How can cruises stay afloat for years?

With the development of technologies and engines, many things became possible and available for ordinary people all over the world. While we all enjoy the evolution of technologies and the new possibilities that we are offered, some very natural questions usually awake. Those questions mostly arise when we see something acting against the physics law.

The pure breach of the physics law is the huge machines flying high in the sky and carrying hundreds of people on board. Several centuries ago, this was something that people would never believe in, and seeing flying objects in the sky would indicate metaphysical abilities rather than engines. The same happens with the huge ships and cruises.

It should be very simple. When we put a heavy object into the water it sinks. We put a coin in the water, it sinks. If we jump into the water, without knowing how to swim, we will sink as well. On the other hand, the huge ships and cruises that are hundreds of meters long and several thousands of tonnes can keep afloat for very long.

Paradox
Going on cruise ships has become very popular especially for the past several years. This is no longer the activity for only rich people. Ordinary people can afford to cruise as well. According to the statistics, over 25 million people take cruises annually. This is not a small number and the number is ever increasing.

It is also a huge paradox, that one of the saddest events in history and one of the biggest catastrophes has contributed a lot to the cruise industry in the first place. We all are familiar with the world’s most popular cruise ship Titanic. If you do not know history, you should at least have watched the movie. The story of Titanic is very sad and unfortunate as many people have died due to the accident of the iceberg. Though, in the end it became one of the best-known historical events and one of the biggest motivations to continue the further evolution of the cruise industry.

While seeing a huge ship on the float, you will definitely have the question, how this thing can stay afloat and does not sink into the water. Well, you are not the only one asking that question. Back in 2013, princess Kate and Prince William were visiting the Royal Princess cruise. The Duchess was pregnant with prince Gorge at that time, but anyways they had to spend one week on that huge cruise ship. I don’t know why they were not thinking of being seasick, but anyway, the answer to her question exists and this is the following.

Against physics
While cruises are affordable for most of the people and there are no more social class distinctions, just like with Jack and Kate, everyone can take a cruise even for a weekend. Some of them are very luxurious, with a very fancy restaurant, clubs, bars, swimming pools, more swimming pools and there even are some of the best online casinos for VIP players here. Luxury casinos are actually one of the most important aspects of the huge cruise vessels. This is not only for the entertainment purpose though. Usually, luxury and high-roller casinos play quite a significant role in the business. Many people choose specific cruises relying on the casinos. Cruises are international and many people from all over the world are the guests. While in some countries gambling is illegal, international waters is where specific regulations and laws do not comply. Basically, while being on the cruise, the guests have no restrictions and limits on gambling, meaning that they can enjoy their whole trip at its best.

The cruises can be huge. Sometimes they may exceed the length of several hundred meters and this is not something very unusual. They carry hundreds of people, their luggage, equipment, tables, beds, showers, water, and their engines. Overall, the weight of the cruise can be more than several thousands of tonnes. This is a huge number, especially comparing it to the tiny coin, which immediately thinks into the water once you throw it.

Though, here comes the other questions, have you ever thought, how did the old man put the latter into the bottle and it never sunk, but opposite the sea carried the bottle. Or have you thought about a volleyball ball? It is very light, but even if it gets into the water it never sinks, it floats. Have you thought of the person, who is lying on his back and floating on the water? Why does this happen and if physics applies to water generally, why are there such big exceptions?

There is not much of a secret, but an air. The air is the highest component that can be found in any object and exactly the air makes the other objects lighter and gives them the ability to transfer to something that acts against certain laws. To be more precise, I will try to explain the engine and the whole structure of the cruise.

Its physics, there’s no escape
The size of the ship is calculated on its tonnage. Though, this is a measure of volume rather than weight instead. This means that the tonnage is defined by the ship’s enclosed internal space. The ship’s tonnage is measured by the amount of water it displays.

First of all, it should be mentioned that only 10% of the whole ship is placed underwater. Of course, the heaviest part of the whole ship, which is the engine, is located exactly within that 10 %. Despite the seemingly unfeasible height relative to the volume below the waterline, the center of gravity is kept low because the heaviest equipment is located below deck. In the same place, there are tanks with waste and fuel as well as with drinking water. There are ballast tanks, containing water that can be pumped from one end of the ship to the other and from port to starboard in order to maintain the balance and the stability of the whole corpus.

The whole physics comes now. A cruise ship displaces an amount of water equivalent to its own mass. The pressure of the sea pushed up against the vessel’s hull to counter the downward force of the ship’s mass. Unlike air, water can not be compressed so the combined force creates the buoyancy. This principle was first discovered by Archimedes, 2300 years ago.

The water a cruise ship displaces becomes the waved and washed as it moves along. A rounded U-shaped hull is preferable for creating the buoyancy. Some ships have flat bottoms. They can stay afloat for very long as well, the only difference is that it will be uncomfortable for them to move in heavy seas.

While the main principle of the cruise ship is staying afloat, the whole core should be assisting it to comply with the principle. The U-shape is essential for resisting obstacles such as rocks, sandbanks, concrete piers as well as icebergs. Inside, a series of separate compartments with automatic watertight doors prevent the hull filling completely with water. On the Titanic, those compartments did not reach high enough and water overflowed from one to another.

There were some other unfortunate cases with cruise ships as well. Some of them were caused by the engine malfunction, while others by the wrong decisions and malfunction of the captain. One of such cases is Costa Concordia. The fate of the ship and 33 people on board was defined by the decision of the captain to sail very close to the rocks. At this time, several compartments broke at once and the captain’s effort to turn the ship caused the ship to tilt with the unfortunate consequence.

Another very important aim of the watertight compartments is the prevention of the fire on board. In the modern world, there should be less fear regarding the iceberg, as spreading the fire sounds way more realistic.

Conclusion
While the ships and the cruises have become very popular and many people visit them annually, certain regulations and changes, both on the governmental level and engine levels have been implemented in order to make the trips safer and more comfortable. So the next time you step onboard you should know why the ship does not think and stays afloat. And, if you are afraid of sailing just like I am, remember that the chances of the catastrophe or the ship hitting the iceberg are less than the chances of you owning your own yacht in the next five years’ time.