Ship Peter and Paul. V. Dygalo, M. Averyanov. History of the ship. Sailing and rowing frigate "Apostle Peter"
Cables are products twisted from steel wires or twisted from plant and synthetic fibers.
On ships, cables are used as running and standing rigging, hoists, moorings and tugs, slings, nets, throwing ends, etc. Mats, fenders, mops, etc. are made from old cables. Each ship is equipped with cables depending on its size and appointments. Currently, plant ropes have been practically replaced by synthetic ones.
The characteristics of the cable that determine its performance are strength, flexibility, elasticity, weight and resistance to external factors - water, temperature, solar radiation, chemical substances, microorganisms, etc. Knowledge of these characteristics allows us to ensure proper care of the ropes, their correct storage and use on the ship.
The strength of a cable characterizes its ability to withstand tensile loads. There are breaking and working strengths of the cable. The breaking strength of a cable is determined by the lowest load at which it begins to break. This load is called breaking force. The working strength of a cable is determined by the maximum load under which it can operate in specific conditions. long time without damaging the integrity of individual elements and the entire cable. This load is called the permissible force. Its value is set with a certain margin of safety. It is usually accepted that the working strength of a cable is 3 times less than its breaking strength.
The thickness of the cable is measured in millimeters: vegetable and synthetic along the circumference, and steel - along the diameter. The thinner the cable, the easier and more convenient it is to work with.
The flexibility of a cable characterizes its ability to bend without breaking the structure or losing strength. The greater flexibility of the cable ensures convenience and safety of working with it.
Elasticity (elasticity) of a cable is its ability to lengthen under tensile load and return to its original dimensions without residual deformation after its removal. The elasticity of the cable is a relative quality. For example, a cable with high elastic properties is convenient for the manufacture of towing cables, but it will poorly fix the position of the vessel at the berth if mooring lines are made from it, and is unsuitable for standing rigging.
The weight of the cable determines the complexity of working with it. The stronger and lighter it is, the more convenient it is to work with.
Plant ropes are made from specially processed, strong, long fibers of certain plants (hemp, agave, spinning banana, cotton, etc.). According to the laying method, they are divided into cable and cable work ropes (Fig. 5.1).
Rice. 5.1. Plant ropes:
a) - cable work; b) - cable work:
1 - threads, 2 - heels, 3 - strands, 4 - strands
The production of any plant cable begins with the fibers being twisted into threads called heels. A strand is twisted from several heels, and several strands twisted together form a wire rope. Depending on the number of strands, cables can be three-, four-, or multi-strand. A cable with fewer strands is always stronger than a cable of the same thickness, twisted from a larger number of strands, but is inferior in flexibility. A cable cable is obtained by twisting together several cable cables, which in the structure of such a cable are called strands. Cable work cable is inferior in strength to cable work cable of the same thickness, but it is more flexible and elastic. To prevent the cable from unwinding and maintain its shape, the lay of each subsequent element of the cable structure is done in the direction opposite to the lay of the previous element.
On naval vessels, hemp, manila and sisal cables are most commonly used.
Hemp cables are made from hemp fibers - hemp. Significant disadvantages of hemp cables are susceptibility to rotting and high hygroscopicity. To protect the cable from rotting, its strands are twisted from heels coated with tree resin. Such cables are called resinous cables.
Manila cables are made from spinning banana fibers. Of all plant ropes, they have the best performance characteristics. The cables have great strength, flexibility and elasticity: under a load equal to half the breaking force, they elongate by 15–17% without loss of strength. Cables get wet slowly and therefore do not sink in water for a long time, do not lose elasticity and flexibility when exposed to moisture, dry quickly, and are little susceptible to rotting. The cables range in color from light yellow to golden brown.
Sisal ropes are made from fibers from the leaves of the agave plant, a tropical plant. They have approximately the same elasticity as manila cables, but are inferior in strength, flexibility and moisture resistance. Wet sisal cables become brittle and have a light yellow color.
Depending on the manufacturing method and thickness, plant cables have special names: lines - cable-made cables up to 25 mm thick and cable-made cables up to 35 mm thick; perlines – cable work cables with a thickness of 101 to 150 mm; ropes – cable work ropes with a thickness of more than 350 mm.
High-strength lines are woven from several spools of high-quality hemp. A tench made from low-grade hemp is called shkimushgar. It is used to make mats, fenders and other products. Lines obtained by weaving linen threads are called cords. Braided cords are flexible and elastic. They perceive torsional forces without large external changes and deformations. Thanks to these qualities, cords are used for making lanyards and signal halyards.
Steel cables are made from galvanized steel wire with a diameter of 0.2 to 5 millimeters. By design, steel cables are divided into three types: single, double and triple lay (Fig. 5.2).
Rice. 5.2. Steel cables:
1 – single; 2 – double; 3 – triple lay
Single lay cables, called spiral cables, consist of a single strand in which the wires are twisted in a spiral in one or more rows and have great flexibility. They are used in various devices and mechanisms, for applying benzels and during various rigging works.
Double lay cables are made by laying several strands around one common core, which can be vegetable or metal. Double lay cables are called wire rope cables.
The core fills the void in the center of the cable and prevents the strands from falling toward the center. The following cores are used: steel wire, oiled hemp and other vegetable cables, synthetic and asbestos materials. The core ensures the density of the cable and maintains its shape when bending under high stress. Organic oiled cores protect the internal wires from rusting and, like synthetic cores, make the cable softer and more flexible. In addition to the central core, many cables have an organic core inside each strand.
To obtain a triple lay cable, several double lay cables are twisted together, which in this case are called strands. Triple lay cables are called cable cables. Such cables are made of thinner wire, they are much more flexible, but at the same time weaker than cable cables by about 25%. Mainly used in light lifting mechanisms with rope winding on drums, for boat hoists, etc. Thick cables with a diameter of 40 - 65 mm are used for mooring lines and tugs.
Steel cables are available in any length, but not less than 200 meters. The thickness of a steel cable is determined by its diameter. Steel cables are produced wound on wooden or metal spools. Each coil (spool) of cable must be equipped with a tag and a certificate indicating the name of the cable, its length, thickness and tensile strength, net weight (weight 100 m) and packaged weight (with spool), date of manufacture. In addition, the design of the cable and the characteristics of the wire from which the cable is made are indicated. Upon acceptance, a thorough inspection should be carried out with control measurements of thickness in several places. There should be no flattened strands, torn or broken wires. The galvanized wires must not be damaged or cracked.
During operation, the cables must be lubricated at least once every three months. Cables stored on the ship are lubricated at least once a year.
With proper care, the service life of standing rigging cables is virtually unlimited. For running rigging cables it is 2–4 years.
Synthetic cables are made from polymer materials. Depending on the brand of polymer, they are divided into polyamide, polyester and polypropylene. Polyamide includes cables made from fibers of nylon, nylon (nylon), perlon, silon, and other polymer materials.
Polyester cables are made from fibers of lavsan, lanon, dacron, dolen, terylene, and other polymers. The materials for the manufacture of polypropylene cables are films or monofilaments of polypropylene, tiptolen, boustron, ulstron, etc.
Rice. 5.3. Synthetic cables
In terms of physical and mechanical properties, synthetic cables have great advantages over vegetable ones. They are lighter than the latter and significantly superior in strength. For example, the tensile strength of an ordinary nylon cable with a thickness of 90 mm is 2.5 times higher than the tensile strength of a Manila cable of the same thickness and more than 3 times higher than that of sisal and resin hemp.
Synthetic cables are flexible and elastic, moisture-resistant and, for the most part, do not lose strength when wet and when air temperature changes, which allows them to be used when the vessel operates in various climatic conditions. The cables are resistant to solvents (gasoline, alcohol, acetone, turpentine) and are not susceptible to rotting or mold.
Synthetic cables have disadvantages and features that must be taken into account when using them. Polyamide cables are damaged when exposed to solar radiation, acids, drying oil, fuel oil, etc. Polyester cables are destroyed by contact with concentrated acids and alkalis. The tensile strength of polypropylene cables decreases at temperatures above +200, and at negative temperatures, flexibility also decreases. All synthetic cables, when rubbing against the surface of equipment parts, as well as as a result of friction of strands and fibers among themselves inside the cable, are capable of accumulating a charge of static electricity, which, when discharged, causes sparking, which is dangerous in terms of fire. The outer fibers are not sufficiently resistant to abrasion and can melt, especially when rubbing against rough surfaces. Synthetic cables have great elasticity, which creates a danger for people if it breaks.
All synthetic cables, like vegetable ones, lose strength when exposed to sunlight and quickly “age”, so they should be stored indoors or under covers for a long time, and dried in the shade.
Contaminated synthetic cables must be washed with salty sea water. They also need to be periodically subjected to antistatic treatment - soaking for 24 hours in sea or simply salt water. Dousing the cable with seawater will also contribute to the same goals.
Steel rope - rope structures can contain one or many strands (Table 5.1), (Fig. 5.1). Strands consist of wires that are divided into equally normal cross-section structure (all wires with the same cross-section) and different diameters (combined cross-section structure). The breaking force of a rope mainly depends on its diameter. With the same diameters, the rope with a large number wire is more flexible.
Rice. 5.1 Double lay steel rope
1 - wire; 2 - strand; 3 - core
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The ropes vary in design
Single lay (spiral)- consisting of one, two or three layers of wire twisted into concentric spirals (Fig. 5.2)
Rice. 5.2 Single lay (spiral)
Double lay - consisting of six or more strands twisted into one concentric layer (Fig. 5.3).
Fig.5.3 Double lay
Triple lay - consisting of strands twisted in a spiral into one concentric layer (Fig. 5.4).
Rice. 5.4 Triple lay
According to the type of contact of the wires between the layers, ropes are distinguished:
With point touch (type TK)- lays of wires have different steps along the layers of the strand, and the wires cross between layers. This arrangement of elements increases their wear during shear during operation, creates significant contact stresses that contribute to the development of fatigue cracks in the wires, and reduces the coefficient of filling of the rope section with metal.
With linear touch (LK type)- such strands are produced in one technological step, while the constancy of the wire laying pitch in all layers of the strand is maintained. To obtain a linear touch, the diameters of the wire and strand are selected depending on the design of the latter. So, in top layer strands of rope type LK-0 use wires of the same diameter in layers, strands of type LK-R have wires of different diameters in the outer layer, and strands of type /7/S-Z use wires that fill the space between wires of different diameters. There is a type of rope with a linear touch of the wire between the layers and having layers in the strands with wires of both different and identical diameters - LK-RO. In three-layer linear touch strands, there are various combinations of the above types of strands. It should be noted that the performance of ropes with linear contact of wires in strands, with the correct choice of rope design, is much higher than the performance of ropes with point contact of wires.
With point-linear touch (TLK type)- strands of point-linear touch are obtained by replacing the central wire in strands of linear touch with a seven-wire strand: in this case, a layer of wires of the same diameter with a point touch is laid on a two-layer strand of the LK type. The design of these strands makes it possible to produce them on spinning machines with a relatively small number of bobbins. In addition, TLC strands, with appropriate selection of laying parameters, have increased non-twisting properties;
Based on the core material, ropes are distinguished:
With organic core (OC). Most rope designs use lubricated organic cores of hemp, manila, sisal or cotton yarn as the core at the center of the rope, and sometimes at the center of the strands, to provide the required flexibility and resilience. The use of cores made of asbestos cord and artificial materials (polyethylene, nylon, nylon, etc.) is also allowed.
Metal Core (MC). It is advisable to use a metal core in cases where it is necessary to increase the structural strength of the rope when multilayer winding it on a drum, to reduce the structural elongation of the rope during tension, and also when operating the rope under conditions of elevated temperature. One of the most common designs of this type is a double lay rope made of 6-7 wire strands located around a central seven-wire strand. The metal core can be made of ordinary rope or soft wire with a tensile strength of no more than 900 N/mm2.
According to the combination of laying directions of strands and rope:
Rope single-sided lay- with the same direction of lay of the wires in the strands and the strands in the rope (Fig. 5.5).
Rice. 5.5 Single lay rope
Rope cross lay- with the opposite direction of lay of strands and rope (Fig. 5.6).
Externally, a cross lay rope differs in that the wires on its surface are located parallel to the axis of the rope. The wires of a one-way laid rope are located at an angle to its axis.
One-way laid ropes are less rigid, but are prone to unwinding. In crane mechanisms, as well as for the manufacture of slings, they are used.
cross lay nuts, more rigid, but not prone to unwinding under load. Non-unwinding ropes twisted from pre-deformed wires, which will be described below.
According to the laying method, ropes are divided:
Unwinding- the wires are not freed from internal stresses arising during the process of laying wires into strands and strands into a rope. Strands, strands and wires in this case do not retain their position in the rope after removing the bandages from its ends;
Non-unwinding (N)- when laying wires into a strand and strands into a rope, internal stresses are relieved by straightening and preliminary deformation in such a way that after removing the dressings from the end of the rope, the strands and wires retain the given position. Non-unwinding ropes have a number of advantages compared to unwinding ones: somewhat greater flexibility and a more uniform distribution of tensile forces on the strands and wires, increased resistance to fatigue stress, and no tendency to disrupt straightness when unfolding.
According to the degree of twist, ropes are divided:
Rotating;
Low-rotating (MK). These ropes should be distinguished from non-unwinding ones. In low-twist ropes, thanks to the selection of laying directions of individual layers of wires (in spiral ropes) or strands (in multi-layer double lay ropes), rotation of the rope around its axis is eliminated when the load is freely suspended. A low-twist rope can be made either non-unwinding or unwinding. Required condition The manufacture of low-twisting ropes is the arrangement of strands in two or three concentric layers with the opposite direction of lay of each concentric row of strands. In this case, the rotational moments of all strands of the rope are balanced, which prevents the overall rotation of the rope around its axis.
General information. Marine vessels use vegetable, steel, composite and synthetic cables. The main operational characteristics of cables are their strength (breaking and working), elasticity, flexibility and weight, as well as resistance to external factors - water, microorganisms, chemicals, sun, etc.
The breaking strength of the cable R (kgf) is determined by the minimum tensile force at which the cable begins to collapse (tear). Under ship conditions, this strength can be calculated using the empirical formula
where k is the strength coefficient (Table 1);
C – cable circumference, mm.
The working strength of a cable is the maximum load at which the cable is capable of operating in specific conditions for a long time. In practice, the working strength of the cable is assumed to be equal, depending on the operating conditions and purpose of the cable, from 1/6 to 1/10, and for lifting machines(steel cable) – up to 1/20 tensile strength.
Elasticity, or elasticity cable is its ability to elongate under load and return to its original state without residual deformation after removing the load. Elasticity is maintained in the cables under relatively small loads compared to its breaking strength. Under significant loads, even after they are removed, the cables retain a certain elongation - permanent deformation, which reduces the strength of the cable. In this regard, the maximum working load is set for the cable, in most cases not exceeding 1/6 of the breaking strength.
Plant ropes (Fig. 1) are made from fibers of stems, leaves or bark. Vegetable ropes are used on naval vessels - hemp (from hemp fiber), manila (from fiber of a spinning banana), sisal (from fiber from agave leaves).
Rice. 1. Structure of plant ropes:
1 – heel; 2 – strand; 3 – wire rope work; 4 – cable work cable; 5 – three-strand cable; 6 – four-strand cable with a core; 7 – strand; 8 – fibers
To make a cable, fibers are twisted into threads (clockwise - from left to right), called heels. Several heels are twisted into a strand (from right to left). By twisting three or more strands together (from left to right), you get the so-called direct descent cable; The cable for the reverse descent operation is twisted in the reverse order. If you twist several wire ropes together (each of which in this case is called a strand), you get a cable rope whose strength is 25% lower than a wire rope of the same thickness, but it is more elastic and dries better.
In technical terminology, cable-type cables are called ordinary, and cable-type cables are called turn-up cables.
The thickness of plant cables is measured along their circumference in millimeters. Cable ropes from 100 to 150 mm are called ropes, from 150 to 350 mm are called cables, and over 350 mm are called ropes.
Plant cables with a circumference of 25 mm or less are called lines. Strands in a line are usually called threads. A two-strand tench made from low-grade beard hemp is called shimushkar; it is used for weaving mats and other rigging work. To the lines special purpose include linen and braided cords, from which lotlini, laglini, signal halyards, etc. are made.
Hemp cables made from non-tarred hemp heels are called bleached, and those made from tarred hemp are called tarred. Tarring the cable is done to protect it from rotting.
Hemp cables of cable work (ordinary) are made bleached and resinized, and hemp cables of cable work (lapel) are made only of resin. Resinized cable is approximately 5% weaker than white cable, and its weight is 11-18% greater; its service life is longer than white. When loaded, hemp cables can elongate by 8-10% without compromising their strength. It is recommended to use hemp ropes for the manufacture of running rigging for boats, handrails, and slings. Resined wire ropes are used as mooring lines and also for making cargo nets.
Manila cables are usually produced in white; at a load equal to half the breaking load, these cables can elongate by 15-17%. They get wet more slowly and therefore do not sink in water for a long time, without losing elasticity and flexibility under moisture pressure. Manila cables are used for running rigging, mooring lines, cargo pendants, tugs, and throwing lines.
Sisal cables are usually also produced in white. In terms of strength, they are inferior to hemp and manila. Under breaking load, their relative elongation is about 20%. Such a cable floats in water, but easily absorbs it. Sisal cables are used to make handrails, mooring lines, guy ropes, etc.
The approximate service life of a plant cable for cable work is three years, for perlines – two years, for other cables – about one year.
Steel cables used on naval vessels are made of carbon, galvanized or non-galvanized wire with a thickness of 0.4 to 3.0 mm.
Steel cables consist of strands that are formed by laying wires in one or more rows around one central wire or around an oiled hemp core, which protects the strand from rust and provides it with greater flexibility. Steel cables, depending on the number of strands in them, are single, double and triple lay. Single lay cables consist of one strand; double lay - like plant cables, cable work consists of several strands, most often six, twisted around one common core (plant or metal); triple lay - from several double lay cables twisted together.
Depending on the thickness of the wire and the nature of the lay, steel cables can be rigid or flexible.
Rigid cable is made from thick wires without a core or with one organic core; it is the strongest of steel cables; it is used for standing rigging.
Flexible cable is elastic, it is made of thin wires; each strand has a core of plant fibers; used for running rigging, mooring lines, tugs, trawls, lifting devices.
The thickness of a steel cable is determined by its diameter. At the customer's request, steel cables can be produced in coils of any length; the usual length of a steel cable coil is 250, 500, 750 m. The relative elongation of steel cables is small, no more than 3%.
The advantage of steel cables over vegetable cables is that they are lighter and thinner, but they deteriorate faster from sharp bends and are less flexible.
Combined cables made from wire strands covered with hemp yarn. These include “Hercules” type cables, which are used as mooring lines and tugs.
Synthetic cables are woven from threads of various artificial fibers: nylon, nylon, lavsan, polypropylene, etc. In their own way appearance and their designs resemble plant ones. IN Lately Polypropylene braided cables began to be used. Synthetic cables are lighter, more elastic and 2 - 2.5 times stronger than hemp cables of the same thickness; In addition, they are not subject to rotting or corrosion. The disadvantages of synthetic cables include the fact that when broken, they, like rubber, contract with great strength, fly back and create a great danger for people working with them; When friction occurs, synthetic cables are capable of accumulating a charge of static electricity, which, when discharged, sparking can lead to damage to the cable, as well as a fire.
Synthetic cables are used for navy as tugs, moorings and other cases where their high elasticity can be used. Comparative data for steel, hemp and nylon cables are given in table. 2.
Rigging chains are chains intended for ship rigging. Their links are made without buttresses from round iron, the diameter of which determines the size of the chain. There are short-link and long-link rigging chains; the latter are used, as a rule, for stoppers on arrow toppers.
A rigging chain is approximately three times stronger than a steel cable of the same diameter and eight times stronger than a hemp cable. Its disadvantages include large mass and low elasticity when tensioned, as well as the risk of rupture at low air temperatures. The magnitude of the working force P (kgf) allowed on the rigging chain can be approximately determined by the formula:
where d is the diameter of round iron, mm.
A chain whose crown wear has reached 10% or more of the original diameter is considered unusable.
Marine rope is a very general designation for all kinds of “rope products” used in shipping. Their general qualities are increased breaking load, increased wear resistance, low hygroscopicity, resistance to environment. Depending on the thickness, manufacturing method (twisted, braided, with or without a core), as well as on the purpose, ship ropes are called cables, handrails, cords, “ends” (this is maritime jargon). In the days of the sailing fleet, ropes were widely used in rigging; without them it was generally impossible to create sailing equipment. Nowadays, sailing yachts also require rigging. However, on modern ships, ropes are used quite widely, for example, mooring and towing ropes.
In the days of sailing ships, sea rope was made from natural materials, sesal, manila, and hemp. Manila ropes were especially valued. They are stronger than hemp (made from hemp), do not rot, and are more flexible and elastic. Hemp ropes are more susceptible to rotting and absorb water well. But in most cases, plant ropes were tarred (at that time they were called tarred, non-tarred - bleached). This was done to protect the fibers from exposure to salty sea water, but as a result of tarring they became less durable and much heavier. Therefore, winches and other lifting mechanisms were used to tighten the rope.
Nowadays, marine rope is mainly a product of the chemical industry; they are made from synthetic fibers.
The main types of polymer fibers for making ropes are polyamide (nylon, perlon, nylon, silone) and polypropylene (tiptolen, bustron, ulstron).
Synthetic ropes have many advantages over vegetable ones. They are stronger, more elastic, lighter in weight, moisture resistant, do not rot, and do not lose their qualities when exposed to sea water. They are also resistant to various solvents (gasoline, alcohol, acetone, turpentine). Polyamide fibers can only be destroyed with concentrated sulfuric acid. In addition, and importantly, they retain their properties over a fairly wide temperature range. Approximately from -40 to + 60. But ships have to sail in a wide variety of climatic conditions, both in tropical seas and in northern ice.
When a ship approaches a pier, it must be secured somehow. The rope with which a sea vessel is tied is called a mooring rope. And sailors call mooring to a pier mooring. When mooring, the mooring line is secured around the bollard. An expression often found in novels about the sea: “to give up the mooring lines” means that the mooring rope is removed from the bollard. Other towing and mooring devices are also used. But for small vessels, the use of ropes is still very important today. What kind of rope should be used to tie a sea vessel, or a mooring rope for small vessels? The length of such a rope is usually 20-30 meters, and the thickness depends on the displacement of the vessel. If we translate this term into land concepts, then from the weight of the vessel.
Mooring ropes are made from natural or synthetic fibers.
Synthetic ropes are by definition stronger. So, for a vessel with a displacement of 200-300 kg, a synthetic rope with a diameter of 4-5 mm is sufficient. If the rope is made of plant fibers, then its thickness should be 2-3 times greater.