August 11, 2022

SHIP – how was it made?

You may have wondered how a ship that weighs more than or upward of 500,000 tonnes does not sink in water, whereas a stone goes right into the water depths immediately it touches the surface, so the big question remains: How are ships made and why do they not sink? Ships are generally created in a place called a SHIPYARD. Most ships are made of materials from steel while others are made from light weight materials such as fiberglass or aluminum. Shipboard equipment varies from ship to ship depending on such factors as the ship’s era, design, area of operation, and purpose. According to briticannia, Ship construction today is a complicated compound of art and science. In the great days of sail, vessels were designed and built on the basis of practical experience; ship construction was predominantly a skill. With the rapid growth and development of the physical sciences, beginning in the early 19th century, it was inevitable that hydrokinetics (the study of fluids in motion), hydrostatics (the study of fluids at rest), and the science of materials and structures should augment the shipbuilder’s skill. The consequence of this was a rapid increase in the size, speed, commercial value, and safety of ships. In an article written by lets talk science, the principle of Archimedes’ or buoyancy is the reason why ships stay afloat in water. Archimedes’ Principle states that the force exerted on an object in a fluid is equal to the weight of fluid displaced (moved out of the way) by the object. This force is called buoyant force. The buoyant force pushes upwards against the object. Gravity exerts a downward force on the object (its weight), which is determined by the object’s mass. So if the force exerted downward on the object by gravity is less than the buoyant force, the object will float. How can this principle be applied to ships? Ships are enormous steel vessels. A ship can have a mass of hundreds of thousands of tonnes. Steel is much denser than water, so you would think that massive steel ships would sink, right? Well, think again! What helps keep ships afloat is their shape and what is inside them. Ships are not solid pieces of steel. Instead, they are mostly hollowed-out shells of steel. There are all sorts of components inside the ship. For example the ship’s engine, fuel, and cargo may be inside. But most importantly, there is air inside a ship! The air that is inside a ship is much less dense than water. That’s what keeps it floating! The average density of the total volume of the ship and everything inside of it (including the air) must be less than the same volume of water. As a ship is set in water, it pushes down and displaces an amount of water equal to its weight. The closer the total density of the ship is to the density of the same volume of water, the greater the amount of the ship that will be in the water. If the average density of the ship is ever greater than the density of water, then the ship will sink beneath the surface of the water. When a ship sinks, it is because water enters the ship. This forces out the air, making the average density of the ship greater than that of the water. One of the most famous disasters is the sinking of the RMS Titanic. The ship struck an iceberg off the south coast of Newfoundland in April of 1912. The iceberg tore open several small holes in the hull of the ship, letting water into the bow. As more water entered the ship, the air was forced out. This caused the ship to sink to the bottom of the ocean. Just like every other ship that ever sank, the Titanic ultimately went to the bottom of the ocean because of (a lack of) buoyancy! This principle has been the guiding principle ever since the beginning of the 19th century as has guided ship makers in the world to know what to look for when they construct a ship. 

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