MSC 132Fishing 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 8Eight strand “square braid” is comprised of 8individual 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 waterA = weight (kg) in airDW = 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.

or16 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 +

or63.96 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 tochock is 2.5 times height (H).

H

Rope equals maximumdepth of water.

Heavy chain with swivel shackleup to 1.5 times depth of water.

Mushroom anchor orconcrete block.

Maximumdepth 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.