Rope ropework

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DMS -- G. S. K.

ROPE and ROPE WORK

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TYPES OF ROPE.

Rope may be constructed from natural fibres such as cotton, coir, hemp, manila and sisal

Or from synthetic fibres such as polyamide (nylon), polyester (terylene), polythene and polyproplene or a mixture of some of these synthetic fibres.

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TYPES OF ROPE.

It may also be made from drawn strands of steel wire or a mixture of wire and either natural or synthetic fibres.

Wire ropes for marine use are normally galvanised.

All ropes for marine use are normally laid up right handed (anti-clockwise) and supplied in coils of 120 fathoms (220 m), unless specially ordered otherwise.

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Natural fibres.

Cotton rope is mainly used on yachts, being soft and pliable. Hemp rope is used for small lines and edging sails.

Coir rope is both buoyant and elastic but lacking in strength, normally used for guess warps and when attached to wire rope tails, for mooring springs and tow ropes.

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Natural fibres.

Sisal rope is in general use for gantlines, lashings and moorings.

Manila rope is in general use for Lifeboat falls, cargo handling, lashings and moorings.

Coir, hemp and cotton ropes are no longer much in demand, having been largely superseded by synthetic fibre ropes.

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Synthetic fibres.

Polyamide (Nylon) rope, the most elastic and strongest of all synthetic fibre ropes, resists alkalis, oils, organic solvents and rot. Melting point 2500C.

Mainly used for springs and tow ropes, also used by stevedores for cargo work.

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Synthetic fibres.

Polyester (Terylene) rope with a melting point of 2600C has the highest resistance to fusing of all synthetic fibres. Resists acids, oils, organic solvents, bleaching agents and rot. Mainly used on yachts.

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Synthetic fibres.

Polythene rope with a melting point of 1350C has the least resistance to fusing of all synthetic fibres. Buoyant, it resists alkalis, oils, bleaching agents and rot. Used for loglines and halyards.

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Synthetic fibres. Polypropylene rope is made in three types,

"Fibrefilm", "monofilament", and "staple". The main difference being in the elastic property

of the rope, the least elastic and lightest O{ the synthetic fibre ropes, it has a melting point of 1650C and is buoyant. Resists acids, alkalis, oils and rot.

Main use is for mooring lines. Only spun staple polypropylene should be used for gantlines.

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Preformed Galvanised Steel Wire rope.

Non-flexible galvanised steel wire rope (Iron wire) is manufactured for use as standing rigging (shrouds, stays, etc.), and will have six strands laid up right handed on a wire core.

Seizing wire as used for wire seizings will have six wire threads laid up right handed on a wire core.

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Flexible steel wire rope used for running rigging and moorings, and when attached to fibre rope as tails for springs and towing. May have 6, 12, 17 or 18 strands laid up right handed on a fibre core. The wire threads in each strand will also be laid up on fibre cores. Generally speaking, cargo runners and moorings will contain 6 strands while deck cranes will have more, lifeboat falls are often 18 strand.

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The greater the number of strands and the greater the number of wire threads in each strand, the greater the flexibility of the rope.

Wire ropes are to be discarded if in any length of eight diameters, the total number of visible broken wires exceeds ten per cent of the total number of wires,

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or if the wire shows signs of excessive wear or corrosion or other serious defect.

No chain or wire rope shall be used when there is a knot tied in any part thereof.

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ROPE CONSTRUCTION

Normally, the threads in each strand of a rope will be laid up left handed and the strands will be laid up right handed.

However, non-kinkable rope such as may be used for lifeboat falls has both the threads and the strands laid up right handed.

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ROPE CONSTRUCTION

Hawser laid rope contains three strands laid up right handed.

Cable laid or water laid rope contains three hawser laid ropes laid up left handed. Synthetic fibre and wire cable laid ropes, are laid up on a core.

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ROPE CONSTRUCTION

Shroud laid rope contains four strands laid up right handed on a core.

Plaited rope is supplied where the rope is subjected to twisting viz., log lines and some halyards.

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ROPE CONSTRUCTION

Squareline and multiplait ropes contain eight strands. Two pairs are laid up right handed and two pairs are laid up left handed, so forming a plait.

Six stranded synthetic fibre rope and all wire ropes are laid up on a core.

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Breaking strains and Safe working loads.

To find the breaking strain or the safe working load of any rope, the manufacturer's tables must be consulted. However, in an emergency it is possible to obtain a rough guide to the breaking ,strain of good quality manila rope with the formula ---

The circumference in inches multiplied by itself and the answer divided by three will give the approximate breaking strain in tons.

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A rough guide to the breaking strain of flexible steel wire rope may be obtained with the formula 2C2

(the circumference in inches multiplied by itself and the answer doubled will give the approximate breaking strain in tons).

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The safe working load of manila rope may 'be found by dividing the breaking strain of the rope by six.

The safe working load of flexible steel wire rope may be found by dividing the breaking strain by six.

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Fibre ropes should not be worked through a block whose cheek length is less than three times the circumference of the rope.

Wire ropes should not be worked over a sheave whose diameter is less than sixteen times the diameter of the rope, or five times the circumference of the rope.-

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Under no circumstances will the safe working load marked on any tag attached to any rope or coil of rope

or the safe working load marked on any derrick, block, shackle or other tackle be exceeded..

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Care in the use of rope.

To open a coil of any rope, a turntable should always be used, the rope being taken from the outside of the coil and recoiled clockwise.

Great care must be taken to avoid any kinks getting into the rope.

Fibre ropes are to be coiled down on duckboards, (small lines may be hung up in a ventilated but dry place.)

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Wire ropes should be stowed on reels. Never leave a rope coiled on a bare deck because this prevents moisture from draining which in turn will cause rot or corrosion.

Try not to drag rope over the deck, because it will pick up grit that may later cause serious damage to the centre of the rope from abrasion as the grit works in.

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When no turntable is available, fibre ropes may be uncoiled by taking the end of the rope from the interior of the coil left-handed or anti-clockwise (this will usually be from the bottom of the unopened coil) and recoil right-handed or clockwise.

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Wire rope may be uncoiled by rolling the' coil along the deck and then recoiling clockwise, or better still be wound onto a reel.

No attempt should be made to uncoil a wire rope by taking the end from the centre of the coil.

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A fibre rope that is 'full of kinks or turns may have the turns removed by being thorough footed.

An alternative method of removing turns is to keep one end of the rope on deck while the remainder of the rope is thrown down an empty hold. The end of the rope is then taken to a winch drum end and the, rope hove out of the hold.

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Fibre and wire ropes should whenever possible be kept separate, try not to put wire and fibre ropes on the same pair of bitts or bollard or through the same fairlead

In any case the wire rope must never be allowed to cross the fibre rope, for this causes considerable damage to the fibre rope.

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Unless otherwise stated, all fibre ropes are liable to deteriorate when static, exposed to strong sunlight, chemical fumes, heat, sparks and by abrasion, or when contaminated by acids, alkalis, bleaching agents,, oils and organic solvents.

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In the event of contamination, the rope should be immediately washed with fresh water and closely inspected for damage.

Wire rope is mainly subject to deterioration from moisture and abrasion and should be kept well oiled.

Natural fibre ropes are particularly subject to damage from mildew and rot and must not be stowed away wet.

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Rope should never be stored in the vicinity of steam pipes or boilers.

When stowed on deck, fibre ropes should be covered with tarpaulin canvas in order to exclude damage from weather and strong sunlight.

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Never leave the end of a rope to fray. Put a whipping on.Never use a rope without previous careful

examination of its whole length.

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Care in the use of WIRE ROPE

1. Wire ropes should be regularly treated with suitable lubricants

2. Wire. should never be used directly from the stowage reel, unless the reel is purposely designed to allow direct operation; for if the wire should foul when running, the reel and its supporting frame mat be torn from the deck mountings, causing serious injury to seamen.

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3. Sufficent slack should be taken from the reel to provide adequate to cover all contingencies. Should any doubt exist as to the of slack that will be required, then all the wire should be removed.

4. When wires and ropes are under strain, perhaps in a towing operations persons should stand well back in a position of safety.

5. Sharp angles on wire rope leads should be avoided.

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6. When awkward leads are the only alternative when handling wires,as with cargo winch use, then snatch blocks should be suitably sited and secured sufficiently to prevent them from breaking loose.

7. When wire ropes are turned up about bitts, then the top turns be secured against springing off; by a light lashing.

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8. When wire rope is to be joined to a fibre rope, then the fibre rope be fitted with a thimble, so preventing chafe and wear about the eye

9. Wire ropes should never be led across fibre ropes and allowed to cause chafe.

10. Chain stoppers should be used on wire ropes.

11. Wire on drum ends should not be used as check wires.

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12. Should a wire rope be used as a slip wire, then the parts of the eye should be seized' together and reduced in size to allow passage through the ring of the mooring buoy.

13. When breaking out a new coil of wire, care must be taken, and a turntable used whenever possible

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ROPE MEASUREMENT.

Small natural fibre cordage is measured by the ply (number of threads) or by a number or by weight.

Small synthetic fibre cord is measured by a number.

Ratline and pointline are measured by the total number of threads contained in all the strands, i.e., 9, 12, 15, 18 and 21 threads.

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ROPE MEASUREMENT.

Seizing wire is measured by the gauge (18 to 26) and supplied in seven pound (3.18kg) coils.

All other ropes are measured by the circumference in inches or by the diameter in millimetres.

When measuring rope, if no rope gauge is available, measure round the circumference with a piece of twine and lay the length of twine against a ruler.

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ROPE MEASUREMENT.

To turn circumference in inches into diameter in millimetres:-multiply by 8.

i.e., 2 inch rope x 8 = l6mm rope. To turn diameter in millimetres into

circumference in inches:-divide by 8. i.e., l2mm rope / 8 = 1-1/2 inch rope.

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ROPE MEASUREMENT.

Ropes may be marked by a coloured thread if this is required by the purchaser

There is no standard marking for any particular type of rope

The preformed ungalvanised steel wire rope will be marked with a blue thread

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ROPE MEASUREMENT.

Polypropylene cordages exceeding 12 mm (1-1/2 inch) will incorporate a tape throughout their length bearing at intervals

The words "DOT accepted for LSA" if the cordage has been accepted as suitable for use with life-saving equipment. (M Notice No.698).

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MARRYING.

To marry the end of a dummy gantline to a gantline for the purpose of reeving the gantline through a sheave. Whip and sew the ends of the two gantlines together end on, with the aid of a palm and needle.

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WHIPPINGS.

Plain or common whipping. Temporarily used to prevent the end of a rope

from fraying. Palm and needle whipping. Used to permanently prevent the end of a rope

from fraying. Finish off by tying a reef knot between the strands, using both ends of the seaming twine.

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SEIZINGS.

Flat seizing.Used to secure two parts of rope together

side by side, when the strain on both ropes is equal and in the same direction. Finish off by taking several frapping turns around the seizing, between the ropes and secure the end with two half hitches.

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SEIZINGS.

Round seizing. A more secure version of the flat seizing. A flat

seizing is made of about 12 turns and riding turns are taken on top and made to lie between the first turns. Several frapping turns are then taken around the seizing between the ropes. Finish off with two half hitches.

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SEIZINGS.

Cross seizing.Used to secure the eye of a rope to a

particular place on a rope rove through the eye. i.e., for securing the eye of a lifeline to a davit head span.

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RACKING.

Used to secure two parts of rope together side by side, when the strain on the ropes is unequal or in opposite directions.

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MOUSING.

Used to prevent a shackle pin from working out, or to close the eye of a hook so that nothing can become unhooked from it.

Seizings on fibre ropes and hooks are to be made with spunyarn or marline.

Seizings on wire ropes and shackles are to be made with seizing wire.

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STOPPERS.

Rope stopper.Made of manila or sisal rope it is for use on

natural fibre ropes. Not to be used on synthetic fibre ropes.

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STOPPERS.

Chinese or West Country stopper. Made of synthetic or natural fibre rope. Always to

be used on synthetic fibre ropes, can be used on natural fibre ropes.

**[Note that a stopper MUST always be of the same material as the rope it is used to stopper off. However stoppers should not be made of polyamide (nylon) rope. Use polypropylene stoppers on polyamide (nylon) mooring ropes.]

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STOPPERS.

Chain stopper.Small chain used to stopper off derrick

topping lifts, wire. 'mooring ropes and other wire ropes. The half hitches are separated and the tail is backed against the lay of the wire 'to ensure that the chain neither jams or opens up the lay of the wire.

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STOPPERS.

Carpenter's stopper. An efficient mechanical means of

stoppering off any wire rope. Made in various sizes.

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Home Work 1 List 4 common use fibres for natural fibre ropes

and describe briefly the advantages and disadvantages of each ?

2 Compare and describe the advantages and disadvantages of Nylon and Polypropylene rope ?

3. List the precautions when handling with ropes (Care in the use of rope )?

4. List the precautions when handling wire rope ? 5. How do you distinguish the Breaking Strains

and Safe Working Load for any rope ? 6. Explain briefly how do you determinate the

Wire ropes in use are badly damaged and to be discarded ?

Education

Rope ropework