The boat is difficult for berthing when encountering the strong wind. It completely relies on boat anchor. The
marine anchoris the main component of the anchoring and mooring system. One end is fixed on the boat with a marine anchor chain, and the other end is a barbed claw shape, throwing to the bottom of water or shore to highly stabilize the boat.
Work Principle Of Marine Anchor
Marine anchor is composited of anchor buckle, anchor bolt, anchor stock, anchor handle, anchor wrist and the symmetrical part on both sides is called anchor fluke which is the most important part of the anchor to grab into the dirt. After the ship is anchored, the anchor is sinking to the bottom of water under the traction of the anchor chain. The plane where the anchor wrist is located is perpendicular to the water bottom with the anchor rod. At this time, the anchor fluke will be in contact with the bottom of the water.
The length of the ship anchor chain is often longer than the depth of the water, so the anchor chain in the water bottom has a lying- flat state. When the ship is disturbed, the anchor chain will be pulled. The anchor in the bottom of the water under the action of the horizontal force. The role of the anchor itself acts on the contact point of the anchor fluke and the water bottom. The two-force synthesis makes an anchor move downward, which is anchoring the process. After that the anchor is pulled into the bottom of the water, which can provide the ability for boat berthing.
The Categories Of Marine Anchor
The factors that should be considered for choosing the marine anchor include easy operation, convenient to store and economic application. The most important factor is the anchor grip. The anchor grip is different because of the anchor type and the submarine soil.
There are many kinds of marine anchors. According to the different structures and uses, the ship anchor can be classified into a stocked anchor, stockless anchor, high holding power anchor and special anchor. The bow anchor adopted by the merchant ship is a stockless anchor, while the stern anchor sometimes adopt a stocked anchor or a Danforth anchor.
1. Stocked anchor
The anchor has the advantages of a simple structure, large holding power to weight ratio and high grip stability, but it has inconvenient anchoring operation and storage with an anchor stock. Therefore, this anchor should not be used as a bow anchor for commercial ships, suitable as a stern anchor, generally used for small boats.
2. Stockless anchor
It is also known as the hall’s anchor and the generally adopted stockless anchors for merchant ship are Hall anchor and Spek anchor. The anchor fluke and anchor rod can rotate at a certain angle and is a stockless type. The holding power to weight ratio is 2.5 to 4 and the maximum is up to 8. The anchor has a simple structure, throwing anchor operation and storage conveniently, so it is suitable for the bow anchor with the widest applications. But it also has the disadvantage of a small anchor grip. The Hall anchor is the earliest used type and the Spek anchor is an improved type of Hall anchor, which has the advantage that its anchor fluke can be naturally upward.
3.High holding power anchor
It is combined with the advantages of a stocked anchor and a stockless anchor. Because of the large gnawing soil of the anchor fluke and the large gripping force, it is suitable for the sandy or soft water bottom. The commonly used HHP anchors are the Martrosov anchor and Danforth anchor which is characterized by the deep gnawing soil, high stability, with large anchor grip. But the strength of the anchor fluke is weak and easy to deform.
4.Special anchor
It has different shapes, compared to the general anchors, such as single claw anchor, screw anchor and mushroom anchor. It often has special applications, used in a permanent mooring such as a floating tube, a buoy, a lightboat, the floating dock and a floating wharf.
