Teacher Discussion Forums

About right-handed and left-handed

Among the several meanings of ‘right-handed’ and ‘left-handed’ other than the ones that we use in such sentences as ‘He is left-handed.’ , there are ones indicating ‘clockwise turning’ and ‘counter clockwise turning’. In these meanings, I hear we can say such things as ‘This screw is produced in a left-handed process.; The threads of this screw are cut in counter-clockwise direction.’ I’m now writing about specially produced ropes and I thought if I wanted to talk about a rope which is produced with counter-clockwise twisting, I should write ‘a left-handed rope’. One of my British friends said I was wrong and said in the particular case of talking about ropes, threads, strings, unlike in the case of screws, a left-handed rope means a rope produced with clock-wise twisting (right-turning) and vice-versa. I wonder if it’s true. Someone! Please help! Thanks in advance.

Care of Webster:

Main Entry: left-hand·ed
Pronunciation: -'han-d&d, -'tan-
Function: adjective
Date: 14th century

5 a : having a direction contrary to that of the hands of a watch viewed from in front : COUNTERCLOCKWISE b : having a spiral structure or form that ascends or advances to the left <a left–handed rope>

Iain

Hi ,
An interesting question, and one that deserves a proper answer.

A traditional ‘hawser-lay’ rope is constructed of three strands. Countless fibres are twisted to form yarns, the yarns are twisted to form strands, the strands form the rope. The twist of the yarns is opposite to the fibres and the eventual way that the strands will be laid up. A right-hand rope has strands twisted to the right, but these are composed of yarns twisted to the left, composed of fibres twisted to the right.

In a normal lay the strands are twisted in a right-hand spiral, with the direction of the lay viewed away from one’s body. A right-hand lay has the strands twisted so that they spiral away in a clockwise direction. Ropes are occasionally made with a left-hand lay – but usually for a special purpose. The same principle applies to all ropes, even those made of other materials (steel, for example) or where the number of strands is increased (7, 9 , 19 strand, etc.) When splicing, the join is made by tucking against the lay.

From the ‘bitter end’ of the rope , viewed back towards the body, the spiral is from left to right – just as it would be on a normal right-hand threaded screw or bolt.

However, not all ropes follow this pattern. A multiplait rope has pairs of strands tucked against each other, some left and some right – hence a ‘plait’. In a multiplait the strands are not laid. A multiplait has no inherent twist and cannot be described as ‘laid’. A ‘core and sheath’ (kernmantel) rope has a core that is laid with a sheath that is plaited. The rope does not appear to be laid, but the inner core does have a twist, and so (as any climber will tell you) has to be coiled against the lay to avoid twists. It is also possible to have a braided rope made with a braided core – it has no lay and no twist.

Peter Weston