1. The anchor chain has to work. The most basic condition is to hook things on the seabed. If the anchor chain is not long enough, the anchor will not work. If the bottom of the sea is flat, or if the hook is not fixed, or the hook is not strong, if it is calm, if the waves are too large, the anchor will not catch anything, and the anchor will lose its effect. This is called "walking anchor". It is very dangerous when the ship is anchored during the anchoring, because the ship usually stops when the ship is anchored. If it is to be opened immediately, it takes time, and the ship without power is drifting around. dangerous. Therefore, the concept of anchorage, the anchorage, the meaning of the words, the rough under the sea, and the need to avoid the wind.
2. The weight of the anchor chain is negligible for the ship, and the friction will not play much role. Generally speaking, the ship and anchor chain are all straight when anchoring, which is basically negligible friction. If you are by the sea, you will find many small fishing boats whose anchor chains are thick ropes.
3. On the top of the ship, the anchor chain is straight, but there is a section under the water that is close to the seabed (in fact, it is attached to the sea floor). The anchor provides the grip force and then transmits it to the ship through the anchor chain to resist the influence of the external load of the current and the wind and waves on the positioning. The reason why the section is attached to the sea bottom is to take into account the influence of the force. Think about it, an anchor, the anchor chain is quite straight and easy to walk. And there is a section on the bottom of the sea that can provide a margin within a certain range.