When using ships, we naturally think of anchor chains and anchors. To ensure a reliable offshore experience, however, we also need to acquire some specialized knowledge. Currently, welded anchor chains are widely used in commercial vessels. Almost all anchor chains are manufactured by flash welding, while cast anchor chains are rarely employed. With the exception of most forged components found in anchor chain fittings, forged anchor chains have largely been phased out. So, what kind of anchor chains and anchors should be equipped on seagoing vessels?

Based on the type of vessel, the waters in which it will navigate, and the data listed in the relevant regulations, the anchor and anchor chain for seagoing vessels should be selected according to the vessel’s size. The variable N (equipment number) or the number of vessels is a parameter that reflects the wind and current forces acting on the hull.

Equipment such as cargo ships, bulk carriers, tankers, cutter suction dredgers, and ferries shall be selected according to n. From the perspective of quantity assembled, the number of anchors that a vessel should be equipped with, the weight of each anchor, the horizontal length of the anchor chain, the total length and diameter of the anchor chain—specifically, if the vessel is required to be equipped with a certain total number of anchor chain links, the right-hand anchor should be fitted with more links. Each cargo ship weighing 10,000 tons or more must be equipped with at least 10 anchor chains.

Generally, vessels operating in unlimited navigation areas should be equipped with 12 anchor chains per main anchor. In addition, a vessel should retain at least one anchoring shackle and four connecting shackles or connecting chain links; another anchor chain should be fitted with a large floating shackle. AM1-grade chains with tensile stresses below 400 N/mm² must not be used for large-grip anchoring systems. AM3-grade chains are suitable only for anchoring chains with diameters of 20.5 mm or greater.

Types and models of anchors: Hall anchor, Sbark anchor, Japanese poleless anchor, AC-14 large-hold anchor, Delta anchor, Triangular anchor, Naval anchor, Naval anchor, Danforth anchor, Danvers anchor, Maris large-hold anchor, Single-claw anchor, Four-claw anchor, Positioning anchor, Bell anchor, Boll anchor, MK3 anchor, MK5 anchor, MK6 anchor, Naval anchor, Pear-shaped anchor—these are some of the commonly used marine anchors. Additionally, there are offshore engineering anchors and aquaculture anchors for fisheries.

An anchor chain consists of numerous links connected together, and its size is approximately equal to the chain diameter (in millimeters). Depending on whether the links have gears in the middle, anchor chains can be classified into two types: gear-equipped anchor chains and gearless anchor chains. Anchor chains can be manufactured through forging, casting, and welding. A marine anchor chain comprises several segments, each segment measuring between 25.0 and 27.5 meters in length and connected by links or shackles. After anchoring, the anchor chain is stored in the ship’s chain locker. The specifications of the anchor chain shall be confirmed in accordance with the shipbuilding standards.

Today, many technologies and techniques have been improved, and there are numerous specifications for marine anchor chains and their configurations. According to Chinese codes and standards, the joints of stepped anchor chains are connected using Kent shackles, while the joints of non-stepped anchor chains are connected using connecting shackles. The enlarged link in a non-stepped anchor chain is an enlarged link that is larger than a standard link.