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.