Material Construction Features Deficiencies CommentsPolyester 3 strand High dry & wet
("Dacron") 8 strand strength
(·Terylene ") Double braid Moderate cost
Moderate Stretch
Nyton 3 strand High dry strength Low wet strength Wet slrenglh is
(Polyamide) 8 strand Moderate cost Low lahgue lile about 80% 01 dry
Doubte braid High stretch strength.
Polypropylene 3 slrand light weight Low strength Special medium
8 strand Low cost Low Mell Point strength poly·
Moderate stretch Creep propylene ropes
are available.
Polyethelene 3 slrand Light weight Low Strength Special medium
8 strand Low cost Low Mell Point strength poly·
Moderate stretch Creep ethylene ropes are
available.
Aramid Varied Very Low Stretch High Cost Old bend ratio
("Kelllar") High strength to Low abrasion similar to that of
weight ratio resistance wire. Tight bend
("Twarlon") radii do not allow
migration of load
and can cause
damage to the
fibres.
HMPE Varied High Beller flexibility
("Dyneema") strengthlweight characteristics Ihan
raUo Kell/ar, sometimes
used as a reptace-
ment for wire rope.
Nylon/Polyester! 6 strand High dry strength Low wet strength
Polypropylene Good fatigue life Hacklesr Jetkore") Good abrasion
resistance
Moderate cost
High stretch
Nylon Mono-& 6 strand High dry strength Low wet strength
Mutti-Filament 8 strand Good abrasion Low fatigue life
Fibre Mixture resistance
("Atlas Perlen") Moderate stretch
PoIyesterl 6 strand Moderate to high dry
Polypropylene 8 strand & wet strength
Fibre Mixture Moderate cost
(" Deltaftex ") Moderate stretch
Polyesterl 3 strand Moderate to high dry
Polvpropylene 8 strand & wet strength
Melt Mixture Moderaie cost
("Karat") Moderate stretchTABLE 6.1: SYNTHETIC ROPE CHARACTERISTICS6.3.1.2 Nylon
Dry nylon rope is sLightly slronner than polyester rope. However, moisture reduces the strength of
nylon fibre, and wet nylon rope has about the same st'rength as we! polyester. Wet nylon rope loses
slTength much faster under cyclic loading Ihan polyester. Thus a heavily used nylon rope will become
weaker than a heavily u cd poly er rope of the same size. For Ihis reason, if nylon is used for
tails, it should have at least 3 7°10 more strength than the associated wire rope. This rule is derived
from the geoeral 250;0 recommendation for tails plus an additional IO% allowance for rcduct.ion in
wet strength.Nyloo is more elaStic than a.ny other material. When broken in it will stretch 12 .% or more at
501176 MBL. This characteristic makes it especially suitable for use as tails with wire hawsers where
elasriciry is required, such as for STS operations and at berths subject to wave motion or surge .. It is
less suited to operations where rigid moorings are required, such as a large ship in a loading arm
envelope at a poor weather ben h.