How do cruise ships stay afloat?

While the cruise industry continues to see a flow of contemporary vessels, there is one significant factor that remains synonymous across all ships yet is often overlooked. Lines such as Royal Caribbean, MSC Cruises, NCL and many more construct increasingly larger cruise ships – each of which operates just as smoothly as the predecessors before it. This begs the question as to how a ship manages to stay afloat – especially when you consider the gross tonnage of the world’s largest cruise ship, Harmony of the Seas, is 227,000.

The short answer comes down to density and buoyancy. The weight and shape of the ship, when pressed against the surface of the ocean, has to result in the displacement of the same amount of water as the force being exerted upon it In order to stay afloat. In other words, the heavier the ship is, the more water it has to move – otherwise, the vessel will become submerged. This is where the density of the vessel becomes a significant factor – much like how an object such as a rock will sink, while a beach ball will float.

How can this principle be applied to the world of cruising? Lightweight and sturdy materials used in the ship construction play a vital role in ensuring sufficient water is displaced. The hull is often constructed to be very wide and will extend deep beneath the surface of the sea. A V-shaped hull is often applied to cruise ships, enabling them to skirt the waves and significantly reduce the amount of friction – thus being able to travel at a good speed.

It is also worth noting that significant time and effort goes into the interior design of the vessel, ensuring that – no matter how many restaurants, bars, amenities, etc. that there may be – there is still plenty of open space. It is this open space that will ensure each cruise ship remains considerably less dense than the average density of the ocean. This is the basic idea of Archimedes’ Principle, whereby an object can float on water when the weight of water displaced is equal to the weight of the object.

Different ships, however, are designed differently to suit a specific purpose. Icebreaker ships that traverse the Arctic and Antarctic regions are fitted with rounded hulls that are capable of smoothly cutting through ice with a thickness of three metres. Freight ships have a hull that is more u-shaped than V-shaped, which offers vital stability for carrying such a significant amount of weight. However, this stability compromises the speed at which the vessel can travel, due to an increased amount of friction.


Some cruisers believe that cruise lines are getting carried away with the sheer size of their vessels. Despite announcements of glittering amenities and modern features, the fundamental factor of keeping the ship afloat remains a more important than ever before. Cruise ships of the 21st century are being built at some of the world’s most renowned shipyards – each of which has an expansive portfolio.

If you love cruising and are seeking a new and exciting business opportunity, you may be interested in learning more about the opportunity available with GoCruise. By running your own franchise business, you will be able to build a rapport with people in your local community and start earning competitive rates of commission.

For more information, contact us via the freephone number above or complete the online application form.

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