Basic introduction to the role and composition of anchors Anchor casting method
marineusedgood hereby make the brief summary of basic introduction to the role and composition of anchors, which includes anchor casting method, types and characteristics of anchors, anchor loss and prevention for the reference.
Anchor casting method
Ship anchoring is a common method of berthing. The process is roughly as follows: the anchor connected by the anchor chain or cable is dropped into the water to land on the ground and bite into the soil. The holding force produced by the anchor is consolidated with the water bottom, and the ship is firmly anchored in the predetermined position. Different waters, meteorological conditions and operational requirements, and anchor casting methods are different. Commonly used methods include first anchor, tail anchor, and end anchor.
1. The bow of the ship broke down
Bow anchored, there are two types: single anchor and double anchor. Under normal circumstances, a single anchor can be used to fasten the ship, and the double anchor can only be dropped when the wind and waves are particularly heavy and the anchorage is narrow. When the bow of the ship is anchored, the hull receives the least external forces such as wind force, current force and wave impact force, so this method is the main method of anchoring and mooring, and it is also the main reason why the main anchor is arranged in the bow. Generally, there is only one bow anchor on small boats and fishing boats. In addition, any ship is equipped with two main bow anchors at the bow. When the ship reaches a certain length, a spare main anchor, also known as wind-resistant anchor, should be provided on the ship.
2, the stern of the ship broke down
Anchored at the stern is mostly used for inland vessels and landing craft. When the inland river vessel sails downstream and anchors downstream, in order to ensure safety and avoid turning around, the stern anchor is often used. In the operation of the landing ship retreating from the beach, with the cooperation of the main engine, the ship on the beach was pulled down the beach by the pulling force of the windlass.
3, anchored end to end
If you want to make the anchored ship always use the ship's side, when facing the wind direction, use the method of anchoring head and tail. The method of anchoring head and stern is generally to throw the main anchor from the direction of the wind, from the stern, pass a cable around the outboard of the ship and connect it with the thrown out main chain, and then release some main chain. Another method Yes, after the head anchor is thrown, the tail anchor is thrown from the tail. The stern anchor is usually transported and dropped by a small boat. The stern anchor is generally smaller than the main anchor, about 1/3 of the main anchor.
Types and characteristics of anchors
There are many types of anchors, roughly divided into four types: rod anchors, rodless anchors, large claw force anchors and special anchors. There are more than ten types of anchors.
1, with rod anchor
An anchor with a cross bar is a bar anchor. The characteristic of this type of anchor is that an anchor claw bites into the soil. When the anchor is towed on the seabed, the crossbar can prevent the anchor claw from tipping over and play a stabilizing effect. There are naval anchors, layer Luomen anchors, single claw anchors and Japanese anchors among the rod anchors.
Navy Anchor: It is a typical rod anchor with the longest service time, also known as an ordinary anchor. This kind of anchor has a large holding power and can firmly hold all kinds of soil, but it is inconvenient to retract. It is no longer used as a main anchor on modern large ships. It is only used as a main anchor on sailboats and small inland river vessels, as well as on naval lifeboats and engineering ships. , Can be used as a job positioning anchor.
La Luomen anchor: It is a navy anchor whose claws can be rotated. In use, when one claw enters the soil, the other claw can be turned to the anchor handle and close tightly. This kind of anchor is more convenient to use than navy anchors, but its grip is lower than that of navy anchors. Only one bolt is used to connect the anchor handle, which is inferior in safety. Therefore, it can only be used on sailboats and inland vessels, and the anchor weight is generally not more than one ton.
Single claw anchor: Similar to the navy anchor, only one claw, but its size is larger. The claw force of this kind of anchor is greater than that of the navy anchor. A variety of anchors for engineering ships, which are commonly used by dredgers, to ensure that the ship does not move during dredging operations.
Japanese anchor: It is a double-claw anchor used on Japanese fishing boats. The cross bar is fixed under the anchor crown. This not only maintains the advantage of large holding power, but also facilitates storage.
2, rodless anchor
The two-claw anchor with no crossbar and the anchor claw can rotate is a rodless anchor. The characteristics of this type of anchor are that the two claws bite into the soil at the same time during work, the stability is good, the adaptability to various soil qualities is strong, and the storage is convenient. Rodless anchors have developed rapidly, from the first generation to the third generation. Commonly used rodless anchors mainly include Hall anchors, Spaker anchors, AC-14 anchors and DA-1 anchors, as shown in Figure 4.
Hall anchor: Hall anchor is the first generation of modern standard rodless rotating claw anchors. The anchor is simple to manufacture, convenient to store, larger in grip, and good in grip. It is the object of choice for the main anchor of large and medium-sized ships, and our country likes to use this anchor.
Spaker anchor: It is an improved type of Hall anchor, and its structure is characterized by an anchor crown plate and reinforcement ribs at the anchor crown. Therefore, the claws of this kind of anchor can easily turn to the ground, have better stability, and do not scratch the ship's outer plate when storing.
AC-14 type anchor: It is called the second generation of rodless anchor. The anchor crown is very wide, the anchor claws are thick and long, and have longitudinal edges. This kind of anchor has a large weight and a large holding power. Good stability. It is often used as the main anchor of large container ships, automobile carriers and super large oil tankers. It is a commonly used anchor in Europe, America and Japan.
DA-1 anchor: AD-1 anchor is called the third generation rodless anchor, which is the most stable and most advanced anchor in the world. The anchor crown is wide and the end is triangular. The claws are very long and are inverted V-shaped with two inclined planes. The distance between the two claws is very small. This kind of anchor has the most suitable angle of engagement and a large engagement area. , Large holding power, good grip, strong stability, and convenient storage. Because DA-1 type anchors are almost entirely composed of straight slopes, there is less sediment and easy washing when anchoring. The Japanese shipbuilding industry considers this type of anchor to be the most ideal , The most promising anchor.
3, high holding power anchor
high holding power anchor is actually a kind of anchor with rod and rotating claw, because it has a large holding weight ratio, it is called high holding power anchor. The characteristics of this type of anchors are that the ground area of the anchor claws is large, the bottom material to be grasped is deep and much, and the holding power is extraordinary, but the anchor claws are easy to pull and it is inconvenient to store. The high-holding anchors include Markov anchors, Danfore anchors, speedboat anchors, Starlinger anchors and Starto anchors.
Markov anchor: The structural feature of the Markov anchor is that the anchor claw is wide, and there is a stabilizer bar on the outside of the middle of the claw. In order to prevent the rock from being stuck on the anchor claw, the inside of the claw is made into an arc shape. Markov anchors have two manufacturing forms: welding and casting. Both types of anchors are commonly used in our country.
Danfore anchor: Similar to the Markov anchor, except that the stabilizer bar is arranged on the top of the anchor. It is said that the grab-to-weight ratio of this anchor is particularly large, about three times that of the naval anchor.
Starlinger anchor: Its structural feature is that the stabilizer bar is designed to be inclined, and the distance between the two claws is large to prevent the anchor claws from being jammed by gravel.
Speedboat Anchor: As the name suggests, it is the anchor used by speedboats. Its structural feature is that the two claws are relatively close, the crossbar is installed on the outside of the claw, and the anchor crown is small. This anchor has a great grip, but the crossbar is easy to bend.
Star Anchor: It is a new type of high-holding anchor with a grip-to-weight ratio of 15-20. The anchor claw is particularly wide, and the cross bar is located at the anchor crown, which is welded. The difference from other anchors is that there is a detachable wedge to change the angle of rotation of the claw.
4, special anchor
The shape and purpose of special anchors are different from ordinary anchors. Mainly refers to the permanent mooring anchors used for pontoons, boat storage, floating docks, etc.; ice anchors used on icebreakers and floating anchors used on sailing ships and small boats.
Anchor loss and prevention
The loss of an anchor on a ship is the same as the loss of a propeller cap. An anchor is connected by an anchor shackle and an anchor chain, so there are two situations in which the anchor is lost. One is caused by the anchor shackle, and the other is caused by the anchor chain.
1. Caused by anchor shackle
The anchor shackle is made of steel, which is forged or welded, and has a pin on it. Anchors are generally hung outboard on both sides of the bow. Due to the long-term impact of strong wind and waves and the impact during retracting, the pins may loosen and come off. When the pin is disconnected, the anchor is lost.
2, caused by anchor chain
Anchor chain has been used for a long time and wears severely. When the anchor is dropped on the hard substrate and the anchoring speed is too fast, the anchor will break and the anchor will be lost. The loss of the anchor can be prevented. The anchor shackle should be carefully checked before the ship sails. If it is loose, deal with it in time. The anchor chain shall be overhauled and replaced on time according to the requirements of ship inspection. As long as the above two points are achieved, plus the appropriate speed when lifting the anchor, the anchor will not be lost.
With the development of science and technology and the shipbuilding industry, new types of anchors will continue to appear, which will provide a reliable guarantee for the safety of ships.
Only when the anchor chain is inclined at a certain distance from the ship, can it have the pulling force to fix the ship. So the first thing to do when anchoring is to solve this problem.
Start the windlass to tighten the anchor chain, and the ship moves towards the iron anchor. When the anchor link is nearly vertical, the iron anchor is retracted.
If both the front and rear anchors are lowered, first loosen one chain, tighten the other chain, lift out one anchor, and then lift another anchor.
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