The length of the marine anchor chain is in units of "knot", we stipulates that the standard length of each section of anchor chain is 27.5m in our China, and the imperial countries often take 15 extensions as a section,  whichequivalent to 27.5m of meters. There are also sections of 25m and 20m.

A complete marine anchor chain is composed of three kinds of links: anchor end link, mid link and end link. In addition to the swivel links, the number of links of each anchor chain should be odd to ensure that the connecting link or joining shackle can lie flat in the hole of the sprocket when passing through the windlash sprocket. 'Yingxun', or also called 'Tuo', which is a unique unit of length used at sea, 1 xun is about equal to 1.8288 meters, which is about the length of a person's (of course, white European) arms outstretched, an anchor chain takes 15 xun, that is, more than 27.43 meters, when converted to metric, erase the tail number behind, directly take 27.5 meters. So this convention has been followed.  Usually the outfitting selects the anchor chain length L according to the outfitting number N. The length of an anchor chain is 27.5 M , and when the L selected according to the outfitting number is an even multiple of 27.5 M, the left and right anchor chains are equally long, and when it is odd times, the starboard side is 27.5 more than the left side.

Generally, the anchor chain of a ship is 27.5 meters, each anchor will be  equipped with 10 to 11 anchor chains, and the length of the whole chain is about 300, so the anchor is generally in the shallow water area of about 30 meters deep, the anchor chain undercover has friction to play a role, and the anchoring site is generally anchored in the special anchorage planned by the port authorities!