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Synthetic Winch Line Failure

(the care and feeding of synthetic rope)

 

The other incident occurred while doing a non-straight pull up a long and difficult obstacle.  The details surrounding this event were explained and discussed over some 7 forum pages.  I'll try to condense it down a bit.



This was the Rubicon just before the line failure.  We won't go into the actions of the individual on the winch rope as he already stated in the forum thread that "I honestly can't believe what I'm doing here...that's gotta be high on the list of the dumbest things I've ever done."  I don't think anyone will argue with him....it certainly is dangerous and then some.

From what I gleaned from the forum thread, the driver stopped winching at this point (to prevent the vehicle from being pulled over) and let winch line out.  Apparently slack occurred in the winch line.....and then the vehicle moved backwards down the obstacle putting a shock load on the synthetic line.  (at least that is what seems to have happened)

Should the line have failed at that point?  We don't know what the shock load was so it may have very well exceeded the working specs of the rope.


Here are the ends of the synthetic rope.  Remember, this was its first time in use .....which was when it failed.  See any similarities between this rope and that from the previous page?  It failed about 5' from the end of the rope

 

This was the anchor point for the Yellow Rubicon.  I circled a spot that was some 5' from the end of the synthetic line.  Notice that it is on rock and going over the edge of the rock.  Given the high tension on the line, and the fact that the vehicle is below grade at this point, there is good tension on the line in a downward direction.....the kind that frays and cuts the synthetic line when against a sharp object.

There is no line protection in use at this trouble spot either.  Major mistake! 

While not part of the rope failure issue, I would like to comment about using the yellow tree saver strap around the in-ground anchor (an axle shaft put down a hole in the rock).  I discussed this with Jon since he makes his own tree savers and Rocklines for his business.  If the tree saver strap is made from nylon, it will stretch about 15% ~ 30% before breaking.  This is far too much stretch for a winch point anchor.  If the tree saver strap is made from polyester, it will stretch about 3% before breaking.  While this is still 3 times more stretch than the Rockline I use, it is much safer than a nylon tree saver.  After doing some research on a couple of web sites, it appears that Warn makes their snatch straps and tree savers out of nylon (they both have the same strength rating) while ARB shows different strength ratings for their straps and lists the tree saver as polyester construction. 

Edit:  I found out today that the two people that were injured in this winching incident were standing behind the above winch point.  They both caught the backlash of the of tree saver recoiling when the line broke.  One was seriously cut and the other ended up going to the hospital for x-rays on his leg.  He's been on crutches for a week.  The hook apparently hit him and the cut was the result of being whipped with the line.   The person that was holding the synthetic line (in a previous photo) near the front of the Rubicon suffered no injuries when the line broke. 

So in summary.....if your tree saver is made from polyester, you don't need to toss it....just be aware that it will store some energy and take appropriate safety steps.  If your tree saver is made from nylon, I would be looking to replace it.  A strap made from nylon would be a bad component for anchoring the winch rope. 

 

The last thing I noticed in the thread was this last recovery photo taken after the yellow Rubicon was winched back onto it's tires.  Notice the long yellow snatch strap that is wrapped around the big rock (upper left hand corner of the photo)?  That was used, if I am not mistaken, to hold a snatch block during the recovery.  If I am correct on this fact, then that was also the absolute wrong strap to use for this action.  That strap is designed to stretch quite a bit when put under tension.  If something fails with all that stored energy in it, the results can be very bad....very, very bad.   Rockline, which has <1% stretch, would be the correct line to use for a winch or snatch block anchor like this. 

Jon sent me a couple of photos and I decided to add these to this write-up as well since they are all about line protection.  He provides two different protectors for synthetic line with one of them being the heavy duty version.
 

I use the protector shown on the left in the photo.  It can be easily slid up and down the length of the winch line.  The heavy duty protector is shown on the right.  It is quite a bit larger and does offer more protection.  If you routinely winch in situations where the rocks edges are sharp and numerous, you may want to upgrade to the heavy duty version. 


Here are the same two protectors.  You can see the difference here very clearly.  Yes, the heavy duty protector will take up more room on your winch drum....about 10' of space to be exact.  If you run 100' of 3/8" Amsteel blue, you'll only get 90' on the drum once you slide this protector over the winch line.  Winchline.com is coming out with a new protector in a few months that can be kept in the recovery bag until needed.  It will wrap onto the line for use and can then be removed and put back into the gear bag once you are done winching.  Sounds like a very good idea to me. 


I hope these last two pages have provided you with some insight as to the requirements for using synthetic winch line.  Some view these as "downfalls" of the synthetic line.  I don't.....they are simply operational requirements that must be followed when using the product.  No more nor no less than the requirements put on other components used in/on our vehicles.....using the correct fluid in your NV3550 tranny.....using the correct air pressure for your ARB air lockers.....adding the friction modifier to a clutch type LSD.....well, you get the point.

As always, if you have questions in regards to the products and components you use on your vehicles, check with the manufacturer and/or vendor for answers.  

I'll try to add more information regarding the use and care of synthetic winch rope as I get the chance. 

In the mean time, good trails and remember to TREADLightly!


 

 

 

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