Life of 3 Strand Nylon Rode

[kmacdonald]

How long should 3 strand nylon rode last? Does it weaken with age, use?

[Alan Mighty]

Originally Posted by kmacdonald

How long should 3 strand nylon rode last? Does it weaken with age, use?

The advantages of nylon used for anchor cable include:

* it sinks in water, so slack cable does not get picked up by a passing propeller;
* nylon has considerable elasticity (hence its use as a snubbing line for an all-chain anchoring system).

Disadvantages include:

* nylon weakens when wet - it loses strength;
* rust (iron oxide) and salt get amongst the nylon fibres causing internal abrasion and weakening the cordage;
* external abrasion cuts fibres, weakening the cordage (so a nylon anchor cable needs a chain or wire pendant to keep it free from rubbing against the ground);
* nylon work hardens, losing its elasticity.

TL;DR: nylon ages with use, becoming weaker. It's not time by itself that affects nylon, it is time-in-use and contact with rust, salt, and any abrading surface.

[mrcarson]

When YOU start feeling uncomfortable with any part of your anchoring/rigging items. Change them.
Only YOU know how meticulous/suicidal you are. Keep out of sun. Wash with fresh water regularly. Lay out ALl on wharfside regularly and check. S/S wire in shackle pins.
KEEP ALL ROPES DRY. Hanging or Coiled not dumped in a heap in chain locker. AND FRESH WATER WASHED. They'll last 10 times longer

[GordMay]

Originally Posted by Alan Mighty

... TL;DR: nylon ages with use, becoming weaker. It's not time by itself that affects nylon, it is time-in-use and contact with rust, salt, and any abrading surface.

ALL, well said.
Cordage also weakens from shock loading.

[Tin Tin]

We had this as mooring lines on our dock for 12 years permanently in the sun. In year 13 one of them parted, not on a particularly stormy day. Fortunately all lines did not expire at the exact same time.

[Hartleyg]

Nylon is not particularly resistant to UV damage (sunlight), abrasion, internal damage from dirt or salt crystals can take a toll, and age causes a gradual deterioration in flexibility and strength. Exposure to petroleum products, solvents, cleaning and sterilizing agents will also age line prematurely.

Dock lines are generally sized to include a significant strength reserve, primarily to resist the inevitable degradation through use and exposure, but they can lose that reserve, sometimes without easily visible damage.

The biggest trick is to figure out when they need replacing - BEFORE an actual failure. I have found one way to identify a nylon line that has "work hardened" to a degree that indicates replacement should be done is to observe the line during the normal tighten-loosen cycle -- if the line has portions that do not flex, with a "joint" that IS flexing somewhere in the middle, it's time to replace. This applies no matter the construction or material - 3-strand, double braid or single braid, nylon, polyester or polypro (which one would hope wasn't being used for dockline, but some folks use it).

Visual inspection is of course the best thing - when outer fibers are breaking and "fuzzing out" for no observable reason, it's an indication of damage -- UV is the usual culprit, but line stored out of the sun with surface degradation evident is telling you something is wrong. It is a misconception that UV damage is only superficial - studies have shown that UV penetrates a long way inside line exposed to sunlight. Line that feels hard and inflexible is telling you its aged.

Hartley
S/V Atsa