MaineSail, why are the requirements for a pendant anything like a rode?
They are similar but don't have the same needs. A mooring pendant goes over the chock in the same place for months or years on end while an anchor rode may only ever sit on the chock in that location a few times over its life. In this regard chafe protection is one of the most important aspects of a mooring pendant. It must also be stretchy and have a tight angled braid which allows for this stretch. Most moorings are all chain at a 2:1-3:1 scope ratio and the pendants 12-20 feet long, though most should be longer. You are dependent upon the stretch in that 12 - 20 feet of line to prevent shock loading of your deck, cleats and chocks. So pendants need to be highly abrasion resistant, stretchy, resistant to UV, a double braid helps protect the inner core in this regard, and strong.
For anchoring the idea that you "must" use three strand in a rope rode, due to its stretch, is somewhat misleading as their are now a number of options such as Brait, mega plait and Nova Gold as well as some others that equal or have greater stretch characteristics and also flake better and don't hockle or unlay.. I personally feel that the stretch characteristics of many "anchor specific" rodes is a little too much when used in an all rope situation so finding the right combination of rope to chain was the best middle ground for us..
Folks have anchored successfully using all chain and a 15 +/- foot snubbers for years & years on end. No matter how stretchy your snubber is 6-10% of 15 feet is not a hell of a lot of stretch. NER 5/8" three strand stretches about 6% at 10% of tensile strength. 6% of 12,200 is over 1200 pounds of holding power. That is damn near hurricane strength and the chain would be drawn near bar tight and the snubber would stretch less than a foot. So is all that stretch absolutely necessary, when anchoring with basically no stretch, has been done for years and years and years by boaters who use all chain and relatively short snubbers? In storm conditions, where you really need your system to perform, any caternary is effectively diminished to a point of no impact on the system, in both chain and rope rodes.
Contrast that to the guy who has 200 feet of three strand rope rode in that same hurricane. His rode at 6% stretch would be stretching about 12 feet! Both situations work but one guy has less than a foot of stretch and one guy has 12 feet. I would suspect that the guy with 12 feet of stretch would have some rebound and would wind up sideways to the wind more so than the guy with less stretch.
As has been noted not all three strands are created equal and some of them a pure junk so you need to be careful. Double braids are the same and also have lots of quality variables. The big guys like Yale, Samson, NER and Nova are all reputable.
As for mooring pendants the outer jacket on a double braided line is mostly superficial and can serve to protect the inner core of the line from both UV and abrasion which is where the strength is. Good mooring pendants are not a nylon cover over a nylon core they are a polyester jacket over a nylon core. Don't expect to find this polyester/nylon double braid at your local chandlery on a roll. Don't trust your local mooring installer to buy and install the appropriate double braid for the job. If you want the right pendants ask for Yale Polydyne by name. These are made only by Yale and each pendant has a serial number. They take this stuff very seriously. Many installers will buy what ever they can get the cheapest and will ignore stretch and construction characteristics.
Polyester is significantly more abrasion resistant than nylon and MIT specifically studied this a number of years ago as related to mooring pendants. Three strand has no protective outer jacket, no polyester jacket and relies on the user to install chafe gear which is often of the incorrect type. Due to this any chock abrasion is directly impacting the strength of the rope where a double braid can have some jacket wear and still be at or near full rated strength.
The biggest problem with pendants is heat. Nylon begins to lose considerable strength above about 300F. For this reason chafe gear that breathes and is NOT water proof is better suited than leather, fire hose or rubber tubing. I have seen a number of solid hard spots in nylon pendants after storms. These hard spots are brittle and lead to failure far faster. With a three strand line this is harder to detect as the entire line is rather hard and stiff after use or after a storm. A good double braid can be kneaded between your fingers along it's length, especially where it went over the chocks, and inspected for hard lumps or hard spots and retired if necessary. Because of the nature of the braid inside a double braided line identifying hard spots is much easier. I do this after every storm and it takes about 5 minutes.
This was a hard spot I detected after a Nor' Easter her in Falmouth, ME.
I needed to really poke at it to tell as it is very tough to see visually. That entire lay is toast yet I can almost guarantee the owner would have never identified it so I left a note and marked it with a Sharpie marker...
When these lumps occur in the middle of the line it is all but impossible to tell.
My findings after studying mooring failures for a good part of my adult life.
#1 - 2 pendants of un-equal length
#2 - Chafe protection should be woven type
#3 - The longer the better. A steep angle off the chock leads to increased wear and heat.
#4 - Use a swivel
#5 - REMOVE YOUR ANCHOR IN A STORM
I actually got to capture this mooring pendant failure ON FILM!!!
Both Pendants Still Intact:
And DOWN:
And up & SNAP!
Easier to see the snapped pendant in this shot:
