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
[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
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.