Introduction
A ship can weigh thousands of tons, yet it can stay in one place in the middle of the ocean. How is that possible?
The answer is simple: anchors.
An anchor is one of the most important pieces of equipment on any vessel. It allows ships to stop and remain in position without drifting away due to wind, waves, or currents. While many people think anchors simply rely on their weight, the real working principle is much more interesting.
In this article, we’ll explain how anchors work, what parts make up an anchor, and why the combination of anchor design, seabed conditions, and anchor chain length all play an important role in keeping a ship safely in place.
What Is an Anchor?
An anchor is a heavy metal device that connects to a ship through a chain or rope. It is lowered to the seabed to prevent the vessel from drifting.
Most modern anchors are designed to dig into the seabed, creating resistance that holds the ship steady.
Although anchor designs vary, most anchors include several key parts:
Shank
The long central bar of the anchor that connects to the chain.
Flukes
These are the pointed or curved parts that dig into the seabed.
Stock (on some traditional anchors)
A crossbar that helps the anchor land on the seabed in the correct position.
Anchors are typically used together with an anchor chain, which helps the anchor maintain the proper pulling angle and improves holding power.
The Basic Principle Behind Anchors
Contrary to popular belief, anchors do not hold ships in place simply because they are heavy.
Instead, anchors work because they grip the seabed.
When an anchor is dropped to the ocean floor, the vessel slowly moves back due to wind or current. This movement pulls the anchor along the seabed. As it moves, the flukes begin to dig into sand, mud, or clay.
Once the anchor buries itself, it creates strong resistance against further movement. This resistance is known as holding power.
Several factors influence how well an anchor works:
Seabed type
Soft seabeds like sand or mud allow anchors to dig in easily. Rocky bottoms can make anchoring more difficult.
Anchor design
Different anchor shapes are designed to perform better in different seabed conditions.
Anchor weight and size
Larger vessels require larger anchors to provide sufficient holding power.
When these elements work together properly, the anchor can securely hold even very large ships in place.
The Role of Anchor Chain and Scope
The anchor chain is just as important as the anchor itself.
If the chain were pulled straight up, the anchor could easily be pulled out of the seabed. To prevent this, ships release a longer length of chain so the pull on the anchor stays horizontal rather than vertical.
This relationship between chain length and water depth is called the scope.
For example:
- In calm conditions, vessels may use a 5:1 scope (five meters of chain for every meter of water depth).
- In rough weather, ships may extend the chain to a 7:1 scope or more.
A longer chain helps in several ways:
- It keeps the pulling force low and horizontal.
- It absorbs shock from waves and wind.
- It increases the stability of the anchored vessel.
Because of these benefits, the anchor chain plays a critical role in the overall anchoring system.
Different Types of Anchors
Over time, engineers have developed many anchor designs to improve performance in different conditions. Some of the most common types include the following.
Stock Anchor
The stock anchor is the classic design often seen in old maritime illustrations. It includes a horizontal bar called a stock, which forces the anchor to land on its side so the flukes can dig into the seabed.
Although reliable, this design is less common on modern commercial ships.
Plow Anchor
The plow anchor has a shape similar to a farming plow. It can dig into the seabed as the ship moves slightly backward.
This design works well in sand and mud and is widely used on many vessels.
Fluke Anchor
Fluke anchors have wide, flat blades that can bury deeply in soft seabeds. Because of their strong holding power relative to weight, they are popular on smaller boats and recreational vessels.
Claw Anchor
The claw anchor features a curved shape that allows it to reset itself if the boat shifts direction. This makes it a dependable option in areas with changing wind or currents.
Each anchor design has advantages depending on seabed conditions and vessel size.
What Happens If an Anchor Drags?
Sometimes an anchor fails to hold the vessel securely. When this happens, it is called dragging anchor.
Several factors can cause an anchor to drag:
- The seabed may be too hard or rocky
- The anchor may not have fully set
- The anchor chain may be too short
- Strong winds or currents may exceed the anchor’s holding power
When dragging occurs, the vessel may slowly drift away from its intended position. This can be dangerous, especially in crowded anchorages or near ports.
To solve the problem, crews may:
- Drop the anchor again
- Release more anchor chain
- Use a second anchor for additional holding power
Proper anchoring procedures are essential for maritime safety.
Why Anchoring Safety Matters
Anchoring may seem simple, but it plays a major role in marine safety and operations.
Large ships often anchor near:
- busy ports
- offshore platforms
- ship-to-ship transfer areas
- waiting zones outside harbors
In these situations, vessels must remain stable and avoid accidental collisions. Protective equipment such as marine fenders is often used in addition to anchoring systems to reduce impact risk when ships operate close to each other.
By combining a reliable anchor system with proper safety equipment, vessels can maintain safe positioning even in challenging marine environments.
Conclusion
Anchors are simple but powerful tools that allow ships to stay in place in open water. Rather than relying on weight alone, an anchor works by digging into the seabed and creating strong holding power.
The effectiveness of an anchor depends on several factors, including anchor design, seabed conditions, and the length of the anchor chain. When used correctly, this system can securely hold even massive vessels against wind, waves, and currents.
Understanding how anchors work helps explain one of the most fundamental systems in maritime operations—and why proper anchoring remains essential for safe navigation and marine safety.