ROPE KNOWLEDGE CENTER

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Choosing a rope

WORKING LOADS
It is impossible to establish hard and fast recommendations regarding working loads due to the wide range of rope uses, rope conditions, exposure to various factors affecting rope behavior, and the degree of risk to life and property involved. The working load tabulations are based on new, unused rope in excellent condition. These are only guidelines—even when properly spliced and used in non-critical applications under normal conditions.

If potential injury to people or damage to property exists, working loads should be reduced. Never increase the working load beyond the given guidelines without expert advice regarding the conditions and risks involved. It must be determined that the rope is in excellent condition.

Working load figures are void if the rope has been subjected to dynamic loading, high temperatures, extended periods under load, extreme stress, improper storage, or improper use.

DYNAMIC LOADING
Dynamic loading occurs when rope is subjected to sudden or extreme stress, such as abrupt straining or stopping of a load. The effect of dynamic loading is greater on low-elongation ropes (such as polypropylene) than on high-elongation ropes (such as nylon). The effect is also greater on short ropes than on long ropes.


TENSILE STRENGTHS
Tensile strengths are determined from tests on new, unused rope in accordance with standard test methods of the Cordage Institute.

rope construction

HOLLOW BRAIDS
Fully spliceable and resistant to moisture and rot, hollow braid rope floats indefinitely and cannot hockle, kink, or back-lay. Common uses include water ski tows, anchor lines, pool rope, dog leashes, and applications where quick, easy splicing to hardware or other components is desirable.


TWISTED ROPE
Size for size and pound for pound, twisted rope is the strongest and least expensive rope manufactured today. It is a spliceable, general-purpose rope used widely for anchor lines, dock lines, blocks and tackle, winch ropes, tow ropes, tie-downs, and many industrial and marine applications.

When turned in the opposite direction of the rope lay, twisted rope will hockle. Hockles are detrimental to rope performance and cause permanent damage when strain is applied.

rope types

NATURAL FIBER ROPES
Although less affected by sunlight than synthetic fibers, it's important to recognize the characteristics and limitations of natural (Abaca) fiber ropes such as manila. Even under ideal storage conditions, natural fibers will decompose and lose up to 50% of their tensile strength over time. Because they are prone to mildew and dry rot, natural fiber ropes must be stored completely dry.


SYNTHETIC ROPES
Man-made fiber ropes are stronger and more durable than natural fiber ropes. They are generally unaffected by rot, mildew, or most chemicals and may be stored wet or dry. The service life of synthetic ropes exceeds that of natural fiber ropes and they have proven to be more efficient and cost-effective.


NYLON
Nylon is the strongest rope we manufacture. Its elasticity can absorb shock loads that would break ropes made of other fibers. Resistant to abrasion, rot, petroleum products, marine growth, and most chemicals, nylon rope will last many times longer than natural fiber ropes. When wet, nylon rope loses approximately 15% of its strength—an important consideration when selecting nylon rope for your application.


POLYESTER
Polyester rope has less stretch and elasticity than nylon, plus greater resistance to ultraviolet degradation from sunlight. Other characteristics of these two fibers are practically identical.


POLYPROPYLENE
Extensively used for many applications, polypropylene is a strong, lightweight, floating rope. Resistant to rot, mildew, petroleum products, and most chemicals, polypropylene is an excellent all-purpose utility rope.

ROPE USE AND CARE

OVERLOADING
Avoid sudden strain. When a working load has been used to select a rope, the load must be handled slowly and smoothly to minimize dynamic effects and avoid exceeding the safety provisions built into the rating.


ABRASION
All rope will be severely damaged if subjected to rough surfaces or sharp edges. Chocks, winches, drums, and other surfaces must be kept in good condition and free of burrs and rust. Pulleys must be free to rotate and should be the proper size to avoid excessive wear. Keep rope clean—dirt and grit act as abrasives and will damage the rope fibers.


RECOIL
Never stand in line with rope under tension. Should the rope fail, it will recoil with considerable force, potentially causing serious injury to persons or property anywhere in the vicinity. This danger can exist even from failure of fittings within the rope's safe working load. Always check all fittings, bolts, shackles, splices, and connections before using.


HEAT
Synthetic ropes can lose up to 50% of their strength when used or stored at temperatures above 140°F. Slippage or surging on a capstan or winch will cause localized overheating, resulting in severe loss of tensile strength. Consult the manufacturer for recommendations regarding rope size and type for proposed continuous heat exposure conditions.


KNOTS AND SHARP BENDS
Both knots and sharp bends can decrease rope strength by as much as 50%. Use the manufacturer's recommended splices and avoid sharp bends for maximum efficiency and safety.

CHEMICALS
Most synthetic ropes are resistant to oil, gasoline, paint, and most chemicals. Natural fiber ropes can be severely damaged by exposure to chemical fumes or direct contact. Consult the manufacturer for guidance on specific chemical exposure situations.


ROPE STORAGE
Synthetic ropes may be weakened by prolonged exposure to ultraviolet rays or extreme heat. Store them out of direct sunlight in a cool, dry, and well-ventilated place. Natural fiber ropes should be kept off the floor with ventilation underneath, as they are extremely vulnerable to mildew and decay if stored wet.

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