(Extracts courtesy of A.N.T.A. publications, Ranger Hope © 2008 www.splashmaritime.com.au)
Types of Ropes & Wires
Safety Precautions when Working with Ropes
Care and Maintenance
Strength of Rope
Knots, Bends & Hitches
Types of rope and wire
The basic materials are:
- Natural Fibres
- Synthetic Fibres
- Steel Wires
Some of the above may be found to be used in combination.
The term 'rope' is used for both Fibre and Wire ropes.
The term 'cordage' is used to denote Fibre ropes only.
These can be made of natural (vegetable) fibres such as Hemp, Sisal, Manila, Coir and Cotton,
manufactured (synthetic) fibres such as Nylon, Terylene or Dacron, Polypropylene, Polythene and Kevlar.
Making of Cordage
The process of ropemaking consists of taking Fibres which are short lengths, in the case of vegetable or Polypropylene, and spinning into Nettles. These are then twisted into long lengths to form a Yarn. The yarns are twisted to form a Strand and then laid up to form cordage.
In the composition of synthetic cordage, the nettles are formed from long continuous filaments.
To prevent the rope unlaying, the strands are laid up in the opposite direction to the yarns.
Example-If the strands are laid up right handed during manufacture, then the yarns in the strands will be laid left handed, the nettles would be right handed.
We will next look at the LAY of the rope which may be hard, soft, left hand and right hand.
Types of Construction (Lay)
This is the most common type, 3 strands laid up right handed, available in sizes 3 mm diameter upwards.
This is less common nowadays, 4 strands laid up right handed over a central heart. It is 11% weaker than equivalent sizes in 3 strand.
Cable Laid (or Water Laid)
This consists of 3 x 3 stranded right hand ropes laid up left handed. Very elastic and may be used as a spring for towing.
Solid braided ropes are constructed from either 12 or 18 strands, braided together, normally over a central core. Available in sizes 3 mm - 12 mm diameter.
This is the plaiting of 4 left hand and 4 right hand strands, resulting
in a tough, kink resistant rope providing increased flexibility wet or dry.
16 mm and upwards for towing and mooring lines.
Some natural fibres used for cordage are:-
Hemp:- was used almost exclusively in rope manufacture, but is now generally found in the smaller classes of line, most of which are of the tarred variety. It does not swell when wet.
Coir:- sometimes referred to as 'grass rope'. It comes from the coconut palm and soon rots if stowed away wet.
Manila:- remains pliable when wet and is usually employed where a rope with a good 'SPRING' is required. Of little value for lifting as it can stretch 40% to 50%. Useful attached to a towing wire or as a warp as it will float.
Cotton:- was once popular on yachts because it is soft however it is expensive and has been superceded by the great range of special purpose synthetics for yachting.
Sisal:- cheap rough rope.
Jute:- cheap smooth string.
Steel Wire Rope (S.W.R.)
The chief component parts of a stranded wire rope are shown below in illustration
Flexibility is introduced into a wire rope either by building the strands around a fibre heart, and the wire in each round a fibre core, or by building the strands around a fibre heart and increasing the number of wires in each strand while reducing their individual thickness.
Properties of Steel Wire Rope
· Type of Core
This identifies the 'MAKE-UP' of a rope and shows the number of strands in the wire, then the number of wires in the strand.
Above is shown a 6/7 (the 7 representing 6 over 1), ie 6 strands of 7 wires each.
Ropes are referred to by diameter. The correct way to measure is shown below.
Generally 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.
A. Fibre Cores
Generally hemp, jute, polypropylene. They provide a resilient foundation for the strands and are used for ropes not subject to heavy loading. Used where flexibility in handling is required.
They are inadequate where wire rope is subjected to heavy loading, prolonged outdoor exposure, and crushing on small drums and sheaves.
Natural fibre acts as a good sponge, but if re-lubrication is not adequate, rot and rust may form.
Synthetic fibre is rot proof, chemically resistant and more flexible than wire cores.
B. Wire Strand Cores
Used chiefly for standing ropes (Guys or Rigging). They offer high tensile strength, and have a greater resistance to corrosion failure due to larger wires in the core.
This refers to the way the wires in the strands, and the strands in the rope are formed into the completed rope.
Steel wire ropes are conventionally produced with Right Hand lay unless special circumstances require Left Hand.
Ordinary Or Regular Lay
Right Hand Ordinary Lay (R.H.O.L.) wires laid left handed, strands laid right handed.
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. Not as easy to handle as ordinary lay.
Non Rotating Wire Rope
The outer strands may look like a LANGS LAY formation, but all the wires and strands are very much smaller in size. The inner strands are arranged so that any tendency for the rope to rotate under load is reduced to a minimum. It is very flexible and well suited to crane whips (runners).
Safety precautions when working with ropes
1. Don't Overload
The load applied should never exceed the minimum Breaking Force or in the case of lifting equipment, the SAFE WORKING LOAD (S.W.L), see later section on S.W.L's of cordage, wire, etc).
2. Avoid Shock Loads
Sudden strain can part ropes that would normally be capable of supporting the same loads under steady pulling conditions.
3. Avoid Kinks
Never load a kinked rope or pull it through a block, as the rope is weaker at the kink and likely to part at that point at a much lower breaking strain.
4. Avoid Knotting
For the purpose of forming an eye this will reduce it's strength by 50%. Splice the rope in the normal manner, reduction in the strength of the rope due to splicing is about 10%.
5. Avoid Sharp Angles and Bends
Chafe and wear account for most rope failure. Never use a smaller sheave than is recommended for the size of rope you are using.
6. Do Not Drag Ropes
Do not drag over sharp, rough or dirty surfaces, as abrasives can penetrate the rope and damage the fibres.
7. Reverse the Ends
Equalise wear over the entire length by reversing the rope where possible or cutting off ends to move wear points.
8. Listen to the Rope
Natural fibre ropes tend to give a warning when they are reaching breaking point by the creaking sound they emit.
Synthetic fibre ropes reduce dramatically in diameter and most do not make a sound before breaking. Due to their elasticity they have a whip effect and it is essential that all personnel are working clear of the rope.
9. Broken wire strands
Broken strands of wire can slice through the skin of a person handling the wire. It is therefore essential to wear gloves while doing so and also stray strands should be inspected and then cut off to ensure they do not protrude.
10. Bight of the Rope
Never stand in the bight of a rope
Care and Maintenance
Uncoiling New Cordage
Below 48 mm the rope can be taken direct from the inside of the coil. This will maintain its protective wrapping. With right handed rope the coil should be stood on the end which will allow the rope to be taken off left handed from the inside.
Uncoiling the rope in the wrong direction will insert twist and increase the danger of kinking.
Always coil ropes in the direction of Lay,
ie., Left hand (L.H.) lay anti-clockwise
Right hand (R.H.) lay clockwise
Two methods of finishing coils are shown above.
To avoid problems in paying out a rope, it should be flaked down, as above. This avoids it becoming tangled or kinked.
A fancy way to finish a rope is with a Flemish Coil. It SHOULD ONLY be used for tidiness and never when required to render quickly through a block, see above.
Before cutting the desired length of rope, whippings should be applied close to each side of the intended cut. Failure to observe this precaution can cause excessive unlaying of the rope.
Care and Maintenance
Chemicals:- Natural fibre rope is severely damaged by chemicals. Synthetic ropes are much more resistant.
Heat:- Excessive heat will melt synthetic ropes and make natural ropes dry and brittle.
Storage:- Store ropes in a well ventilated dry atmosphere away from heat, strong sunlight and corrosive substances. Natural fibre rope will quickly rot if stowed away wet. Always dry out before storing. Keep loose coils OFF the deck.
Cleaning of Ropes
If a rope has been used in mud, sand or grit, it should be cleaned thoroughly before being stored. To wash rope, hang it up in loose coils or flake it out on the deck and hose with fresh water.
External Damage:- Abrasion, cuts, discoloration, bleaching, burns, (soft spots indicate badly worn rope).
Internal Damage:- Dry rot or mildew cause change in colour of fibre strands, broken fibres, powdered fibres, broken central core.
Inspection Of Wire
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.
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.
Open the lay.
1. Check internal lubrication.
2. Degree of corrosion.
3. Indentation caused by pressure of wear.
4. Presence of broken wires.
An accurate log should be kept of inspection dates, rope condition, end for ending, replacement, etc.
Broken wires are usually a result of fatigue and wear.
Marine Order (part 32) "The total number of broken wires visible in a length of S.W.R. equal to 10 times it's diameter should not exceed 5% of the total number of wires constituting the rope".
Strand distortion is generally a result of damage caused by kinking, crushing, bad nips or other violent treatment. Commonly found in berthing hawsers, and ropes which have to be worked in adverse conditions.
Occurs both internally and externally. Caused by:-
a. Friction over sheaves, leads, sharp or rough objects
b. Dirt, dust, grit lodging within strand wires.
a. Deposits of fine brown powder between strands
b. Flattening of internal surfaces of individual wire.
Generally caused by lack of lubrication. When wire rope is under tension, the fibre heart and cores are also compressed, releasing oil to overcome friction.
Strength of Rope
Synthetic Fibre Rope against Natural Fibre
1. Greater strength, size for size.
2. Greater elasticity or stretch.
3. Better shock absorption.
4. Better abrasive resistance.
5. Greater flexibility, ease of handling.
6. Less water absorption.
Note: (2) not of great value in lifting gear.
1. Outer surface presents a smooth slippery surface. May cause slip and failure of any bends and hitches. It is essential that the 'TAILS' of these are seized to the standing part.
2. When splices are made, an additional tuck with all strands is recommended.
Rough comparison size for size.
Manila - breaking force 4 tonnes
Polyethylene - breaking force 6 tonnes
Monofilament - breaking force 6 tonnes
Polypropylene - breaking force 7 tonnes
Polyester- breaking force 8 tonnes
Nylon - breaking force 9 tonnes
Stress denotes the load put on material, and strain is the molecular disturbance made evident by a change of shape or a fracture of the material due to the stress which has been applied. 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), 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 (usually six).
Their relative order of strength is Coir, Sisal, Manila, Hemp, Polyethylene, Polypropylene, Terylene and Nylon.
Splicing a rope reduces its strength by at least 10%. Knots reduce a rope's strength by at least 50%. The ultimate strength of fibre ropes depends much upon the quality of fibre and the process of manufacture.
The diameter of fibre and steel wire rope is in mm. The safety factor of fibre and steel wire rope is 1/6. Thus S.W.L. can be taken to be 1/6 of the breaking strength for fibre and wire rope. (See the table on the next page).
Approximate S.W.L. Rope = D2 x F kgs.
D is diameter of rope in mm.
F is a factor of safety.
Polyamide (nylon) < 50 mm
Polyamide (nylon) > 50 mm
The safety factor is taken as 1/6
The S.W.L. is taken to be (1/6 x B.S.) tonnes
30 mm Nylon S.W.L. = 3 x 302 = 2700 kgs
15 mm Wire (6 x 24) S.W.L. = 8 x 152 = 1800 kgs
It is common practice to allow a 'Factor of Safety' of 6 in general marine work for both fibre and wire rope.
Knots, Bends and Hitches in common use
KNOT - is the intertwining of the end of the rope with a portion of the rope.
BEND - is the intertwining of the ends of two ropes to make one rope.
HITCH - is the attachment of a rope to a post, pole, ring, hook or other object or standing part of another rope.
SPLICE - is the joining of the ends of two ropes, or the end of the rope with the body of a rope, by weaving the strands over and under the strands of the other part.
Parts of the Rope
Standing part - The part of rope taking the strain.
Tail - The part of rope used to make fast, or the unused part.
Bight - The loop between the standing part and the tail.
Reef knot or Square knot
Widely used for lashing when a secure knot that is easily undone is required. Used for joining two same size pieces of cordage.
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.
May be used to put a temporary eye in a rope, secure a safety line, join two hawsers.
Sheet or (Becket) Bend
Used for joining two differing size pieces of cordage.
Double Sheet Bend
Used for joining two differing size pieces of cordage more securely.
Joining 2 hawsers. Probably strongest of all, knotted hawser bends.
Secures end of a line under tension. Can be preformed and dropped over a post etc. Can be used where a small rope is to be secured to a larger rope or a spar and the end kept free. It should never be used where high load is involved – it will jam and never come undone.
Similar to a clove hitch but with an extra turn. May be used to take a strain along a spar. Used to secure a rope tail to a larger rope or spar when the direction of pull is along the rope/spar in one direction only. It can be used with chain or wire rope to hold the strain while a riding turn is cleared from a winch.
Round Turn and 2 half hitches
Common method of securing a line to a bollard, spar or ring.
Fibre Rope Splicing
Splicing fibre or wire ripe is a skill that can only be learned through practice. For a comprehensive treatment of splicing, consult one of the many books on marlinespike seamanship.
Before splicing - seize the ends of unlaid strands, and seize the rope at the point to which you plan to unlay it.
An eye splice is formed by unlaying the end of a rope, then turning the end back to from an eye, and tucking the separated strands into the standing part. If splicing round a thimble, tie the rope securely to the thimble with light twine.
Coming alongside and leaving a berth is one of the common manoeuvres you will make. The secret is:
· Knowing your boat – its stopping and turning characteristics.
· Being competent in the basics of handling your vessel.
· Being prepared – having fenders and mooring lines ready and a clear plan in your mind. If you have crew, let them know what you intend and their role in the operation.
We will confine our discussions from now on to planing boats with outboard motors. Don’t forget what we have already said about displacement hulls with fixed propellers and conventional rudders. They will behave very differently to our 5 metre centre consul with a 50 hp outboard. For the moment we will leave wind and current out of our procedure.
From a position alongside the jetty, our mooring lines may look like this:
For a 5 metre vessel, a head and stern line as shown may be sufficient. They will keep your vessel from moving out from the jetty especially if you take your stern line to the outside bollard. This gives extra length and a better angle. In some conditions these lines may not stop your boat from ranging lengthways along the jetty. If this is the case we use spring lines. These not only solve our ranging problem but your forward spring is the most useful line when berthing and leaving the jetty.
Note that your forward spring comes from the fore port of your boat and stops it from ranging forward. Your aft or back spring comes from the back of your boat and stops your boat from ranging backwards.
One problem is that you seldom have enough cleats in the right places on a small boat to handle all of these lines. The other problem is they are usually so small that they can’t be used for two lines at a time or take more than one turn around them.. You will have to make do with what you have.
Mooring lines should be of a suitable size for both strength and to allow a couple of turns on the cleats of your boat. Splice an eye on one end and melt the ends of the fibre on the other. They should be in good condition without knots or splices so they will run freely and not jam on obstructions on the jetty pile or bollard. They must be long enough to provide some ‘give’ as your boat moves gently, and to allow for any change in the tide.
How you leave the jetty will depend on many variables such as wind, the size and weight of your boat, current and the extra pair of hands that a competent crew can give. Here are a few suggestions to start you off.
What not to do: Don’t drop all of your lines and try to drive forward and away from the jetty. Remember it’s the stern that moves first and it will hit the jetty. Even worse it you are alongside an expensive large vessel!
What not to do!
Use a headline (bowline): Shorten your headline up and rig it on the bight. This means you put the spliced end on your boat and run the line around the jetty bollard and back to the boat. After starting your engine, let go your other lines, and go astern with your propeller turned away from the jetty. Your headline will hold you while your stern is pulled away from the jetty. When angled up far enough, go back to neutral while the headline is let go and then reverse away. The friction of two wraps around the jetty bollard should allow you to hold the other end in your hand. When you let the tension off it will run clear and you can retrieve it from the front cleat when well clear of the jetty.
Using a headline to leave a berth.
Use a forward spring: Rig your forward spring on the bight before letting go your other lines and go ahead at idle with your propeller away from the jetty. Your spring will stop you going forward and your boat will settle in alongside. (Your stern can’t move and so neither will your bow!) With the correct amount of rudder it will sit there quite happily while you take off your other lines.
Holding alongside with a forward spring.
Leaving a berth using a forward spring: Remaining ahead at idle, turn your propeller toward the jetty and the stern will pivot away. At the desired angle, come to midships and reverse out letting the spring go at the same time.
Leaving berth using fwd spring
This would be the most common way to take our conventional displacement boat out also.
When backing out use a positive amount of power once your line is clear to stop wind and tide taking over. Remember the inefficiency of your propeller in astern, but also that you can steer quite efficiently.
Now that we are away from the berth, how do we get back in? Try following the steps outlined below. You can adapt things for conditions later.
· Prepare your mooring lines and check the jetty for a suitable bollard.
· With outboards and stern drives you can berth equally well port or starboard side to. If by yourself, berth on the side of driving position.
· Approach the jetty at an angle determined by the amount of room you have (ie. other boats on the jetty).
· You should be in gear until the last moment to give you steerage but at a speed that will allow you to stop in time.
· At the last moment, engage neutral, turn your propeller to the jetty and then apply astern power. This will stop your boat and pull your stern alongside.
Depending on conditions and the number of helpers, you can then make yourself secure.
Coming alongside with an outboard motor
If conditions are difficult or you are by yourself, you will need to use a spring. It will work from any near side cleat, but the shoulder one works best if you have one. If you haven’t, use the stern cleat as show below.
Estimate the length you will require (about half the length of your boat) and tie if off to the cleat leaving the spliced end free. When you stop your boat, aim to have the driving position next to the bollard so you can drop the eye over it.
Ease astern gently until the line is under tension and while staying in gear adjust the angle of your motor so your boat sits snugly alongside as it did when we were leaving. It will stay there while you put on the remaining lines. You can then come out of gear and shut your motor down.
Using fenders can save your boat, and perhaps others in the area, in case of a ‘crash’ landing. Have them secured and ready before you berth. This is especially important if you are coming alongside another vessel. In this case, follow the same procedures as above. There will probably be people on the other boat to lend a hand.
Anchoring is another routine task which shouldn’t present any difficulties but often does. The problems can arise from lack of knowledge, but more often from lack of planning and checking the simple things. Your anchor is also an essential part of your safety equipment and may well get you out of trouble one day. Let’s look at the basics of anchoring a small boat.
Anchors: Of the many types available, only a few are suitable for small boats. The C.Q.R. or plough, and the danforth are designed for sand and mud. The danforth is easier to stow because it lies flat. The plough is an excellent anchor best stowed hanging over the bow roller. If you are anchoring in rock and reef, a reef pick is the best choice because the arms will bend if sufficient pressure is applied and it can be dragged free. It is sometimes impossible to free either of the other two in reef so take care. Losing your anchor can spoil a good day and may put you in danger later in the day if something else goes wrong. A sea anchor or drogue is also a handy piece of equipment in emergencies as we will see later.
Danforth anchor CQR plough anchor
Reef pick and Drogue or sea anchor
Your anchor must be large enough to hold you in poor conditions but at the same time be comfortably handled and stowed. Seek advice on size if you are not sure, but common sense and experience should tell you if the anchor you have is suitable.
No anchor is suitable for all situations and so we need to choose the one which will do the job best according to the most common type of bottom we will be anchoring in.
Anchor cable: You have two choices which will depend on your needs and the size of your boat.
Chain is the best choice because it is strong, heavy and can be used in conjunction with the gypsy on your windlass if the size of your boat warrants one.
The chain should be attached to your anchor with a shackle of the same size as the chain and the shackle should be moused (wire the pin to the body of the shackle) to prevent it from coming undone.
Make sure that the inboard end of the chain (the bitter end) is secured to a strong point of your boat!
Rope is commonly used as anchor cable on small boats. Choose a synthetic (man made fibre) rope as it is stronger and doesn’t rot. The size (diameter) should suit the weight and windage of your vessel. You should also have about four metres of chain shackled to your anchor and the rope shackled and moused to the chain through a thimble spliced into the rope.
Thimble spliced into rope
Once again – don’t forget to tie off the inboard end!
The chain prevents chafing on the rope and provides weight to hold the shank of the anchor on the bottom. Most inexpensive synthetic ropes float and we will see how this would reduce the holding power of your anchor.
The length will obviously depend on the depth of the water you intend anchoring in, but it should be at least four times the depth of the water.
Stowing: Your anchor and cable should be stowed so that it is ready for immediate use in the case of an emergency. This means that:
· The cable should be shackled to the anchor and secured at the bitter end to your boat.
· If the anchor is stowed to prevent it falling over the side in choppy seas it should be easy to detach.
· Cable should be coiled or flaked so that it will run out easily without tangling.
How your anchor holds:
Anchor action – plough.
Anchor action – danforth
It is impossible for the weight alone that you can comfortably lift to hold a boat a great many time its own weight against wind and wave action.
You can see how the weight of chain helps and how the length of the cable compared to the depth of water (scope) is vital to keep the cable pulling horizontally.
In the diagram above you can see that your cable develops a curve. Chain will naturally do this and you can secure a weight on a rope cable to get the same effect. As your boat moves, most of the work is being done by the cable being lifted and pulled through the water before the weight goes onto the anchor.
A constant steady pull which straightens your cable must pull the anchor out. You should notice your cable continuously straightening and then curving which means your boat is ‘riding at anchor’.
Coming to anchor:
When coming to anchor, consider the following points:
· Is the anchor ready to let go?
· Am I anchoring in sand, mud, shale or rock and is my anchor suitable? Shale has poor holding power and beware of rock and reef.
· What is the depth of water – do I have sufficient cable and is there enough water to allow for tidal movement?
· If the wind changes, do I have swing room and would it put me in danger of being blown onshore if my anchor drags?
· Are there other boats in the area that could cause problems?
Once you are satisfied, approach your spot into the wind (or current) slowly, and proceed as follows:
· Stop your boat and let go the anchor.
· Allow your boat to drift back as you play out the desired amount of cable. Don’t let your chain pile up on top of your anchor.
· Secure the cable. You should feel the anchor grip and bring your bow into the wind or current.
· If it is not holding your cable will be straight and if you put your hand on it, you will feel the anchor dragging over the bottom.
· Periodically check your position relative to other vessels or land marks.
· If using rope cable, make sure it is not chafing where it goes over the bow.
Remember, your anchor is only intended as a temporary mooring. No anchor will hold indefinitely as conditions change and so it follows that someone should be on board to continually check your position and take further action as required.
When anchoring in reef, especially coral reef, be aware of the damage your anchor and chain does. Try and anchor in sand to windward and hang back onto the reef. This will prevent damage and ensure you can retrieve your anchor when it is time to go.
Retrieving your anchor:
The following are some common sense tips which may help when you are hauling up your anchor:
· Always start your motor before you haul the anchor.
· Drive forward to take the strain off the windlass as you are retrieving the cable keeping your bow into the wind..
· Stow cable and anchor securely ready for emergency use.
Stowing of anchor