The keel of a ship is a large, longitudinal beam or plate that runs along the centerline of the vessel from bow to stern. It is usually the first part of the ship’s hull to be constructed and is the foundation upon which the rest of the vessel is built.

The keel provides stability to the ship, both in terms of its ability to resist capsizing and in its ability to maintain a straight course. It also serves as a structural support for the frames, plating, and other components of the ship.

In addition, the keel often contains ballast tanks or compartments that can be filled with water or other materials to adjust the ship’s trim and stability. In modern ships, the keel may also house various types of machinery, such as the propulsion system, steering gear, or fuel tanks.

  1. The shape and size of the keel can vary depending on the type of ship and its intended use. For example, a sailing ship may have a deep, V-shaped keel to provide stability and prevent leeway (sideways drift), while a modern cargo ship may have a flat-bottomed keel for shallow-water navigation.
  2. The keel is often made of steel or another strong, durable material to withstand the stresses of sailing. In some cases, the keel may be reinforced with additional structures or materials, such as fiberglass or carbon fiber.
  3. The keel may also include a bulb or fin at the bottom to improve the ship’s stability and performance. These features help to reduce drag and improve the ship’s ability to maintain a straight course.

Finally, the keel is an important symbol of a ship’s strength and endurance. In many cultures, the keel-laying ceremony is a significant event that marks the beginning of the ship’s construction and is often accompanied by various traditional rituals and blessings.

The keel of a boat helps in the overall control of its navigation, primarily in terms of providing longitudinal stability by letting it move forward and backward without losing control of the vessel. Another component of the vessel, other than the keel, providing lateral stability is the ‘rudder’, which is also an essential part of the hull.

Mechanism of the Keel

The keel consists of a flat foot in the bottom center of a vessel with a flat edge. On either side of the structure lies the ballast stones, which are essentially two round weights. These ballast stones are connected to the keel with the help of an iron rod. The ballast stones consist of lead. Thus, the weight supplied by the lead balls in the ballast stones keeps the boat from capsizing.

The keel of a ship

The keel of a ship lay generally underneath the ship, all throughout its length. Just like how the backbone is to us human beings, so is the keel to a ship. It is the primary component of a ship. It is the first thing that is placed on the blocks during the construction of the ship.

Types of Keels of Ships

  1. Full keel – a long, continuous keel that runs from the bow to the stern, providing maximum stability and directional control.
  2. Fin keel – a long, narrow keel that extends down from the bottom of the hull, providing stability and control while also reducing drag and improving performance.
  3. Bulb keel – a variation of the fin keel that features a bulbous weight at the bottom to improve stability and reduce the keel’s overall length.
  4. Wing keel – a fin keel that has additional lateral wings extending out from either side, providing even greater stability and maneuverability.
  5. Bilge keel – a pair of short keels attached to the sides of the hull near the stern, providing stability and reducing the vessel’s rolling motion.

The choice of keel type depends on factors such as the vessel’s intended use, size, and design, as well as the local water conditions and the preferences of the boat’s owner or designer.

Types of Keels on Ships

Bar Keel:

It is the foremost type of keel constructed on ships made of iron. But they carry the disadvantage of not providing the big vessels with sufficient strength and stability. The keel consists of a bar placed in the center of the keel.

The bar keel is attached to either side of the hull and these ends are known as Garboard strake. The depth of a bar usually falls between 3 to 6 times its own width. Bar keels are mostly useful for vessels that are vulnerable to grounding, for example- ferries or boats.

Duct Keel:

Duct keels are also known as “box keels”. Throughout the length of the keel, it allows pipes and other services. These keels are mounted between the front portion of the engine room bulkhead and the aft of the collision bulkhead. Duct keels are placed in double-bottom hull ships. The structure of a duct keel is made of solid plates welded into a box shape.

These box keels then create an internal watertight passage running longitudinal to the length of the vessel. Access to a duct keel is usually done through a watertight manhole at the forward end of the machinery space.

Flat Keel:

Flat keels are a modern invention utilized across all types of sea vessels. The structure is made of a solid plate, supported by frames surrounding the vessel. They are flexible to be fitted onto vessels using both a single bottom and a double bottom hull. Flat keels must be of a full uniform thickness of exactly 3/5th of length, toward the center of the ship. It should also be thicker than the adjoining plates.


Keels are a vital part of any vessel, boat, or ship, large or small. It provides a vessel with stability and strength. Keels impart easy maneuvering capabilities for your vessel.

It protects the vessel from tipping over into the water, while also protecting it from slipping forward or sideways. The choice of keel used in a vessel determines its performance of the vessel. The right choice of keel can protect the vessel from having a compromised ocean capability.

New innovation provides pragmatic techniques and engineering that uses materials of high quality and capacity in the making of different types of keels. If you are unsure of the choice of the keel to be used on your vessel, consulting a professional is important.


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