Are Cruise Ships Dangerously Top Heavy?

Ever since the Costa Concordia disaster, questions have been raised whether modern day cruise ships are being designed more dangerously by increasing their size to pile more and more passengers aboard.

There is no question that cruise ship are getting bigger and bigger.  You need look no further than Royal Caribbean's Genesis class (Oasis of the Seas and Allure of the Seas) which each carry more than 8,000 passenger and crew members.

But it is not just that the cruise ships are getting "bigger" that may pose a danger.  Its that they are designed to be much, much taller, with the hotel structure some seventeen stories high.  The "floating Orchestra Cruise Shipcondos," as some call them, seem to be out-of-proportionally tall, perched precariously on a hull which seems incapable of safely supporting a structure towering hundreds of feet into the air. 

Yesterday, I posed the question on Twitter and facebook:  Are Cruise Ships Top Heavy?"  I received some interesting response, including this one:

Yes. Over 30 years ago the shipbuilders built a ship then put a hotel on the inside now they build a hotel/resort first and try and wrap a ship around it second.....these ships and I use this term very broadly should all be tied up at next available port and used as hotels only.

If this issue interests you, I suggest that you read an excellent article by blogger "Teddy Sheperd" entitled "Why Mega Cruise Ships Are Unsafe: Opinion."  

Mr. Sheperd explains that in the past, there was a reasonable and safe ratio between a vessel's draft (below the waterline) and air draft (above the waterline).  The cruise ships today have lost the reasonable proportions between what's below and above the waterline, making the vessels dependent on stabilizers not only to battle rough weather but to stay upright with only slight to moderate breezes. 

Take a read of Mr. Shepard's article and ask yourself whether you really want to take your family onto one of these floating sky-scrapper hotels when, God forbid, it loses power while encountering rough seas?

I do not pretend to be a naval architect.  I studied English and History at Duke.  It remains a mystery to me how jumbo jets can take off or huge ships can even float.  But you don't need to be an expert to have an opinion on this issue.  Mr. Sheperd reminds us of the old saying in boat building, "if it looks right, it is right."

Well, these cruise ships don't look right to me.  They look like condominiums ripped out of Collins Avenue on Miami Beach and placed on a barge.  They look eager to tip over.


Have an opinion whether cruise ships today are inherently unstable?  Please leave a comment below. 


Photo:  MSC's Orchestra cruise ship - draft of 7.88 metres (25.9 feet). 

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Comments (14) Read through and enter the discussion with the form at the end
Charles mathias - March 29, 2012 11:45 AM

Jim: Another concern naval architects had, some years ago, were cruise ships being designed with "open" Atriums. Saying they could not be structurly sound with an "open hole" running thru the interior of the ship (no cross support) I also question how safe is "stretching" a ship by cutting it into and adding a section.

marco carrasco - July 1, 2012 1:59 PM

bueno a desir verda me encantan mucho los cruseros y me fasinaria trabajar algun dia y perteneser ala flota y recorrer diversos paises y culturas . y adquirir nuevas experiencias de vida

Tups - July 2, 2012 11:23 PM

Modern cruise ships are very wide, and beam increases stability. Also, the superstructure is made of lightweight materials (high strength steel, aluminium) and has large open spaces while the hull is made of thicker steel and contains heavy machinery, fuel tanks etc. For that reason they have sufficient stability.

How many modern cruise ships have capsized due to stability issues?

andy - August 15, 2012 8:35 PM

Dear All.
As an ex airline jockey/pilot, the stability of these floating sky scrapers is indeed very safe, as its all in the weight and balance, the top decks whilst seemingly top heavy will be made out of a very light material rather like aircraft, and the weight inside the hull will be many times greater than the weight above sea leval, what with ballast and the engines etc. Most accidents are down to pilot error as is with ships. However, you would not get me on one of these monstrosities simply because they DO NOT LOOK SAFE, and if it don t look right, I AIN T GETTING ON IT. The designers of these things really should bear that in mind and I am very suprised so many people would even think of paying money to float on a structure that looks so unsafe, there are defernitely design problems with these things, the only one being....THEY DON T LOOK SAFE, AND THEREFORE ARE NOT PLEASING TO THE EYE AND I WOULD AS A WEIGHT AND BALANCE EXPERT NOT ADVISE TRAVEL ON ONE AS THEY SCARE THE HELL OUT OF ME.

Abraham - October 28, 2012 8:46 PM

Why are cruise ships built bigger?
Why are airliners built bigger?

The same reason that banks grow bigger and bigger.
For profit!

And till 2008, what did they tell us?
They are too big to fail!

And, what happened? They failed!

rrhoop5469 - November 19, 2012 12:15 AM

I'm going on my 4th cruise next week and you will never catch me on a mega ship. I stick to small to medium size. No more than 3,000 passengers. I usually stick with Norwegian anyways. I can barely get over how the medium sized ships stay afloat. When looking at these huge ships, all I can see is extremely rough sees or rogue waves hitting it. I'll pass. When they get rid of the med sized ships, my cruising days are over.

roger - February 14, 2013 2:34 PM

Well said jim and Andy.! A very perceptive view of things. I totally concur. As a civil Engineer and not a Naval Architect. As a person of mathematics and physics with a knowlege of volume, displacement, weight,bouyancy, pressure and an ex oilfield diver I too would Never take a cruise on one of these monstrosities. YES... If it dont look right...It aint right.

roger - February 14, 2013 2:34 PM

Well said jim and Andy.! A very perceptive view of things. I totally concur. As a civil Engineer and not a Naval Architect. As a person of mathematics and physics with a knowlege of volume, displacement, weight,bouyancy, pressure and an ex oilfield diver I too would Never take a cruise on one of these monstrosities. YES... If it dont look right...It aint right.

mike - February 19, 2014 4:54 AM

I would much rather cruise on old queen mary. A ship that tall needs as much below water if not more.

j.pardoe - April 18, 2014 9:19 AM

Look at the launching of the Lifeboats on "Concordia". When the ship developed a list of even meagre proportions, no one was able to access the lifeboats efficiently and quickly and if their was an invalid in a wheelchair then forget it! Today 100 years after "Titanic" where everybody is guaranteed a seat in a lifeboat, in effect nobody could possibly escape because of the inability to launch such lifeboats.If the captain of the Concordia had not turned into shallow water then everybody on board would have been drowned. Meanwhile, the safest ship of them all, the QE2 still lies alongside at Dubaii. If ever a ship needed to return to service it is the QE2.

Colette NIEL - April 22, 2014 6:50 PM

To often, we become arrogant... not only with one another but with Nature.... History has proven that soon or later, Nature will win! The unsinkable TITANIC... We are such fools! Who will be next? To Big, to Tall, to Heavy.
Mother Nature has a grin on her face, she is wiser than any of us and so patient. Will you be next?
History will tell and we will never learn, our arrogance is greater than all calamities together. It will be too late for the innocent victims.

tipster - July 14, 2014 10:46 AM

Well, all the opinions about looking right overlook one simple fact. If the metacentric height of the vessel is high, it is hard to tip. Plain and simple. Does not mean it can't tip, but that the forces required to make it tip are greater. The higher the metacentric height, the shorter the roll period, and typically the less comfortable it is for passengers, but the harder it is to tip that ship over. So, the opinions on how it looks mean nothing to the physical forces acting on that ship. Cruise ships tend to be very wide, increasing the metacentric height and the length of the righting arm. Because of the massive equipment in lower decks, you get a nice configuration where the center of buoyancy is below the center of gravity and a nice tall metacenter. [Ships that have their metacenter and center of buoyancy at the same point are called submarines.] Tear apart the hull, however, and stability changes become rapid, dramatic and difficult to predict, depending on location and size of the hull tear. Once the center of buoyancy drifts over the center of gravity, it does not matter how tall or short your ship is, it just became a sinking vessel.

Moschops - September 7, 2014 9:24 AM

Let's look at the numbers. If these things are unsafe, lots and lots of them would spend their time tipping over and capsizing. I look back through the news, and that turns out to very rarely happen, and every case I've found where it does happen has involved some other mistake first (such as running aground, or having the car door break off).

If they were unsafe, they would be falling over all the time. They don't.

Russell f lowe - February 25, 2015 1:06 AM


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