Keel

A keel is the bottom part of a ship.

It runs from the front to the back. Builders often start with the keel. This is the first step to make a ship.

It helps the boat stay steady in the water. On some boats, it acts like a weight. This stops the boat from tipping over. The keel also helps the boat move straight. It is a very important part for every boat.

A keel is the bottom part of a ship. It is a long piece that runs down the middle. It goes from the front to the back.

In many places, building the keel is the first step. This is called laying the keel. It marks the start of making a new ship.

The keel helps a boat stay steady. On sailboats, it does even more work. It can act as a counterweight. This is a heavy weight that stops the boat from tipping.

A keel also helps a boat move straight. It works like a foil. A foil is a shape that moves through water to create lift. This lift helps fight the wind. The wind tries to push the boat sideways. The keel helps it go forward instead.

There are different kinds of keels. A flat plate keel is common on big ships. Some smaller boats use a bar keel. This is a thick, heavy type of keel.

A keel is the bottom-most part of a boat. It is a long piece that runs along the centerline. It goes from the bow at the front to the stern at the back. This part is very important for stability. Stability helps a boat stay steady in the water. On some sailboats, the keel does even more work. It can help the boat move through water or act as a heavy weight.

Building a ship often starts with the keel. This special event is called laying the keel. In British and American traditions, this marks the official start of construction. In the past, builders used the keel as a base. They would set up frames at key points along it. Then, they would attach a keelson to the keel using bolts or treenails.

Modern big ships are built differently now. Workers often make large sections of the hull first. They do not always build around a single keel anymore.

People have used keels for a very long time. We can see this in history from ancient times. A Greek merchant ship called the Kyrenia ship had a keel around 315 BC. Another old wreck called the Uluburun shipwreck was found from 1325 BC. That ship had a very simple keel that looked like a center plank. The word itself is very old too. Some scholars think it is one of the first English words ever written down. It was recorded by a man named Gildas in the 6th century.

There are many different types of keels used today. Most ocean-going ships use a flat plate keel. This is the most common kind you will see. Smaller boats like tugs or ferries might use a bar keel. A bar keel is very strong and heavy. This helps if the boat might touch the ground. Sailboats use special keels that work with the water. These are called hydrodynamic keels. They can be fixed in place or they can move.

On a sailboat, the keel has three main jobs. First, it acts as an underwater foil. This helps the boat move forward instead of sliding sideways. Second, it acts as a counterweight. The wind pushes on the sails and tries to tip the boat over. The heavy keel helps keep the boat upright. Third, it can act as a bilge keel. This allows the boat to sit on mud or sand. Some keels can even pivot or swing to help the boat sail better.

A keel is the bottom-most longitudinal structural element of a watercraft. It runs along the centerline of a ship from the bow to the stern. This component is vital because it provides essential stability for the vessel. In many shipbuilding traditions, the process of "laying the keel" marks the official start of construction. This event signifies the moment the ship's foundation is placed in its cradle.

The way a keel is used depends on the construction style. In carvel-built hulls, builders start by laying the keel, then the stern and stem. They then set up frames at key points along the keel. A keelson is later attached to the keel using bolts or treenails. Other methods, like clinker construction, use overlapping planks to shape the hull. In the classical Mediterranean period, builders used mortice and tenon joints to connect planks edge-to-edge. In those older systems, the planking itself provided much of the hull's strength.

There are different types of structural keels used in modern maritime engineering. The most common version is the flat plate keel. This type is typically fitted to ocean-going ships and most large vessels. Smaller boats, such as tugs, ferries, and trawlers, often use a bar keel. A bar keel has massive scantlings, which refers to its thick and heavy dimensions. While this makes it strong for grounding, it increases the vessel's draft. A draft is the depth of the ship below the water line.

Modern shipbuilding has changed how these foundations are handled. Large ships are no longer always built around a single, central keel. Instead, many are constructed using pre-fabricated, complete hull sections. In these cases, the construction process begins with the cutting of the first sheet of steel. This differs from the traditional method where the keel is the very first piece placed. Regardless of the method, the keel remains the central structural member of the hull.

History shows that keels have been used since antiquity. The Uluburun shipwreck, dating to 1325 BC, had a rudimentary keel. This may have been a simple center plank rather than a true keel. Evidence of a more developed keel appears in the Kyrenia ship, a Greek merchant vessel from 315 BC. The word "keel" itself has a very long history. Some scholars believe it is the first word in the English language recorded in writing. It was recorded by Gildas in his 6th-century Latin work, *De Excidio et Conquestu Britanniae*.

In sailboats, keels often serve a hydrodynamic purpose. This means they are designed to interact with the water to improve movement. A fixed hydrodynamic keel provides the structural strength to support the boat's weight. It also acts as an underwater foil. This foil uses the boat's forward motion to generate lift. This lift counteracts the leeward force of the wind, which prevents the boat from sliding sideways.

Beyond movement, these keels act as a vital counterweight. When wind hits the sails, it creates a lateral force that causes the boat to heel, or tilt. The heavy keel offsets this heeling moment to keep the boat upright.

Some sailboats use specialized parts like centreplates or daggerboards. While these can act as counterweights, they are lighter than a full keel. Some advanced systems even use canting keels. These can swing sideways in the water to move the ballasting effect to one side. This allows the boat to maintain a more upright position while sailing.

The term keel is also linked to the Latin word *carina*. This is the origin of the term "careen," which means to clean a keel and hull. This is often done by rolling the ship on its side. An example of this history is Careening Cove, a suburb in Sydney, Australia. In the early colonial days, this area was used for the careening process. This shows how the physical needs of a ship connect to the names of places around the world.