ROPEWORK ASSIGNMENT: NAME:

Questions One

1. List two types of natural and two types of synthetic fibre ropes and give their characteristics and properties.

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2 Explain the following 'Lay' of fibre rope.

a) Hawser

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b) Braided

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c) Cable

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3. Describe how you would remove a length of cordage from a new coil.

5. When using fibre rope , four things to avoid __________________________________________________________________________________________________________________________________________________________________________________________________________________

6. Explain the uses of the following:-

a) Figure of eight knot

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b) Bowline

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c) Sheepshank

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7. What is the S.W.L. of - (Coxswains only)

a) 20 mm Manila

15 mm Polypropylene

Answers One

5. Explain the uses of the following:-

a) Figure of eight knot

Used as a stopper to prevent the line from running through a block. Does not jam so readily as an overhand knot. Can also be used to keep an unwhipped line from unlaying.

b) Bowline

May be used to put a temporary eye in a rope, secure a safety line, join two hawsers.

c) Sheepshank

Used for shortening a rope.

6. What is the S.W.L. of -

a) 20 mm Manila

Manila formula = D²

= 20²

= 20x20 = 400 Kg

b) 15 mm Polypropylene

Polypropylene formula = 1.8 D²

= 1.8 x 15²

= 1.8 x 15 x 15 = 405 Kg

c) 12 mm 6/24 wire

Practical Activities

1 Visually inspect the ropes on your vessel or at your training institution and determine their condition, based on the knowledge gained in this module.

2 Inspect your mooring ropes forward and aft and determine their SWL and Breaking Strain.

3 Inspect the eye splices on your mooring rope and determine if they have been made up correctly.

4 Practice making the various knots, bends and hitches also splicing in cordage.

Practice an soft eye splice in a piece of cordage.

Questions Two Steel wire rope

1. What are the properties of steel wire rope?

2 Explain 'Langs' lay and where this type would be used.

3 Give some examples of wire rope deterioration.

4 How are rope sizes measured?

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5 List the internal and external evidence of deterioration in wire ropes.

Internal:

External:

6 What should you look for when carrying out an inspection of wire rope?

7 Define:

(a) Breaking Stress

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(b) Safe Working Load

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Answers Two Steel wire rope

1. What are the properties of steel wire rope?

Properties of Steel Wire Rope are determined by:

Size

Construction

Type of Core

Lay

Flexibility

The size of steel wire ropes are referred to by diameter

Construction identifies the 'MAKE-UP' of a rope and shows the number of strands in the wire, then the number of wires in the strand.

The centre core of the rope is named the HEART and the centre of the strands the CORE.

The purpose of the heart is to:-

1. Act as a lubrication sponge.

2. Provide support for strands enabling the rope to keep it's shape.

There are at sea basically 2 types of CORE.

A. Fibre (natural or synthetic).

B. Wire Strand.

The lay of the rope refers to the way the wires in the strands, and the strands in the rope are formed into the completed rope.

2.Explain 'Langs' lay and where this type would be used.

The strands are laid up in the same direction as that in which their constituent wires are twisted, ie., both wires and strands RIGHT HANDED or both LEFT HANDED.

Langs lay makes for a more flexible rope and wears well when used for hoisting, due to wear being spread over a larger area of wire. It can only be used when both ends are anchored and prevented from rotating, (eg., CRANE TOPPING LIFTS), because it is liable to unlay when under stress if one end is free to rotate.

3. Give 8 examples of wire rope deterioration or damage.

Fatigue

Kinking

Spiralling

Crushing

Strand Distortion

Abrasion

Corrosion

4. How are rope sizes measured?

Ropes are referred to by diameter. The correct way to measure is shown below

Wire formula =8D²

= 8 x 12²

= 8 x 12 x 12 = 1152 Kg

5 What factors affect wire rope life?

The basic factors affecting rope life are:-

a Basic equipment design and installation ie., sheave size and drums

b Operating environment. Corrosion - Internal and External

c Wear generally caused by:-

d. Drum, sheaves and obstructions

e. Drum creeping

f. Acceleration and breaking

g. Fatigue

h. Kinking

i. Spiralling

j. Crushing

6 What should you look for when carrying out an inspection of wire rope?

A visual and physical examination should take place at regular intervals. Under normal conditions of use, wire rope can be inspected every 3 months. If a broken wire is discovered, then it should be inspected more often. A thorough inspection is given below.

Externally

1. Inspect termination of rope at the drum and other points.

2. Inspect for broken wires.

3. Inspect for corrosion.

4. Inspect for deformation.

5. Inspect for surface wear.

6. Inspect for defective coiling.

7. Inspect for deterioration due to snatch loading.

8. Inspect lengths that run through blocks, particularly those which lie on the sheaves when the appliance is in the loaded condition.

6. What should you look for when carrying out an inspection of wire rope?

Internally

Open the lay.

1. Check internal lubrication.

2. Degree of corrosion.

3. Indentation caused by pressure of wear.

4. Presence of broken wires.

7 What is S.W.L. and B.S.?

The term BREAKING or ULTIMATE STRENGTH is the load or weight applied to material when testing to destruction. Every item used in rigging has a B.S. (Breaking Strength or Strain), from which a S.W.L. (Safe Working Load) may be found by dividing the B.S. by a factor of safety for the function of the gear.