Handling precautions for synthetic man-made ropes and hawsers
Precautions for synthetic man-made ropes and hawsers
Although natural fibre ropes are still widely used throughout the marine
industry, they have been superseded by synthetic fibres for a great many
purposes. Not only do the majority of synthetic ropes have greater strength
than their natural fibre counterparts, but they are more easily obtainable
and at present considerably cheaper.
Ropes may be of a right-hand lay or left-hand lay, but the most common
is right-handed. It is essential to realise that each of the components
is turned (twisted) up in an opposite direction to that of its predecessor,
e.g. in right-hand lay, strands are laid up right-handed (clockwise), yarns
laid up left-handed, and fibres laid up right-handed.
Mooring ropes stowed on drums
Handling precautions
1. The mariner should carefully inspect a rope, both internally and externally,
before it is used. Man-made fibre ropes show deterioration after
excessive wear by a high degree of powdering between the strands.
2. Ropes should be kept out of direct sunlight. When not in use, they
should be covered by canvas or other shield, or, if the vessel is engaged
on long sea passages, stowed away.
3. When putting a splice in a synthetic fibre rope, use four full tucks, followed
by two tapered tucks (strands halved and quartered).The length
of the protruding tails from the completed splice should be left at least
three rope diameters in length.Any tail ends of strands should be sealed
by tape or similar adhesives.
4. A stopper should be of the same material as that of the rope being
stoppered off, and should preferably be of the ‘West Country’ type.
The one notable exception to this rule is that a nylon stopper should
never be applied to a nylon (polyamide) rope.
5. A minimum number of turns should be used when heaving manmade
fibre ropes about winch barrels or capstans. Friction-generated heat
should be avoided, and to this end no more than three turns should be
used on drums.Where whelped drums are being used, it may be necessary
to increase the number of turns so as to allow the rope to grip; if
this is the case, then these turns should be removed as soon as possible.
6. Never surge on man-made fibre rope. Should it be required to ease
the weight off the rope, walk back the barrel or drum end, as when
coming back to a stopper.
7. When making fast to bitts,make two round turns about the leading post,
or two turns about both posts, before figure-eighting .
Safe handling of man-made fibre ropes requires techniques which
differ from those for handling natural fibre ropes.
Man-made fibre ropes are relatively stronger than those of natural
fibre and so for any given breaking strain have appreciably smaller
circumferences, but wear or damage will diminish strength to a greater extent
than would the same amount of wear or damage on a natural fibre rope.
Polypropylene ropes
Polypropylene fibres make low-cost, all-purpose
ropes. They are light and float, making them suitable
as rescue or short mooring lines. However, the
ropes have a low resistance to abrasion and sunlight.
Polypropylene ropes
Polypropylene ropes come in a number of forms.They are probably the most popular of the man-made fibres at sea.The ropes
are cheap, light to handle, have the same strength whether wet or dry, and
they float.They are used extensively for mooring ropes and running rigging.
The melting point is low compared to nylon, 165°C. Friction-generated
heat should be avoided with this man-made fibre, which is extremely susceptible
to melting and fusing. Should the fibres fuse together, the rope is
permanently damaged and weakened.
It is resistant to chemical attack by acids, alkalis and oils, but solvents and
bleaching agents may cause deterioration. It neither absorbs nor retains
water, and because of this fact has recently been used for the inner core of
wire ropes,the advantage being that inner corrosion in the wire is eliminated.
However, the wire would still need to be lubricated externally.
Fibrefilm, a by-product from polypropylene, is a very cheap version of
the fibre. It is produced from continuous thin twisted polypropylene tape,
and used for general lashing purposes.
Ropes may be of a right-hand lay or left-hand lay, but the most common
is right-handed. It is essential to realise that each of the components
is turned (twisted) up in an opposite direction to that of its predecessor,
e.g. in right-hand lay, strands are laid up right-handed (clockwise), yarns
laid up left-handed, and fibres laid up right-handed.
Rope should be inspected internally and externally before use for
signs of deterioration, undue wear or damage.
Polyester ropes and hawsers
A heavy rope compared to the nylon and not as strong, but nevertheless
some of the polyester’s properties make it a worthwhile rope to have aboard.
It is considered to be more resistant to acids, oils and organic solvents than
its nylon counterpart, while its strength remains the same whether in a dry
or wet condition. It is used for mooring tails and mooring ropes.
Its disadvantages are very similar to nylon’s. It will not float. Splices must
have four full tucks and may draw more easily than with a natural fibre rope when under stress. It should not be surged on drum ends. Frictional
heat should be kept to a minimum when working about bitts or warping
drums.The melting point is between 230° and 250°C.
Ropes may be of a right-hand lay or left-hand lay, but the most common
is right-handed. It is essential to realise that each of the components
is turned (twisted) up in an opposite direction to that of its predecessor,
e.g. in right-hand lay, strands are laid up right-handed (clockwise), yarns
laid up left-handed, and fibres laid up right-handed.
Rope should be inspected internally and externally before use for
signs of deterioration, undue wear or damage.
Nylon ropes
This is the strongest of all the man-made fibre ropes. It has good elasticity,
stretching up to 30 per cent and returning to its original length. It is used
for such functions as shock-absorbing when coupled with a mooring
wire: the nylon forms a rope tail which takes the heavy shocks as a vessel
ranges on her moorings. It is also used in a combination tow line – one
section steel wire and one section nylon rope.
Nylon ropes are light to handle, twice as strong as an equivalent sized
manilla and give the appearance of a smooth slippery surface. They are
impervious to water, have a high melting point, 250°C, and in normal
temperature are pliable, being suitable for most forms of rigging.
The disadvantages of nylon ropes are that they do not float, and in cold
climates they tend to stiffen up and become difficult to handle. They
should not be left exposed to strong sunlight or be stowed on hot deck
surfaces, as their natural life will be impaired. The significant point with
these ropes is that they are used when great stress occurs. Should they part
under such stress, there is a tendency for them to act like elastic bands, an
extremely dangerous condition to be allowed to develop.The nylon rope
will give no audible warning when about to part; however, when under
excessive stress, the size of the rope will considerably reduce.They are difficult
to render on a set of bitts, and should never be allowed to surge.Any
splices in the nylon ropes will tend to draw more easily than in natural
fibre when under stress. Nylon is expensive, but its life may be considered
to be five times as long as its manilla equivalent.
Ropes may be of a right-hand lay or left-hand lay, but the most common
is right-handed. It is essential to realise that each of the components
is turned (twisted) up in an opposite direction to that of its predecessor,
e.g. in right-hand lay, strands are laid up right-handed (clockwise), yarns
laid up left-handed, and fibres laid up right-handed.
Rope should be inspected internally and externally before use for
signs of deterioration, undue wear or damage.
Rope splice guideline
The method of making eye splices in ropes of man-made fibres
should be chosen according to the material of the rope.
(i) Polyamide (nylon) and polyester fibre ropes need four full tucks in the
splice each with the completed strands of the rope followed by two
tapered tucks for which the strands are halved and quartered for one
tuck each respectively. The length of the splicing tail from the finished
splice should be equal to at least three rope diameters. The portions of
the splice containing the tucks with the reduced number of filaments
should be securely wrapped with adhesive tape or other suitable
material.
(ii) Polypropylene ropes should have at least three but not more than four
full tucks in the splice. The protruding spliced tails should be equal to
three rope diameters at least.
(iii) Polythene ropes should have four full tucks in the splice with protruding
tails of three rope diameters at least.
Mechanical fastenings should not be used in lieu of splices on man-
made fibre ropes because strands may be damaged during application of the
mechanical fastening and the grip of the fastenings may be much affected by
slight unavoidable fluctuations in the diameter of the strands.
Man-made fibre stoppers of like material (but not polyamide)
should be used on man-made fibre mooring lines, preferably using the `West
Country' method (double and reverse stoppering).
All Ropes should be inspected internally and externally before use for
signs of deterioration, undue wear or damage.
Ropes are made of short fibres that are spun into yarns,
which are then made into flat or twisted strands.
And the strands are spun or braided to make the finished
rope . More .....
Although natural fibre ropes are still widely used throughout the marine industry, they have been superseded by synthetic fibres for a great many
purposes. Not only do the majority of synthetic ropes have greater strength
than their natural fibre counterparts, but they are more easily obtainable
and at present considerably cheaper. More .....
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or flax fibres.The process of manufacture consists of twisting the fibres
into yarns and turning the yarns in an opposite direction to establish the
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