Fibres used in rope making

When I first started driving Land Rovers in 1960, all that was available to me were natural fibre ropes for recovery. For steady pulls and on-road towing they were fine, but there were disadvantages.

The most common natural fibres that were available in years gone past were manila and sisal.

Manila consists of the sheath fibres from the leaves of a type of banana tree, Musa textilis, indigenous to the Philippines. The leaves are picked when the plant is three years old and the stems are cut into narrow strips 20 - 30 mm wide and about 5mm thick. These are scraped against blunt knives. In this way the soft juicy parts are removed, leaving the fibres clean. They are then dried and made ready for packing and export. This treatment was first done in Manila, which gave this type of hemp it's world famous name. Manila is also grown in the Sunda Islands (Sumatra manila), India and the West Indies.

The fibres are very hydroscopic and swell considerably in water, where the rope will shrink, stretching again when it dries. A manila rope is identifiable by it's slightly speckled appearance, due to the fact that both darker and lighter coloured fibres are used in its manufacture. A new manila rope is smooth in appearance and slightly shiny, unlike sisal.

Sisal hemp consists of the fibres in the fleshy leaves of the various aloe and agave plants, in particular Agava rigida var. Sisalana, indigenous to the the dry, high, stony plateaus of Central America and first shipped from the small port of Sisal on the north coast of the Yucatan peninsula.

The sisal plant has a long stem and the large, sword like leaves grow in a big rosette near the ground. The leaves are first picked when the plant is three to four years old and are put through a machine which washes and separates the fibres from the fleshy parts. The clean fibres are then dried on racks before being baled for export.

Sisal hemp has long even fibres. New sisal is distinguishable from manila by it's uniform pale yellow colour being duller in appearance to manila. Around the turn of the century sisal growing was introduced into East Africa and later into Sumatra and Java. Nowadays it is grown in many tropical areas, particularly Tanzania and Kenya.

There are other natural fibres as well used in rope making, but none of them are as strong as manila and sisal.

Stronger man-made synthetic fibres

Nylon rope was first used only about fifty - sixty years ago and it didn't take long to cotton onto (excuse the pun). The fishing industry took to it very quickly as nylon fibre rope is unaffected by water, and size for size against manila and sisal it is at least 50% stronger allowing smaller diameter ropes to be used for rigging, fishing and towing.

Synthetic fibres are man-made fibres which are produced entirely by chemical synthesis from simple basic substances. As compared with natural fibres they are of better uniformity and continuity. Fibres made of Polyvinyl alcohol and of Polyvinyl chloride are now almost exclusively made only in Japan.

Nylon fibred rope is very elastic. It can stretch up to about 30% returning to it's original length when the tension is released. This elasticity is particularly useful in certain applications, but also carries with it a certain amount of risk: if a nylon rope breaks under stress it may act like a rubber band in contracting and catapult say, a heavy shackle or part of a towing point back towards the other point of attachment which could be highly dangerous. However, in our off-road field we use this 'Kinetic Energy' to our advantage - with an awful lot of care.

Index [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]

(c)Goodwinch Limited 2006