Sizing Mooring Lines

[GordMay]

I would prefer to purchase rope from a vender with sufficient turn-over to guarantee “newly-manufactured” product; but I wouldn’t panic over a few months shelf life.

All manufacturers state something to the effect that “... Rope strength can be expected to decrease with age and use ...”

Ropes are ideally kept in a cool, dark, well ventilated place, loosely coiled and hung on either plastic tubes or un-treated wooden pegs or rope loops - not tightly coiled on spools.. Rope materials, in common with everything else on the face of the earth, deteriorate with the passing of time. Even if the rope remains un-used it gradually loses strength over the years. This 'ageing' process is speeded up enormously by poor storage or prolonged exposure to sunlight. There are very few signs, least of all the outward appearance of a rope, that give a reliable indication of it's properties. In fact, there is no practical method of determining precisely the safe life of a rope, dependant as this is on variations in age and usage. Nothing short of a test to destruction reveals the true condition of a rope. As a practical matter, five years is the recommended maximum age that a rope could remain in service.

On the other hand:

Excerpted from “Deterioration of Climbing Rope” ~ by Bill Mixon
http://filebox.vt.edu/users/raedward/cisdetrop.html
[i]”...A U.S. Army laboratory has recently published a report on the deterioration of nylon mountain climbing rope(1) ...
... There was no relation between the age of the rope and its strength loss ...”

BTW:
Mike’s 24 year old “dirty” rope may be fit for (some) farm use, but NOT aboard the boat. Dirt is one of the prime adversaries of rope.

[Talbot]

If you are buying enough to make purchase of a full reel a possibility, why not go direct to the manufacturer. You should also make a cost saving!

[Alan Wheeler]

The biggest enemies to ropes are, use, tension, UV, moisture and dirt. A rope will not deteriate anywhere near the same extent when on a roll in a shop compared to on the boat in use.

[markpj23]

One last question (yeah right...) I've found a source that has a spool of 3/4" DACRON double braid for about $0.60 per ft. Is Dacron suitable for dock line use or does it not stretch enough?

The line selection guides I've been able to find are designed to point you to a specific manufacturer's product...

Should I insist upon nylon line for it's ability to stretch? Or does it really matter?

[BC Mike]

My Yacht Club requires rubber snubbers or springs. This takes care of the stretch problem and you can use any line you like. The springs I use for the 28 foot boat have been in service since 1979. Rubber snubbers may not be as durable.
Michael

[GordMay]

Dacron line is NOT suitable for mooring (dock nor anchor) lines, and (yes) you should insist upon nylon line for it's elasticity.
Mooring compensators, snubbers, springs & whatever can provide additional shock absorption.