What Is The Composition of Anchor Chain And How Should It Be Marked?

Anchor chain is the component of an anchor that connects it to a ship or structure, anchor rod (or anchor cable). It is made up of several chain links that form a closed loop. Each ring is joined to the ring next to it, resulting in a chain of arbitrary length. The anchor chain's purpose is to secure the anchor to a portion of the ship so that it may be readily pulled up when needed. So, what exactly is an anchor chain made up of? When raising the anchor, how can you rapidly determine the length of the anchor chain in the water? The purpose of this article is to discuss the composition and marking of anchor chains.

What is the composition of anchor chain and how should it be marked?

1. What is the structure of anchor chain?

Anchor chain is a chain that connects the anchor to the hull and is used to transmit and cushion external forces to the ship.

A complete anchor chain is made up of multiple sections of anchor chain that are linked together by connecting links or connecting shackles, and each section of anchor chain is made up of many links.

The anchor chain is classified into two varieties based on the construction of the chain ring: stud link chain and studless chain. When the size and material are the same, the strength of stud link chain is stronger than that of studless chain, the deformation is smaller, and the stacking is not easily twisted. As a result, it is commonly utilized on sea ships. Studless chains are typically used on tiny vessels.

The anchor chain is classified into three types based on its manufacturing method: casting anchor chain, electric welding anchor chain, and forging anchor chain. The welding anchor chain is the most commonly used in modern shipbuilding, while the casting anchor chain is rarely utilized and the forging anchor chain has nearly disappeared. The steel grades of stud link chain anchor chains used to manufacture stud link chains are classified as AM1, AM2, and AM3. AM1 anchor chain steel is a calming steel that cannot be used for high-holding anchor and super-large holding anchor. AM2, AM3 anchor chain steel is soothing fine crystal treatment steel, and AM3 anchor chain is only appropriate for anchor chain with a chain diameter of 20.5mm or greater. If high-strength steel is used on the same ship, the size of the chain link can be appropriately lowered.

Anchor chain rings are classified into regular rings, expanded rings, chain end rings, swivel forerunners, chain end shackles, and connecting shackles based on their function.

The diameter of the chain ring d is used to express the size of the chain ring, as seen in the image below. The standard stud link chain ring has a cross-sectional diameter of d, a length of 6 times the diameter d of the cross-section of the chain ring, and a width B that is 3.6 times of d. The expanded chain ring is 6.6d in length and 4d in width. Kenter shackle is 6d long and 4.2d wide. Ordinary chain link is the standard link for assessing the strength of anchor chain. The diameter of an ordinary chain link indicates the strength of an anchor chain.

What is the composition of anchor chain and how should it be marked?

The length of anchor chain is "section," and the standard length of each section of anchor chain is 27.5m, with an odd number of rings in each section.

Connecting rings or connecting shackles are used to join chain links. If connecting rings are used to join each part of the anchor chain, the connecting rings' two ends are regular chain links. To ensure a smooth transition of strength, if connecting shackles are used to connect each section of the anchor chain, both ends of the connecting shackles are attached to the end ring (also known as studless chain) in turn, the ring is extended, and then the ordinary ring is connected.

The stud link chain is mostly made up of stud rings, whereas each anchor chain is made up of anchor end rings, middle rings, and end rings. Ordinary rings, expanded rings, end rings, connecting rings or connecting shackles, swivel forerunners, and end shackles make up a full anchor chain.

The anchor end link is the initial anchor chain link that is attached to the anchor. In this link, the end shackle and anchor shackle should have the cross pin facing the anchor and the arc part facing the middle link. To decrease friction and jamming, the ring pin of the swivel should face the middle link. The swivel is placed to prevent the anchor chain from twisting excessively.

The chain end ring is the anchor chain's final link and is attached to the chain discarder. The swivel ring bolt should also face the middle link.

When the anchor is thrown up and passes through the chain holding wheel, the circular part of the link shackle should face the anchor to minimize leaping, impact, and jamming.

What is the composition of anchor chain and how should it be marked?

2. How Should an Anchor Chain Be Marked?

Mark each connecting link and its nearby stud links to immediately recognize the loose length of the anchor chain when putting up the anchor and to grasp the length of the anchor chain in the water when starting the anchor.

The procedure is as follows:

Wrap the metal wire (or white steel ring) around the front and back of the first chain link, and then wrap the wire between the first and second portions.

White paint on the chain link and red paint on the connecting link denote the first link.

Wrap wire (or a white steel ring) around the second stud link on the front and rear of the connecting connection between the second and third links. Also, paint white on all the stud links that join two chain links, and red on the connecting links that connect to the second link.

And so on through the fourth and fifth quarters. Repeat the same approach for the first section to the sixth section to mark, beginning with the connecting connection between the sixth and seventh sections.

To prevent anchor loss, the last one to two sections can be painted red or yellow to indicate that the anchor chain has reached the end of the hazard.

What is the composition of anchor chain and how should it be marked?

National classification societies' anchor chain grade comparison table

Name of the anchor chain National classification society anchor chain gradeCCS LR ABS DNV GL BV NKAM1 U1 Grade1 NVK1 GL-K1 BV-Q1 Grade1 Grade 2 stud link chain AM2 U2 Grade2 NVK2 GL-K2 BV-Q2 Grade2 Grade 3 stud link chain AM3 U3 Grade3 NVK3 GL-K3 BV-Q3 Grade3

Some frequently asked questions about anchor chains

Question 1: Why is it necessary for the number of links in each anchor chain to be odd?

Kenter shackles are used to attach each anchor chain and are greater in size than other stud link chains. We know that the connection between each anchor chain link is 90° vertical. That instance, one chain link should be horizontal, followed by a vertical chain link. There is also a horizontal groove and a vertical groove when creating the anchor chain plate of the windlass. The anchor chain leans on the horizontal groove as the sprocket pulls it upward. Having difficulty driving the anchor chain upwards. Because the Kenter shackle is relatively fat, it can only lie in the horizontal slot and cannot be trapped in the vertical slot. If the vertical slot is widened to accommodate it, other conventional links will loosen in it.

When the number of links per link is odd, the Kenter shackle attached to it will always be on an even number. The Kenter shackle will thereafter always fall into the horizontal groove. If the number of links is even, the Kenter shackle will alternate between the odd and even rings. Then it will be in the horizontal groove for a while and then in the vertical groove for a while, which, according to the preceding explanation, will not work.

What is the composition of anchor chain and how should it be marked?

Why do certain ships have a varying number of anchor chain links between port and starboard?

The number of anchor chains on the ship has been estimated, and this number is then divided by 27.5m using the final outfitting computation to find the equivalent anchor chain length required. If the number is an even number, it is split evenly between port and starboard. If the number is an odd number, there is only one extra section on one side, usually the port side. Because it is believed that the water on the port side was formerly closer to the port, the water on the starboard side will be slightly deeper, therefore add a little more section to the starboard side.