Page 10 - Cliff Jacobson - Outdoor Knots

Memory. The ability of a rope to retain a coiled or knotted shape is called
“memory.” Lariats and throwing lines must necessarily “remember” their
manners or they’ll snag when played out. Generally, stiffness and good memory
go hand in hand—but not always. For example, polyethylene line is very
flexible, but it never forgets its store-bought windings. Most high-memory ropes

don’t take knots very well.
Ultraviolet degradation. This is important to consider if your ropes are
exposed to sunlight for long periods of time. Table 2 on the next two pages
provides the comparative specifics.
Stretch. Towing and mountaineering work demand a stretchy rope; “tie-
down” applications require the opposite. Natural-fiber ropes (such as manila,
hemp, and sisal) shrink when wet, while nylon ones stretch under load. Forty
years ago, campers faithfully loosened natural fiber tent guylines each night
before they retired. Today’s campers tighten nylon ropes when the sun goes
down and several times during a storm.
Floatability. Polypropylene and polyethylene (which float) are the logical
choices for water-ski ropes and throwing lines.
Effects of chemicals. Spill insect repellent on polypropylene rope and you’ll