Rope-making

What are ropes made from?

Ropes have traditionally been made from a range of natural fibres, such as cotton (Gossypium spp.), sisal (Agave sisalana), coir (Cocos nucifera), jute (Corchorus spp.), hemp (Cannabis sativus) and flax (Linum usitatissimum). Nowadays, however, the majority of world-wide industrial rope making uses the oil-based synthetic fibres such as nylon.

Some plant fibres, such as those of flax, are soft and possess a fine sheen whilst others, like those of coir and hemp, are much harder and coarser. However, all plant fibres are flexible, have very little elasticity, have good resistance to damage by abrasion and can withstand both heat and sunlight. Coir fibre from the coconut fruit resists sea-water damage, but like all the natural fibres it will rot if soaked over a long period, due to the action of micro-organisms. The man-made fibres, such as nylon and polypropylene, used for modern rope-making, are stronger than the strongest natural fibre, hemp, and are not damaged by micro-organisms. But the disadvantages of the man-made fibres are that they deteriorate in bright sunlight and melt at a lower temperature than the natural fibres.

Rope manufacture

Most ropes are made by a continuous manufacturing process with the processes of spinning fibres into yarns, which are then twisted into strands and finally ropes on separate machines. There are still a number of firms in the UK, as well as in the developing world, who make rope by the traditional method, the rope-walk. This method is considered more versatile because it is able to produce a greater selection of rope widths.

The rope-walk

All rope-walks consist of a 'twisting machine', carrying several revolving hooks and a 'sledge', with one fixed hook. Groups of yarns run between these two sets of hooks which can be up to 300 m apart. The revolving hooks are turned either by hand or by a small motor, twisting the yarns together to form a strand. As the twisting continues, the yarns begin to shrink, pulling the sledge down the room, until they are as highly twisted as possible without kinking. A grooved tool called a 'top' is inserted between the strands near to the sledge to keep them separate while the twist is put in. The top is then moved forward along the strands away from the sledge and force stored in the tight twist given to the strands then begins to turn the hook attached to the sledge. This hook turns in the opposite direction to the revolving hooks, causing the strands to twist around one another and form the rope. This is called 'laying' the rope.

There are a number of rope-walks preserved in the UK, notably at Chatham Dockyard, where up to 500 tonnes of finished rope are produced per week from natural or synthetic materials. The last commercial rope-walk belonging to the Bridport rope-making firms of Dorset closed down as recently as 1970. Reminders of the UK industrial history of rope-making remain in street names such as 'Rope-makers Street' in the City of London and 'Rope-Walks' all over the country especially in the ports.

Different types of rope

According to the method of construction, ropes are classified as hawser-laid (the most common type), shroud-laid and cable-laid. Hawser-laid ropes are made from three strands of the twisted yarns and are produced in sizes from 2.5 cm diameter upwards. Shroud-laid ropes start at size 3.8 cm and contain four strands, with one central strand about which the others are twisted. Cable-laid ropes are made from three or more hawser-laid ropes and possess greater elasticity and flexibility. These are the heavy industrial and naval classes of rope produced by manipulating a number of yarns. Twine, which is two or more yarns twisted together, and nets are also produced from natural and oil-based synthetic materials, and these find many applications in the modern world.

History

People, as hunters, farmers, craft workers, traders and soldiers, have used ropes for many purposes throughout their history. Ropes are depicted in Spanish cave paintings dating back 20,000 years. Examples of Egyptian ropes from 2600 BC and ropes carried by the Roman legionnaires can be seen in museum collections today. The earliest ropes in Britain were made from twisted strips of lime bark (Tilia spp.) The unfortunate 'Pete Marsh', a body found in an ancient peat bog site in England, was strangled and bound with a knotted rope of Iron Age workmanship. The Incas of Peru slung rope-ways across chasms and kept trading accounts by means of knotted ropes. Sea-traders and navies have always relied on ropes to control large sheets of sail.