There are many types of anchors, and each country has formulated its own classification standards based on the characteristics of the anchors. Generally, they are classified according to the presence or absence of a crossbar, whether the anchor claws can rotate, the gripping-to-weight ratio, and the purpose of the anchor.
Ordinary Mast Anchor
Ordinary mastless anchor (1. with fixed anchor claws; 2. with rotating anchor claws)
High gripping-to-weight anchor (1. with mast; 2. without mast)
Special Anchors
(1) Mast Anchor (Naval Anchor)
Structural characteristics: The anchor shaft and anchor claws are a single unit, and the anchor claws are fixed and do not rotate. There is a fixed or foldable crossbar on the anchor shaft, which is perpendicular to the plane of the anchor claws.
Advantages: ① Simple structure, large gripping-to-weight ratio, generally 4-8, with a maximum of 12; ② Good bottom gripping stability, adaptable to various bottom types.
Disadvantages: ① The upward-curving claw is prone to tangling with the anchor chain, and it can easily damage the bottom of the ship in shallow anchorages; ② It is not convenient to drop and store the anchor. It cannot be stored in the anchor chain canister, causing entanglement of the anchor chain and threatening other ships.
Application: Not suitable as a bow anchor. Mostly used on small boats and sailboats.
Single-claw anchor: Similar to a naval anchor, it has only one claw, but it is larger. This type of anchor has greater claw strength than a naval anchor. It is used as a positioning anchor for various engineering vessels, and is commonly used on dredgers to ensure the vessel does not move during dredging operations.
Laminar anchor: A naval anchor with rotating claws. In use, when one claw enters the soil, the other claw rotates to the shank and holds firmly. This type of anchor is more convenient to use than a naval anchor, but its holding power is smaller, and it uses only one bolt to connect the shank, resulting in poor safety. Therefore, it can only be used on sailboats and inland waterway vessels, and its weight generally does not exceed one ton.
Japanese anchor: A double-claw anchor used on Japanese fishing boats, with the crossbar fixed below the anchor crown. This not only maintains the advantage of high holding power but also makes it easy to store.
(2) Ordinary Barless Anchor
The total weight of the anchor head (including the pin and swivel) (after deducting the weight of the anchor shaft and anchor shackles) should not be less than 60% of the total weight of the anchor. There are several types of anchors, including Hall anchors, Speck anchors, and stern-mounted anchors.
Hall anchor: The anchor shaft is made of forged steel, and the lugs are made of cast steel. It has no crossbar. The lugs and crown can rotate around a pin passing through a hole at the lower end of the anchor shaft. The lug angle is approximately 45°. Both lugs enter the soil simultaneously, with a holding weight ratio of 2.5–4, not exceeding 8. It has a simple structure, is easy to operate and store, but has relatively low holding power. It is prone to loosening the soil during current changes, which can cause the anchor to drag.
Application: Widely used as a bow anchor.
Speck anchor: An improved version of the Hall anchor. When retrieved, its lugs naturally point upwards and flip upon contact with the hull, preventing damage to the hull plating. Its characteristics include a large crown, low center of gravity, easy burrowing, and good stability, but the lugs are prone to rotation. It has low impact force, can be retrieved into the anchor chain canister, does not entangle the anchor chain, and does not damage other vessels. Its holding weight ratio is relatively low (1–2.5), and it is often used as a bow anchor.
Tail-wing anchor: Features a wide and thick gripping angle and a low center of gravity; low soil penetration resistance, good stability, wave resistance, and easy washing. Its gripping force, stability, and other performance characteristics are superior to Hall anchors and shell anchors. Widely used.
AC-14 type anchor: Known as the second generation of stockless anchors. It has a wide crown, thick and long claws, and longitudinal ridges. This type of anchor is heavy, has a high gripping force, and good stability. It is commonly used as the main anchor for large container ships, car carriers, and very large crude carriers (VLCCs), and is a commonly used anchor in Europe, America, and Japan.
DA-1 type anchor: Known as the third generation of stockless anchors, it is the most stable and structurally advanced anchor in the world. The anchor crown is wide and triangular at the end, with long claws in an inverted V-shape formed by two beveled surfaces. The distance between the two claws is very small. This type of anchor has the most suitable soil-engaging angle, a large soil-engaging area, high holding power, good gripping ability, strong stability, and is easy to store. Because the DA-1 type anchor is almost entirely composed of straight beveled surfaces, there is less mud and sand adhering when anchoring, and it is easy to wash. The Japanese shipbuilding industry considers this type of anchor to be the most ideal and promising anchor.
(3) High-holding-power Anchors
Divided into shank and shankless types. When used as the bow anchor, the anchor weight can be 75% of the corresponding ordinary anchor weight. Their common characteristics are wide and long claws, deep soil engagement, good stability, and a large holding-weight ratio.
Shank high-holding-power anchors combine the advantages of shank and shankless anchors. A stabilizing shank is provided at the anchor head to ensure the stability of the anchor gripping the bottom. They are generally used for softer bottoms and are inconvenient to store. Used for engineering work vessels and small boats.
Including: Danforth anchor (also known as swallowtail anchor), Steven anchor. Danforth anchors (also known as dovetail anchors) have claws that can rotate approximately 30° forward and backward, with a hold-to-weight ratio generally greater than 10. They are commonly used on engineering vessels (such as dredgers).
Steven anchors have short, large claws. The claw angle is adjusted by movable wedges mounted on the bolt, making them adaptable to various seabed types. Their hold-to-weight ratio can reach 17–34. They are frequently used as positioning anchors on oil platforms.
Boltless high-holding-force anchors improve upon boltless anchors by modifying the hold-up angle and claws.
The British-developed AC-14 type anchor features extremely thick and wide stabilizing fins, providing excellent stability, rapid soil engagement, and adaptability to various seabed types. With a hold-to-weight ratio as high as 12–14, it is widely used on very large ships or roll-on/roll-off ships with a large surface area above the waterline.
The Dutch-developed Bohr anchor: can be used as the bow anchor of large ships and the positioning anchor of engineering vessels; adaptable to various seabed conditions; stability is 30%-50% higher than that of a stockless anchor of the same weight; under the same holding force, the anchor weight is 25%-40% lighter than that of a stockless anchor; the general holding-to-weight ratio is around 6.
(4) Special Anchors
Function: Used for special purposes, such as permanent mooring of buoys, lightships, floating docks, and floating piers.
Types: Includes umbrella anchors, spiral anchors, single-claw anchors, and ice anchors for icebreakers, etc.
