Ah! A majestic Snow White cruise ship looks like a piece of art. It’s a city in itself with cafes, stores, swimming pools, gyms and a water park. Everything from its impressive size to the number of passengers on board leaves unprepared observers speechless.
The biggest mystery for some people is how does that big guy stay afloat and avoid Keeling over? Well, imagine something as large as the Empire State Building in length and 10 giraffes both in width and in height. The weight of the biggest cruise ships can equal the weight of 2000 Blue Whales piled on top of each other. One of the world’s largest cruise ship can transport almost 7000 passengers and more than 2000 crew members.
But even if most of these people gather on one side, such huge cruise ships won’t tip over. Well, it doesn’t prevent people from worrying that at some unlucky moment, such a jumbo ship can flip over. What these people don’t know is that a cruise ship can roll to almost 60 degrees before it’s in danger of tipping over. Plus, cruise ships are built to withstand 50 foot (15 metres) waves. But in reality such huge waves are a rarity, and a typical ship is unlikely to come across one of those during his career.
Cruise ships are surprisingly well prepared for all the bad weather one can expect out at sea. They’re designed to handle even severe storms during the hurricane season. Before construction, the naval architects make a ship scale model and put it through all kinds of extreme weather simulations. This way they check how the future full size vessel will react in any given situation.
Coming back to our question that how cruise ships manage to stay upright and afloat in almost any weather? Do they probably have a massive and heavy underwater part that helps them to keep the balance? Not at all. Cruise ships have narrow and wide bottom surfaces. Usually no more than 30 feet (9.1 metres) of a vessel sits under the water, which is only about 10% of the ship’s overall height. These vessels are massive, and incredibly heavy.
Keep in mind that a cruise ship carries not only its own way, but also the weight of at least several thousand passengers and crew members, all their luggage, food, furniture, swimming pools filled with water elevators and a whole lot of entertainment. But even loaded with all this hefty cargo, a vessel is still filled with air, which makes it buoyant-capable of floating.
When you place some object, be it a piece of wood or a huge cruise ship in the water, whether it sinks or floats will depend on its buoyancy.
Buoyancy is tightly linked with how dense the object is. If it’s denser than water, like a stone, it will sink otherwise it will stay on the surface. Now one more thing, if you put a floating object on the surface of the water, it will make the water push upward against it. This pressure is what keeps the object from sinking. The only difference between a cruise ship and a piece of wood is that the vessel sits in the water way, way lower than the wood because of its immense weight.
It doesn’t explain why cruise ships don’t tip over, though. If you look at a cruise ship’s hull, you’ll notice its unusual shape. It’s wide and rounded. This helps the vessel to move smoothly and with minimal drag. That’s a force which slows a ship down. Round edges also increase the ship stability, preventing the vessel from swaying and rocking and passengers- from feeling seasick.
Even though a cruise ship towers above the surface, its centre of gravity is far below the waterline. The heaviest equipment, engines, tanks with fuel drinking water and waste, all of this is at the very bottom of the ship on the lowest decks. And that’s not all. Among these bulky tanks and containers, there’s something crucial for the ship’s balance, ballast tanks. They contain water that can be pumped from one side of the ship or the other. In case of an emergency or rough seas, it helps to keep the ship balanced, counter the waves and reduce rocking. A large cruise ship usually has several ballast tanks.
So buoyancy, low centre of gravity, and ballast keep a cruise ship stable, but there is one natural phenomenon that can still put this vessel at risk. And it’s not wind. Surprisingly, experts say that no wind can be strong enough to cause a ship to turn over. The danger is rogue waves. These are the waves that can be twice as tall as others and come from any direction. They appear out of nowhere, and no one can predict when and where they will pop up. It’s a good thing Rogue waves are extremely rare, and chances that a cruise ship will meet one are really low.
Sometimes, a cruise ship doesn’t manage to dodge a storm and has to force its way through the waves. If that happens, the most important thing is to keep the ship’s front (the bow) pointed into the waves. For onlookers, the view will be terrifying, giant waves rising right in front of the bow. But seamen know that only this way the ship can plow through the waves safely.
A wave crashing against the side of the ship is way more dangerous because they can easily turn the vessel over. Cruise ships are equipped with special stabilisers that prevent them from tilting to one side too much, but they don’t help with pitching- front to back movements. For this purpose. cruise ships have long and narrow bows that help them cut through the waves more effectively. Combined, stabilisers and long bows help cruise ships to weather even powerful storms.
Here is an interesting video on this subject: