Ropes and Fibers - cfcc.educfcc.edu/blogs/srowe/files/2015/07/Ropes-Fibers.pdf · MSC 132 Fishing...
Transcript of Ropes and Fibers - cfcc.educfcc.edu/blogs/srowe/files/2015/07/Ropes-Fibers.pdf · MSC 132 Fishing...
MSC 132
Fishing Gear Technology I
With Excerpts from:
Fisherman’s Workbookcompiled by J. Prado, Fishing News Books, Oxford:1990
Yale Cordage Ropes For Industry2nd. Edition,Yale Cordage Inc., Yarmouth, ME.:1985
Ropes and Fibers
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.
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.
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.
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.
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.
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.
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.
Material: Once a rope construction is selected for a
particular use, you must decide on the kind of material or “fiber”.
Material: Most manufacturers provide specification
sheets and/or generalized fiber selection tables. Tables are
also available in a variety of reference books.
*Class HandoutManufacturers Examples
Manufacturers Selection Guide**Rhino Ropes, Wellington Commercial Products General Catalog
Class Handout – Selection Guide
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.
Strength and Size Selection
Class Handout – Selection Guide
Class Handout – Selection Guide
General Rope Usage
*Multiplication factor used to calculate the
“weight in water” of different materials.
Sinking Materials
Floating Materials
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.
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 =
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.)
3.96 lbs. (4 lbs.)
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) =
3.96 lbs. x .10+ = .396 lbs.+
.396 lbs. x 16 oz. = 6.336 ounces +
or
63.96 ounces x .10+ = 6.396 ounces +
+6.336 oz.
“Rigging a Mooring”
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
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 boat’s bow more
freedom to lift to heavy seas.
Mooring Buoy
Buoy
Length of pennant to
chock is 2.5 times height (H).H
Rope equals maximum
depth of water.
Heavy chain with swivel shackle
up to 1.5 times depth of water.
Mushroom anchor or
concrete block.
Maximum
depth of water
“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 let’s
assume our maximum depth of our water is 32 Feet.
• In addition, let’s assume we will be mooring a motorboat
approximately 25 feet in length.