Twisted Rope, Line, and Twine

It’s made in essentially the same way today as it was thousands of years ago – by twisting a bunch of fibers or yarns together to form a strand, then taking three or so of these strands and twisting them together in the opposite direction.

When long lengths of twisted rope were required for a tall mast or to hoist a load to a high place, they were formed – by hand or later with machines – in a ‘rope walk’ as long as the finished dimension, in order to avoid splices. To the same end, abandoned chicken coops are sometimes converted into rope making factories.

Natural fiber cordage for general use – mostly made from manila or cotton was the ‘state-of-the-art’ until the mid-twentieth century, when nylon rope was introduced. With it’s superior strength, rot resistance, chemical resistance and ability to absorb shock loads, nylon twisted rope was soon replacing manila and cotton in farm, industrial, and military cordage applications. Since that time, polyester and other synthetic fibers have been developed and used to produce a variety of specialty products, matching the strengths of the individual – and in some cases multiple – fibers to the needs of the work to be done.

Manila, the previously ‘state of the art’ working rope, is now – with few exceptions – recommended just for decorative use. Manila should not be used for overhead lifting or when failure could lead to damage to people or property.

As far as long term use, especially outdoors, Manila and any other natural fiber rope will eventually rot. If it is stored wet, or if it does not dry out completely after getting wet, the fibers will rot – not visibly, but on the inside – and the rope will break without warning.

Properties of 3 Strand Twisted Ropes
Size		Polypropylene		Nylon		Polyester		Composite		Manila
Diameter (inches)	Circum- ference (Inches)	New Rope Breaking Strength Lbs	Working Load Limit Range Lbs	New Rope Breaking Strength Lbs	Working Load Limit Range Lbs	New Rope Breaking Strength Lbs	Working Load Limit Range Lbs	New Rope Breaking Strength Lbs	Working Load Limit Range Lbs	New Rope Breaking Strength Lbs	Working Load Limit Range Lbs
3/16	5/8	650	54-130	880	73-176	765	63-153	–	–	–	–
1/4	3/4	1,125	94-225	1,485	124-298	1,315	110-263	1,200	100-240	540	45-61
5/16	1	1,710	143-342	2,295	192-460	2,050	171-410	1,870	156-374	900	75-95
3/8	1-1/8	2,430	203-486	3,240	270-648	2,900	242-580	2,700	225-540	1,215	101-136
1/2	1-1/2	3,780	315-756	5,670	473-1130	5,085	424-1,017	4,400	367-880	2,385	199-268
5/8	2	5,580	465-1,116	8,910	743-1,780	7,825	652-1,565	6,100	508-1,220	3,960	330-446
3/4	2-1/4	7,650	638-1,530	12,780	1,065-2556	11,200	933-2,240	8,400	700-1680	4,860	405-546
7/8	2-3/4	10,350	863-2,070	17,280	1,440-3,460	15,225	1,269-3,045	11,125	927-2,225	6,930	578-780
1	3	12,825	1,069-2,565	22,230	1,850-4,400	19,775	1,648-3,955	13,175	1,098-2,635	8,100	675-911
1-1/4	3-3/4	19,350	1,613-3,870	34,830	2,900-6,960	29,800	2,483-5,960	19,900	1,658-3,980	12,150	1,013-1,366
1-1/2	4-1/2	27,350	2,279-5,470	48,600	4,050-9,720	42,200	3,517-8,440	28,250	2,354-5,650	16,650	1,388-1,873
2	6	46,800	3,900-9,360	84,600	7,050-16,900	72,000	6,000-14,400	48,050	4,004-9,610	27,900	2,325-3,139

Working Load Limits

The Working Load is the weight or force applied to a rope in a given application.Working Load Limits (WLL) are guidelines for the maximum weight or force capacity of a given rope in general use.

Working Load Limits are calculated, using an application based Design Factor, as a percentage of the breaking strength of new, unused rope.

Again – the Working Load Limits shown are guidelines, not specifications, and are for non-critical applications. They do not apply if the rope is to be used for overhead lifting, or if life, limb, or property is at risk. In these cases – or for more complete information on determination of Design Factor and WLL – please refer to the Cordage Institute “Safer Use of Fiber Rope”.