A Bit About Rope

Nylon
Nylon is the strongest of all ropes in common use and, when stretched has a "memory" for returning to its original length. For this reason, it is best for absorbing shock loads, as is the case when lifting or towing. Nylon lasts 4-5 times longer than natural fibers because it has good abrasion resistance and is not damaged by oil or most chemicals. Like manila, nylon has good resistance to ultraviolet deterioration from sunlight (referred to as "U.V. stability").

Polyester
Polyester is very close to nylon in strength when a steady force is applied. Polyester, however, stretches very little (unlike nylon) and can therefore not absorb shock loads as well as nylon. It is equally resistant to moisture and chemicals and is superior to nylon in abrasion resistance and resistance to sunlight. Polyester is the most popular general purpose rope in the boating industry.

Polypropylene (Poly)
Because of its light weight, polypropylene is the only rope which floats and; for this reason, is very popular for use as pool markers and water sports. Poly is affected by sunlight deterioration (more so than any other synthetic or natural fiber rope), but its life can be extended by storing it away from direct sunlight. Poly begins to weaken and melt at 150°F, the lowest melting point of all synthetic ropes. It is not as strong as nylon or polyester, but 2-3 times stronger than manila. Because poly is less expensive than other fibers, it is the most popular all-purpose rope for the average consumer.

Manila
A hard natural fiber, manila is especially resistant to sunlight. It is very popular for public utility construction and repair because it will not melt on contact with hot wires or equipment like synthetics do. (It will burn, however, if the temperature is very high or if the rope is in contact with the wires/equipment for an extended period of time). Manila holds knots firmly and stretches very little. It must be stored dry to avoid mildew. Chemicals will cause it to deteriorate.

Sisal
Sisal, like manila, is a hard natural fiber, but its strength is about 20% less. It, too, has excellent resistance to sunlight, little stretch, and good knot-holding ability. Sisal must be stored dry to avoid mildew and chemicals will cause it to deteriorate. Common uses include gardening, bundling, shipping, and tie downs where strength is not a critical requirement.

Twisted vs. Braided Construction
There are two general categories of rope construction: twisted and braided. Twisted rope is formed by coiling three strands together in the same direction. The fibers within each of the three strands must twist in the opposite direction as the strands in order to produce a balanced rope (one which hangs straight and resists kinking). Twisted rope must be fused and taped on each end to prevent unraveling. Three general categories of braided construction exist: diamond braid with a core, diamond braid without a core (called hollow braid) and solid braid. Diamond braid is manufactured by weaving ends of yarn over and under, the same fashion in which the maypole dance is done. If there is a core around which the rope is braided, it cannot be spliced. If no core exists, the rope is called "hollow braid". The outstanding feature of hollow braided rope is the ability to splice it in seconds. Lehigh encloses a splicing fid with instructions in every bag of hollow braid poly. Solid braid is very firm, round and tightly woven with a special lock-stitch construction which prevents unraveling when cut or torn. Solid braided rope stands up especially well to chafing of blocks and pulleys. This construction cannot be spliced. When the rope as well as the core are braided, the construction is know as "braid on braid" or "double braid". This is the strongest and most expensive of all rope.