Anchor chain - an important element of the anchor device and the entire ship as a whole. The first anchor chains appeared two hundred years ago. Now the design of the anchor chain complies with standards and is undergoing mechanical tests.
Anchor Chain History
For centuries, sailors have used hemp ropes for anchoring. Sailing vessels of the middle of the last millennium were held during anchorage by small anchors, and the strength of the hemp ropes was sufficient. With the development of shipbuilding, marine ships and, therefore, anchors became heavier. In order to have enough strength, hemp ropes reached half a meter in circumference, so it was necessary to use thinner ends to wind the ropes into a bollard or to enclose the spire drum. In addition, hemp ropes were rubbed against the anchor claw and cut off with ice to compensate for their low weight, the anchor stock had to be heavier.
The end of the eighteenth and the beginning of the nineteenth centuries are known for isolated cases of the use of metal anchor chains, which proved to be remarkable both during storms and during ice drift on the Thames. The official start of the use of the metal chain is considered to be 1814.
The frigate "Pallas", launched in 1832, is the first ship of the Russian fleet equipped with anchor chains.
Already in 1859, before being installed on the ships of the British Navy, anchor chains began to be tensile tested in accordance with the requirements developed by the Lloyd's Register, and in 1879 - even for breaking.
Shipping Register Requirements
The Russian fleet began to develop especially rapidly in the early twentieth century, and the classification of ships that existed at that time ceased to meet safety requirements. Therefore, in 1913 the Russian Classification National Classification Society was formed, which in Soviet history became known as the USSR Register, and now the Russian Maritime Register of Shipping (RS). Its tasks include the measurement and classification of ships and floating structures, maintaining their registers, monitoring them and technical supervision.
According to the requirements of the Register, seagoing vessels must have two operational ships and one spare sea anchor. At the same time, the length of each chain should be at least two hundred meters, a spare anchor bow is provided. As well as two connecting links and an end bracket. The anchor device of the ship provides mechanisms whose power allows you to choose anchors in no more than half an hour. The components of the anchor device are subject to supervision by the Register.
Anchor device
An anchor attached to the chain is given or raised using special mechanisms and devices. Anchors, chains, stoppers, devices for recoil of the root end of the chain, closures - all this together makes up the ship's anchor device. It with two anchors on the sides is located in the bow of the vessel. An electric or hydraulic winch is also installed on the nose. The main part of the winch is an asterisk on which chain links are wound. The winch design also includes drums on which mooring lines are wound.
The chain from the anchor passes through the recess in the board, the anchor claw and the stopper, wraps around the winch sprocket and the free end fastens with a bracket to the vessel in the chain box.
On some ships, feed anchor devices are installed. As space is limited at the stern, a spire is used to raise one or two stern anchors. This is a rotating drum with an asterisk at the bottom, mounted vertically. It is driven by an electric motor, which can be located either in the drum itself or under the deck. A chain is wound around an asterisk. The photo shows the device of the spire, where 1 is the drum, 2 is the horizontal sprocket, 3 is the anchor chain.
Locking and fastening elements
The stoppers attach, prevent spontaneous etching and hold the chain and anchor in the clutch in a taut position. They can be stationary or portable: chain and deck.
By design, the stoppers are screw cam or with a mortgage link. Eccentric stoppers are installed on small vessels. Chain stoppers are short bows that pass through the anchor bracket and are attached to the butt ends on the deck with two ends.
Anchor anchors, which are used to clean the anchor and anchor chain, can be ordinary, welded or cast for transport and fishing vessels; open in the form of a massive casting with a gutter on low-sided vessels; with a niche in the side lining on passenger ships, ice-going vessels, which allow to anchor flush with the lining, thereby reducing the risk of damage to it.
Types and design of anchors
Today, there are four types of anchors. With the help of the anchor anchors, which are located in the bow, the vessel is held in place. Their maximum weight on aircraft carriers reaches 30 tons. Auxiliary anchors in the stern are designed to prevent the ship from turning around the ship’s center. For long-term retention, floating objects, such as buoys or lighthouses, are fixed with “dead” anchors. Deliveries hold special purpose ships, the so-called technical fleet vessels for mining.
Today in the world more than five thousand species of anchors are known. But the sea anchor consists of four main parts. The basis of the entire structure is the spindle. Horns with paws that are buried in the ground and hold the ship in place are fixed on the spindle motionlessly or on a hinge. Perpendicular to the horns and spindle, there is a rod that turns the anchor at the bottom after immersion and prevents the horns from lying horizontally. The anchor to the rope or anchor chain is secured by a bracket and a ring called the eye.
The main elements of the anchor chain
The main element of the anchor chain is the link, which is made of a steel bar welded by forging with cast-iron buttress or cast together with a spacer made of mild rolled steel.
The anchor chain bows are connected by connecting brackets, simple or patented, the most common of which is the Canter bracket. Simple staples are not immune to spontaneous opening. In addition, when using them, the end links of the bows are made without buttresses and are larger than ordinary links.
Kenter's bracket is similar to a usual link, only detachable. Two halves of the bracket are connected to the lock and held by a spacer, into which a stud with a lead stopper is inserted at an angle.
The swivel, which protects the anchor chain from twisting while anchoring, as a rule, is a structure of the swivel itself, the end link and two reinforced links between them.
Reinforced link - with buttress, smaller in size than the end link, but larger than the usual link. The anchor bracket is brought into the eye of the spindle of the anchor, it also connects to the end link of the swivel with an anchor bracket, the back turned to it.
Anchor chain design
An anchor chain, like any one, consists of links, but the design is not so simple. The links are assembled into segments of a certain length, which are called intermediate bows. According to the standards of the Russian fleet, the length of the bow is 25 meters, in the British, where the measurement of length in yards is accepted - 27.43 meters or 30 yards. Bows to the desired length of the chain are collected and interconnected by links of Canter. This assembly method makes it easy to remove damaged areas and change, if necessary, the length of the anchor chain.
The root bow, which is fixed in a chain box, ends on the one hand with an end bracket, and on the other hand it is reinforced with gvacogals. The jacquard bow is a short chain attached at one end and with a hook at the other end. The photo shows that you can release the tip of the hinge hook. This design allows one person to quickly free the ship from the anchor chain.
Anchor bow (running end) also differs in construction from intermediate ones. It includes a swivel. And the bow ends with a bracket to which the anchor is attached.
Anchor Chain Dimensions
The main size that determines the thickness and characteristics of a chain is its caliber. Gauge - the diameter of the bar from which the link is made, or the end section of the link, depending on the method of its manufacture. Through the caliber, other sizes of the links that make up the chain are also expressed.
The weight of a running meter of the anchor chain is also calculated depending on the caliber using the coefficients: for a long link chain - 2, without buttresses - 2.2, with buttresses - 2.3.
The length of the chain depends on the type of vessel and its size. It should be much greater than the depth of the sea at the parking place, because, firstly, the severity of the part of the chain lying on the bottom helps the anchor to lie on the bottom and hold it there, and secondly, the force that acts on the anchor when it is hooked to the bottom, It should be directed not up, but horizontally.
Sea ships usually have anchor chains consisting of 10-13 bows with a caliber from 80 to 120 mm, which depends on the size of the anchor anchor. If the caliber is more than 15 mm, then the links are made with buttresses - a transverse jumper, which increases the strength of the link by more than 20%.
In addition to special meters, color markings are used on anchor devices. The number and color (white or red) of colored links depend on the number of etched meters or bows that make up the chain. The photo shows that one hundred and forty meters of the chain has been etched since two links are painted white on both sides of the Kenter's red staple. To determine the length of the chain in the dark, a benzel of soft annealed wire is superimposed on the buttress of the latter before the painted link.
Anchor Chain Parameters
The main parameters of the anchor chain are caliber, strength category, mechanical tensile loads and theoretical test mass. According to the design parameters, the links of the anchor chain are with and without buttress.
According to the strength characteristics, which depend on the caliber, material and manufacturing method, the anchor chain can be normal, high or high strength. Chains may differ in the method of manufacturing the links and spacers themselves.
Compliance with production standards is a prerequisite for the manufacture of anchor chains. For example, the anchor chain GOST 228-79 - a product with spacers, which is made of carbon and alloy steels, has approved mechanical properties, has a strength of three categories and the caliber of the main links with a spacer from 11 to 178 mm.
The quality of mechanisms, components and individual parts of anchor devices, including chains, is not only the reliability and safety of the vessel, but also a guarantee of safety, and sometimes the life of people on board it.