MSC 132 Fishing Gear Technology I

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MSC 132Fishing Gear Technology I
Ropes and Fibers

• With Excerpts from
• Fishermans Workbook
• compiled by J. Prado, Fishing News Books,
  Oxford1990
• Yale Cordage Ropes For Industry
• 2nd. Edition,Yale Cordage Inc., Yarmouth,
  ME.1985

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Constructions Each type of line has its special
characteristics therefore, by knowing the type
of material and the method of manufacture, you
can decide on the particular rope for your
desired use.
Double Braid This is really two separate ropes in
one. The core, which is a single braid, is over
braided with a second sleeve. This construction
allows maximum flexibility options to utilize the
same or dissimilar fibers. This construction
entirely shields one of the two rope elements
from abrasion. It is a spliceable rope.
Single Braid This construction leaves a void in
the center and utilizes strand counts of 8, 12,
or 16. The hollow is instrumental in the easy
splice procedure. Hollow braids are
non-rotational and are an efficient way to
utilize fiber. It is a spliceable rope.
3-Strand The original rope construction is the
simplest type of rope. It is formed by twisting
fiber into a strand. Three formed strands are
then twisted to produce the finished rope. It is
a spliceable rope.
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Constructions Always consult the manufacturer
before using rope when personal safety or
possible damage to property is involved. Make
sure the rope is adequate for the job. Do not use
too small a rope or the wrong type.
Parallel Core This construction consists of a
core of parallel yarns that are held together by
a wide variety of different means from extrusion
to braiding. Due to its low twist level, these
ropes are usually very strong but have limited
applications due to loss of strength in bending
and termination constraints.
Solid Braid This rope is also called Sash Braid
Rope. Solid braid ropes are constructed of
various bundles of fiber interlocked together in
a circular braiding pattern. They are not
spliceable.
Plaited Rope 8 Eight strand square braid is
comprised of 8 individual strands which are
woven together as 4 pairs. Its strength is
virtually identical to 3 strand with its major
advantage being its non-rotating characteristics.
Diamond Braid ropes are constructed from various
bundles of fiber braided in a herringbone pattern
to form a jacket over a parallel fiber center
core. These are also referred to as mayploe
braids and are not spliceable.
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Material Once a rope construction is selected
for a particular use, you must decide on the kind
of material or fiber.
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Material Most manufacturers provide
specification sheets and/or generalized fiber
selection tables. Tables are also available in a
variety of reference books.
Manufacturers Examples
Class Handout
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Manufacturers Selection GuideRhino Ropes,
Wellington Commercial Products General Catalog
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Class Handout Selection Guide
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Material Identification You may encounter a
pre-existing rope and/or fiber that you cannot
identify. Guides and specific testing indicators
may help with your assessment.
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Strength and Size Selection
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Class Handout Selection Guide
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Class Handout Selection Guide
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General Rope Usage
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Sinking Materials
Floating Materials
Multiplication factor used to calculate the
weight in water of different materials.
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P A x 1 DW/DM Where P weight (kg) in
water A weight (kg) in air DW density (g/cc)
of water (freshwater 1.00 sea water 1.026) DM
density (g/cc) of material
The term in brackets, the multiplication factor,
has been calculated for the materials most
commonly used in fisheries, with the results
given in the Density of Materials table. The
factor followed by a sign indicates a sinking
force. The factor followed by a sign indicates
a buoyant or floating force. To obtain the weight
in water of a certain quantity of material,
simply multiply its weight in air by the factor.
The same multiplication factor can be used with
either the metric or the customary system of
measurement.
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Calculation Examples Air Weight and Weight
in Water

• Fiber Cordage Typical Weights
• Nylon (PA) ½ O , 1½ circ.
• Net Weight per 100 6.6 lbs.
• Feet per Pound 15
• Breaking Strength 6,650 lbs.
• 60 feet of this rope weighs?
• Air Weight

3.96 lbs. (4 lbs.)
6.6 lbs. 100 ft. .066 lbs. per foot of
rope. .066 lbs. x 60 ft. 3.96 lbs. or 16
ounces (1 lb.) 15 feet 1.0666 ounces per
foot (1.07 oz.) 60 feet x 1.066 oz. 63.96
ounces 16 oz. 3.998 lbs. (4.01 lbs.)
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Calculation Examples Air Weight and Weight
in Water

• Fiber Cordage Typical Weights
• Nylon (PA) ½ O , 1½ circ.
• Net Weight per 100 6.6 lbs.
• Feet per Pound 15
• Breaking Strength 6,650 lbs.
• 60 feet of this rope weighs?
• Air Weight 3.96 lbs. (4 lbs.)
• Water Weight (salt water)

6.336 oz.
3.96 lbs. x .10 .396 lbs. .396 lbs. x 16 oz.
6.336 ounces or 63.96 ounces x .10
6.396 ounces
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Rigging a Mooring
Length of pennant to chock is 2.5 times height
(H).
H
Buoy
Mooring Buoy
Rope equals maximum depth of water.
Maximum depth of water
A typical mooring buoy is designed to transmit
the strain through a solid rod. Buoys perform a
useful function in removing much of the vertical
load which allows the boats bow more freedom to
lift to heavy seas.
Heavy chain with swivel shackle up to 1.5 times
depth of water.
Mushroom anchor or concrete block.
Mooring Permanent ground tackle a place where
vessels (or scientific equipment) are kept at
anchor. Illustrations and Definition from
Chapman/Piloting Seamanship Small Boat
Handling, 61st. Edition, Hearst Marine Books, New
York, NY 1994
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Rigging a Mooring Calculation Example
What type of rope should you use?

• Most texts and manufacturers would recommend
• A three-strand twisted nylon rope with a medium
  lay.
• Excellent strength to weight ratio.
• High stretch and elasticity.
• Excellent abrasion resistance.
• Size Depends on normal working loads and/or
  dynamic loading.

How much rope will I need?

• Depends on the maximum depth of the water!
• For the purpose of this example and the ensuing
  calculations lets assume our maximum depth of
  our water is 32 Feet.
• In addition, lets assume we will be mooring a
  motorboat approximately 25 feet in length.

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