The selection of anchor chain length is not made arbitrarily. It requires comprehensive calculation based on the type of the vessel, the water environment of the anchorage area, and the hydrological conditions. When a vessel temporarily docks in rivers, lakes, or other water bodies, anchoring is a common method to fix the ship's position. If the ratio between the anchor chain length and the water depth is inappropriate, it may cause the vessel to drift with the current, or even lead to grounding or collision accidents. 

The formula for calculating the length of anchor chain 

The relationship between the length of the anchor chain and water depth can be determined by the following formula: [ h = d \times k + \frac{2}{3} \times h_w ]

Among them: 

(h): Minimum depth of the anchorage at low tide (meters) 

(d): Maximum draft of the vessel (meters) 

(k): Safety factor (1.2 for no wave conditions, 1.5 for wave conditions exist); 

(h_w): Maximum wave height (can be ignored when there is no swell). 

Anchor limitation in deep waters: In deep water areas, the total length of the anchor chain must not exceed one quarter of the water depth. Otherwise, the anchoring force will significantly decrease, causing the vessel to be unable to maintain a stable mooring. 

Response strategies in special scenarios 

The anchoring of warships in the open sea:

Warships in the open sea usually do not anchor but instead adopt a "drifting" mode. By shutting off the engines or operating at the minimum power level, they utilize the ship's own weight and stability to withstand wind and waves. Moreover, the long-term anchoring of warships for extended periods is not in line with the operational requirements for combat. 

The navigation characteristics of an aircraft carrier:

When an aircraft carrier sails in the deep sea, it almost never uses anchors. The reasons for this include: 

The length of the deep-sea anchor chain is insufficient, and the anchoring force cannot be fully exerted. 

The hydrological conditions in the unfamiliar sea area are complex. Randomly anchoring the boat may result in running aground or getting into danger. 

The tasks of aircraft carriers are mostly dynamic and require frequent adjustments of the course to deal with unexpected situations.