you want to call it that… These kinetic ropes are right from the heavy craft dock line world.
Having seen both non stretch stuff under high load fail and the stretch line fail under load. Most sailors even newbs usually won’t ever be seen in a location were they are exposed to a line failure whip. I think a big part of that is much of the early lighter loads are literally man handled by the sailor and they literally have hands on feel for just how much load the lines are under when they really load up.
Winching and kinetic pulls its all mechanical and easy to not realize just how massive the loads could be on the lines.
That guy is really lucky to be alive. Definitely agree his video is super important and glad he shared it.
craig333
Expedition Leader
I'm relatively new to using soft shackles so this is great info. I've done the same thing as far as go go go. Been yanked and done the yanking many times and this is huge reminder to Slow Down. Assess the situation.
Coincidentally I just dumped out my trauma kit, tossed a bunch of stuff and replaced and upgraded a lot of items. Keeping it readily available is something I need to keep in mind.
GMRS is great for trail comms but I wouldn't count on it for emergencies. Ham radio is better but I still carry an inreach for when nothing else works.
I stopped carrying my winch weight when I went away from wire rope. I think I'll toss that back in.
Off to see some videos on proper use of a soft shackle. Sure glad I bought good ones!
Coincidentally I just dumped out my trauma kit, tossed a bunch of stuff and replaced and upgraded a lot of items. Keeping it readily available is something I need to keep in mind.
GMRS is great for trail comms but I wouldn't count on it for emergencies. Ham radio is better but I still carry an inreach for when nothing else works.
I stopped carrying my winch weight when I went away from wire rope. I think I'll toss that back in.
Off to see some videos on proper use of a soft shackle. Sure glad I bought good ones!
Tudor Tanase
Member
What I find hard to understand (leaving aside our desire to own and play with more things and the retailer's desire to sell us more gimmicks) is why we have gotten rid of tow hooks? A tow hook means NO shackles at all, which is less to fail or fly around. And less to fiddle with.
Yet another incident supporting my decision to not use kinetic ropes or straps for their intended purpose.
Anytime I’m involved with a recovery involving straps or rope I always advise to slowly take up the slack then start the pull gently, not even close to the video above.
If the obstacle refuses to give up the vehicle, out comes the winch line, much, much more controlled in my opinion.
Anytime I’m involved with a recovery involving straps or rope I always advise to slowly take up the slack then start the pull gently, not even close to the video above.
If the obstacle refuses to give up the vehicle, out comes the winch line, much, much more controlled in my opinion.
m-l_johnny
Active member
Sounds like you have no doubt seen the deck\ line safety videos we were shown in boot camp. For me that was almost 40 yrs ago, but I can still picture the sailor being interviewed about a line parting incident and him saying he got knocked down and watched his legs roll off the side of the ship.
I was on a buoy tender in the Coast Guard. One really had to keep their head on a swivel when working a buoy.
ThundahBeagle
Well-known member
Glad this is out there. I'm not an expert at this and rarely need to help someone out of a snowbank, so this is helpful...
...if you have an hour to sit there watching a video of a talking head. That could have been a lot shorter and to the point, and would help a lot more people.
Still glad it's out there
...if you have an hour to sit there watching a video of a talking head. That could have been a lot shorter and to the point, and would help a lot more people.
Still glad it's out there
Metcalf
Expedition Leader
Hooks have their own set of compromises. While they may be more convenient, they are also an 'open' system where the rope/strap can come off the hook or even become impaled on the end ( seen both over the years ). They are also not immune to becoming their own projectile if the mounting bolts where to fail.
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My take of the bumper and frame horn sustaining that much damage is the soft shackle was more than capable of doing its job.
dstefan
Well-known member
Thanks for posting this up @Metcalf , it’s a great reminder, food for a good review and discusson, and kudos to Caleb for doing an objective post-mortem. He’s a lucky guy to be alive.
I am struck that most of the comments and replies are focused around the potential for equipment failure rather than human behavior and judgement in this accident. Caleb himself pretty much puts it down to his rushing, failure to reassess the situation, using too heavy of kinetic line, and failure to advise and coordinate with the pulling vehicle’s driver. Sure, I wouldn’t buy an Amazon shackle (or other reco gear) either — too many sketchy products there, but in the end the soft shackle didn’t fail until the snatch nearly pulled out his Bronco’s recovery point and tweaked his front frame.
I’m going to go out on a limb here and say there was nothing about this accident that was equipment related and it was all human judgement related. And I certainly am not implying that I’m immune to those same errors, having made plenty myself, or am any kind of recovery expert — I’m far from it. But it seems pretty clear to me that better decisions would have made for a safe recovery with ALL the same gear and even potentially less robust reco gear, used properly for the situation.
Do we tend to overfocus on the gear stoutness and specs as a way to avoid having to hold ourselves accountable for the decisions and judgments we make out there?
I am struck that most of the comments and replies are focused around the potential for equipment failure rather than human behavior and judgement in this accident. Caleb himself pretty much puts it down to his rushing, failure to reassess the situation, using too heavy of kinetic line, and failure to advise and coordinate with the pulling vehicle’s driver. Sure, I wouldn’t buy an Amazon shackle (or other reco gear) either — too many sketchy products there, but in the end the soft shackle didn’t fail until the snatch nearly pulled out his Bronco’s recovery point and tweaked his front frame.
I’m going to go out on a limb here and say there was nothing about this accident that was equipment related and it was all human judgement related. And I certainly am not implying that I’m immune to those same errors, having made plenty myself, or am any kind of recovery expert — I’m far from it. But it seems pretty clear to me that better decisions would have made for a safe recovery with ALL the same gear and even potentially less robust reco gear, used properly for the situation.
Do we tend to overfocus on the gear stoutness and specs as a way to avoid having to hold ourselves accountable for the decisions and judgments we make out there?