Rope

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Natural Fibres

Fibre ropes have been used in theatres for hundreds of years. The most commonly used material for many of those years was hemp due to its wide availability. Since hemp was made from the leaves of the cannabis plant it’s use (as rope) in recent years has become less common.

The term “hemp” however has survived and theatres with a fly tower but no counterweight system are still referred to as “hemp houses”. Furthermore you will hear both the staff and students at the Academy refer to some of our flying bars as “hemp sets”.

In reality our “hemp lines” are all made from Manilla.

Manilla is the hard fibre from the leaf of the Abaca plant from the Philippines. It has the right quantities for stage rigging which are strength, cohesiveness and pliability. Grade 1 should be used for theatre applications.

Another natural fibre commonly used is Sisal, which is not as strong as Manilla. It is made from the leaf fibre of the Agave plant and is generally cheaper than Manilla. Sisal is not recommended for theatre rigging by the ABTT.

However, just because we cannot use Sisal for suspension of loads, it does not mean it has no use in the theatre. You will find numerous lengths of sisal rope in the rope cupboard on the flyfloor and on the pegs of the Prompt Side Flyfloor. These ropes are useful for breast lines, brail lines, general hauling lines etc.

Make sure you can tell the difference between Sisal and Manila, and as always, if you are unsure please ask.

Fibre Rope Construction

From ancient times up until the Second World War rope was made the same way. Natural fibres from the leaves and stalks of plants such as the Abaca Plant, Agave Plant and Hemp Plant were obtained by beating the leaves and stalks to remove the pulp. The residue was then combed to leave only the fibres. It is this combing that determines the quality of the finished rope. If the process is not performed thoroughly the rope will have dark course fibres running through it and will not be as strong. Top quality ropes are lighter in colour and have uniform fine fibres.

Once the fibres have been isolated they are fairly short, they must now be twisted tightly together to grip each other by friction.

To make Right Hand Lay rope, small bundles of fibres are twisted together to make Right Hand Lay yarns. These yarns are then twisted together the opposite way to make left hand strands which in turn are laid up to form Right Hand Lay rope. It is the alternate direction of the twists that holds the rope together and gives it strength.

Lay

Most ropes are “right hand lay” and all the ropes you will find in the Academy are of this type. This means that the strands of the rope have been layed clockwise when it was formed.

If you look at the end of a rope you will the strands of the rope receding clockwise (to the right). If you look from the other end of the rope, still see strands of the rope receding clockwise (to the right). Therefore the lay of the rope has nothing to do with the observer’s viewpoint but is a property of the rope itself.

We can draw a simple comparison with the thread of a screw, which does not change with an observer’s position.


Natural Fibre Rope Care

Natural fibre ropes such as Manilla lose a certain amount of their strength over time. Heat humidity and UV light all combine to dry out the oil, which is impregnated into the rope when it is made. If the rope does dry out it becomes brittle and easily broken. Chemicals such as detergents, oils, paints and chemical salts all damage Manilla. Regular inspection of all your lifting equipment is essential to maintain a safe working environment.

Coiling and Finishing

Coil.jpg


With Right Hand Lay rope coiling must always be done clockwise. Whether the coiling is done on the floor or in the hand is unimportant so long as the finished coil is tidy and easily uncoiled.


Coil clockwise until you run out of rope. Take the last loop off and reverse it so that you have a loop in your hand instead of the tail, which is now held with the main coil. Wind the loop around the rest of the coil tightly quite near the top then push the final small loop through the coil as shown in the final diagram.

You can now hang the rope coil on a cleat or peg. (Rope must be stored hanging and not left on the ground.)

If you need to hitch the rope to something then this loop system isn’t much use. Just wrap the tail end round and round and push the tail through the loop instead.

It’s a little difficult to explain on paper, I’ll show you and you need to practice.


Figure of eight coil

Coiling as a figure of eight almost eliminates all problems of kinking, however, as the coil cannot hold it’s shape it must be kept laid out on the floor. Sometimes a spot line with a large amount of travel will be laid out on the flyfloor in a figure of eight coil to minimise the risk of a kink jamming in the pulleys during a cue.



Man Made Fibres and Synthetic Rope

Man made fibre ropes made their debut towards the end of the Second World War and put to an end 5000 years of natural fibre ropes monopoly.

More and more synthetic alternatives to Manilla rope are appearing on the market. Size for size they are lighter, stronger and cheaper than ropes made from natural fibres. They do not rot if left wet and they take a range of colours well.

Hempex is a synthetic rope on the market, which is an extremely good attempt to make a synthetic rope appear and behave as a natural fibre rope. The Academy has a couple of Hempex counterweight control lines. It is a 3 strand, right hand, hard lay rope with the appearance of old style cotton hemp. It is easy to splice and is soft to the touch. It is strong, does not heat up too much when running through your hands and does not leave the operator with a handful of “skelfs” like Manilla does.

There are other kinds of synthetic rope we use which are not made to mimic their natural fibre cousins. They are the types of rope that rock climbers, cavers, abseilers etc use. These ropes are made from a core which has number strong fibres and these are protected by the outer sheath which is the part we see.

The ropes used with our rope access equipment and the fall arrest equipment are all synthetic. These ropes generally are extremely strong and durable and are either static or dynamic depending on their intended use.


Dynamic Rope – Traditional climbers rope used where there is an expectancy of shock loading. It is designed to stretch when placed under load and can therefore absorb much of the force of a fall or sudden load.



Static Rope – Abseiling and rope access rope where the stretching properties of dynamic rope would make it difficult to ascend or descend a fixed line rope. The rope is constructed pre-tensioned which eliminates much of the stretch. It still has some elasticity under load but should never be used as a safety line in a fall arrest set up.