The anchor chain is formed by connecting many chain links, and the size is expressed by the chain diameter (mm). According to the presence or absence of support in the middle of the chain link, it is divided into a filed anchor chain and a filed anchor chain. The anchor chain can be made by forging, casting and welding. The marine anchor chain is composed of several "knots" (shackles), each section is 25.0 ~ 27.5 meters long, and the sections are connected by chain links or shackles. After twisting the anchor, the chain is stored in the chain compartment at the bow of the ship. The specifications of the anchor chain are calculated in accordance with the ship building standards.