Synthetic rope snapback: killed one, injured four

[StuM]

Originally Posted by thinwater

Poly-what?

• Polyester
• Polyamide
• Aromatic polyamide
• Polypropylene
• Polyethylene

The term "Poly rope" is almost universally used an abbreviation for polypropylene rope.

[RaymondR]

Originally Posted by StuM

The term "Poly rope" is almost universally used an abbreviation for polypropylene rope.

Whichever poly they make mooring lines out of. I vaguely recall we used polypropolene but I would not swear to it.

[fxykty]

I’ve spent a lot of time on the Timms Ropes site (they make Acera UHMWPE ropes among others) and in their mooring lines section they show the use of non-stretch UHMWPE ropes for the mooring lines along with short strops of stretchy rope to act as shock absorbers for large ships . They also show UHMWPE with nylon strops used in towing and winch systems as well.

The benefit of using UHMWPE is that it doesn’t store energy, floats, and is incredibly strong and light and low profile compared to wire ropes and nylon/polyester equivalents. Short sections of stretchy ropes takes care of shock absorption without adding too much stored energy to the entire system. I assume all sorts of fleets including military are switching.

[Jim Cate]

Short sections of stretchy ropes takes care of shock absorption without adding too much stored energy to the entire system.

Hmm.... sounds kinda like an all chain rode with a snubber! Who woulda thought?

Jim

[zeehag]

i watched as mooring lines made of double braid and yacht braid snapped in storms in san diego moorings... had stainless cable snap as in shroud snap in dry tortugas on opb....
dragging a ship or boat off a reef or beach is a fools errand. inertia wins.
haste makes waste.
always fun to watch, especially if one uses the lesson well.

[thinwater]

Originally Posted by StuM

The term "Poly rope" is almost universally used an abbreviation for polypropylene rope.

I know that. It's a sloppy habit I would like to see change. I cringe every time I here some say that a part is made from "poly;" either polymer, composite, metal, or some other more accurate generic term would be much better.

[thinwater]

Originally Posted by RaymondR

Whichever poly they make mooring lines out of. I vaguely recall we used polypropolene but I would not swear to it.

Depending on the country and the size of the boat, nylon (polyamide), polyester, polyethylene (in the form of Dyneema), and polypropylene are all popular. Really.

[Steve Bean]

In about 1970 I was trying to pull out an oak stump about 3 inches in diameter and six feet high, thinking it would bend over and break the roots. I was using a 3/4 inch three-strand nylon rope about 30 feet long and a small 4-wheel drive car. The tree bent down and the top 18 inches - like the big end of a baseball bat - broke off and struck the tailgate so hard that it didn't just dent it; it bent the tailgate. I could have been killed ...

[PGDO]

Originally Posted by fxykty

I’ve spent a lot of time on the Timms Ropes site (they make Acera UHMWPE ropes among others) and in their mooring lines section they show the use of non-stretch UHMWPE ropes for the mooring lines along with short strops of stretchy rope to act as shock absorbers for large ships . They also show UHMWPE with nylon strops used in towing and winch systems as well.

The benefit of using UHMWPE is that it doesn’t store energy, floats, and is incredibly strong and light and low profile compared to wire ropes and nylon/polyester equivalents. Short sections of stretchy ropes takes care of shock absorption without adding too much stored energy to the entire system. I assume all sorts of fleets including military are switching.

I have been sailing on large container vessels with these ropes for the past 20+ years. As you mention no snapback, very light, they float and are very strong.

But significant drawbacks are that they damage quite easily especially heat damage due to chafing, they are very expensive, think 10000USD for 220m D42mm and they break on a sudden force. For example, in swell or surge ports when a slack line suddenly snaps tight. So, you always need to have your winches on autotension and hawsehole rollers need to be well maintained.

[PJHoffnet]

Originally Posted by JoeRobertJr

This article is about the Korean Navy. I recall the training videos in my own US Navy days with mannequins dressed in sailor clothes being mowed down when a synthetic line parted. The visual was very effective.

The Villain in the Line Locker ... one of my favorite training films of all time.

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

As the Deck Division Officer on my first Submarine I only had one parted line and everyone was in the correct - 90 degrees off line - position and no one got hurt. Training does pay off.

[JoeRobertJr]

Thanks, PJHoffnet. That was exactly the video I remembered.

[jmorrison146]

Sounds like a shotgun round when one of them goes.