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 (39) 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


tom terrific - March 17, 2015 12:42 AM

Don't know how safe in a storm but I'll say this: with the numbers of poorly mobile passengers aboard, in wheelchairs, etc, we'll never get to lifeboats as passageways will be clogged.

john Aldersley - March 19, 2015 6:21 AM

I'm currently on MSC Orchestra on its grand voyage to Australia and back. I agree to the caual observer it looks impossibly top heavy. But the eyes are deceiving. The ship has encountered the edge of a cyclone and rough seas and as a passenger it has hardly swayed. As a former yachtie I cannot believe how well it has handled the swells and wins. It doesn't even slow down, 20 knots in calm or rough. The stabiliser technology must be quite something. My house vibrates more in a 150 knot breeze.

moon zirky - May 3, 2015 5:06 PM

All it would take is one rouge wave and thousands would drown'

Robert Norminton - June 6, 2015 1:20 PM

As an ex-mechanical engineer with some small experience of ships, I say Tipster is correct in his discussion of the influence of metacentric heights. Nevertheless, there are recognized dockside stability tests to see how slowly or quickly a ship rights itself from a designated amount of heel. A dangerous ship is called "tender". Are these tests mandatory, or can they be demonstrated merely by someone's calculations? Is the calculated stability dependent on working stabilizers? (My sister was on a cruise ship in a Pacific typhoon where these failed. Everyone was so seasick that they couldn't have roused themselves for rescue, had it become necessary.) And what about wind loading on those immense topside elevation areas, which, if large enough, will capsize any vessel that is not so "stiff" in stability tests that it wouldn't be comfortable to sail on. I'm not convinced by "all-is-well" arguments.

old sea dog - September 25, 2015 6:20 AM

Tipster & Robert above have it right. However, I went to see BRITANNIA this week at Caragena. 143,730grt, 11,793tdw 27'03" draught, 15 decks, 4,324 Pax, 1,398 crew. It looks 27 feet in the water 130 feet in the air; apearance apparently top heavy but upright so it can't be. 11,793dwt is the amount of "cargo" fuel, lubes, stores, water including that in 4 swimming pools all with free surface. The "cargo" being 5,722 humans with their effects would possibly equate to 600 tons - if they can all fit on the top deck that woul give a moment of 78,000 foot/tons above waterline. Can anyone imagine a total disaster at sea, only emergency lighting, possible smoke or fire, possible flooding, no lifts, plenty of panic; let us hope it nver happens. I have tried to find out the stability data for this ship but without result. anybody out there have it?

Harrison2253 - February 10, 2016 6:27 PM

Under the right conditions of high winds and rolling sea's I can see one of these things rotating over on its side very easily. Just a matter of time before it happens then they won't be able to get anyone on one of those things.

Andrew Eppink - February 16, 2016 2:55 AM

Cruise ships aren't top heavy tho they certainly look it and have large sail areas, which can cause problems. Above the hull the hotel structure is largely empty space - rooms of various sizes and relatively light. Like an egg carton. The heavy machinery is down low in the hull producing a low mass center and consequent stability. These vessels are designed by competent and experienced Naval Architects and Marine Engineers, and, while problems can and do happen, they're safe vessels. They'd never make it thru the various classification societies if they weren't.

Ken St. Amour - February 22, 2016 9:40 AM

All things considered, these ships do look top heavy but the statistics don't indicate that they capsize or just turn over on their side. But I have to agree, these giants of the Sea look a bit out of place. But tell that to the hundreds of thousands of people that love taking vacations on board. The Costa Concordia didn't run aground because it was top heavy.

KNUT HANSÉN - May 19, 2016 8:01 PM




KNUT HANSÉN - May 20, 2016 9:25 AM








Steve J - May 21, 2016 11:06 AM

I like the way so many have so much faith in the various institutuions that these vessels are "safe".
In her day, Titanic was of course "unsinkable".
Agreed, the Costa Concordia did not roll over....but it didn't take much to make it do so, did it? And had it not been for the grounding she would have no doubt have gone the full 90 degs.
And yes, I agree, it was down to human error:
Exactly same kind of humans as found on cruise ships everywhere.
Remember too, the drafts of these vessels has been pared to the minimum, in order that they can visit exotic, smaller ports.
Sorry, but my conclusion is that they are a disaster looking for somewhere to happen.
And I won't be on one when it does.

john j ferrera - May 23, 2016 8:57 AM

I agree with if it doesn't look right; it isn't. Gazing upon these floating condos, no need for me to conjure up another description, I immediately sensed danger and thought of Shelly Winters and Ernest Borgnine.

Engineer - January 12, 2017 5:43 PM

Counselor, you have posed a question for comment about how 'safe' people think these mega-ships are. This is certainly a 'fun' question with a lot of 'You'll never catch me on one of those' answers. However, in court, the only opinion that would hold water would be from an Engineer. The propensity to tip or tilt is strictly a matter of Engineering; not opinion. It has to do with the relationship between the center of buoyancy and the center of gravity with additional consideration for the torque associated with wind loading. These structures were designed by ship building engineers -I'm confident they are perfectly safe. Exception: Punch a huge hole in the side below the waterline (Titanic). One opinion that you may draw when reading this: "Engineers are boring." Perhaps true, but they are good at designing safe ships.

Gregory - January 15, 2017 7:47 PM

I was kn Norwegian Escape last week during a moderate storm and this tallest of all cruise ships swayed, rocked and rolled like there was no tomorrow. This was my 10th cruise so far and the 1st where i experienced this level of constant rolling to its sides by gusting winds. Terrible. Everyone was sea sick.

Cory - January 20, 2017 6:18 AM

Not 100% unsafe, but does unfortunately increase the risk. If you would compare the titanic's hull percentage below the waterline, it exceeds that of most modern cruise ships. Ships that stand higher above the water result in a HIGH centre of gravity, that's scientific common sense. The roll of the vessel is slower and less frequent yes, but buoyancy-related it is more dangerous. The reason for minimizing hull percentage below the waterline is to make sailing more comfortable in bad sea conditions, hence the slower and less frequent roll. A model of the titanic and a modern liner was tested at maritime engineering faculties at various universities. The ship with the lowest centre of gravity, titanic, rolled more, but never came close to capsizing. The cruise liner on the other hand, because of not having enough "ship" below the waterline, capsized. The higher the ship, the higher the centre of gravity, and the higher the centre of gravity, the greater the risk of a heavy roll that could capsize the ship.

Tom Detweiler - February 9, 2017 12:21 AM

I am a US Navy sailor, served aboard a Gearing Fram-2 destroyer. That ship was about 350'L with a draft of under 15'. However it had all its fuel tanks, water tanks, ballast/coolingwater tanks, below the main deck and most, below the water line, and a good heavy steel keel. Also, only one main deck that went full length. The new cruise ships give me the willies-- and I visualize that scene in "2012" with the monster wave flipping one over. I have been on a couple NCL cruise ships but their draft/air draft ratio was sensible, then (80s).
Now, no way! There is a floating hotel sitting on top of a ship-shaped, big beamed BARGE. And how many other people do you, as a paying customer, want on your cruise ship, anyway? No mega ships for this sailor!

Angus - March 7, 2017 4:49 AM

There's a difference between bad taste and bad technology. These so-called ships are revolting to look at but it has to be admitted that they have had no major disasters (except Concordia, which was the crew's fault). There was an issue with lifeboats which could be the fault of the wide beam: that could do with being properly investigated.
No! I wouldn't set foot on one but I don't wish them any harm. Like someone else wrote, they are big business money-making machines - just like banks and other financial monsters (not you, Rupert M., Donald T., Mark Z. and others...)

Lobster Fisherman - April 2, 2017 9:29 AM

One fact not elaborated on is the hull width to height ratio.
The Allure is 154ft at the waterline and 236ft above the waterline. A ratio of .65. For an example the older smaller Sun Princess was 105ft at the waterline and 185ft high. A ratio of .56. Which gives the Allure a big advantage in stability.
But remember; the center of gravity is MUCH more important than height, it is just not as easy to see.
Additionally (I am commercial fisherman) I will say"the bigger the boat the smaller the effect of the wave."
I have cruised on the Sun Princess and on the Mariner of the Seas (127ft waterline/207ft high) and found the motion (in similar sea conditions) remarkably less on the bigger ship.

old sea dog - June 6, 2017 3:45 AM

Some very interesting comments. Merchant ship stability is an extremely interesting subject & has many different aspects. I sailed with one company which had 8 similar sisters which had no bilge keels but were fitted with McMullen passive flume tanks. This, for alleviating damage to fruit cargoes, did not reduce the amplitude of the roll but did give a greater roll period. The allowed metacentric height was extremely low but the ships sailed safely for many years & there were no incidents reported. In another ship, a roro vehicle & newsprint carrier which I joined as mate & which had an active flume tank, I requested the master that I operate the flumes. He refused on the basis that it would reduce the dynamic stability of the ship & that the flumes had never been operated since building 2 years earlier. Result: we ran into a January storm in the North Atlantic with significant cargo damage. I left that ship (& company) as soon as I could & the ship was eventually sold to the US Navy; it would be interesting to know how they operated her.

I have one question about cruise ships & ensigns. A couple of weeks ago I photographed P&O's ROYAL PRINCESS sailing from Cartagena (Spain). She is registered at Hamilton, Bermuda & was flying the red ensign. All other Bermuda registered ships I see fly the Bermuda national flag which is a red ensign with a device in the fly. Which flag is the correct one?

Zach Nameless - June 12, 2017 2:00 PM

They're safe, and they aren't top heavy -- they only look top heavy.

It's simple math. If the CoG was above the water line in any situation, then any perturbation would capsize the ship. Wind can't blow them over, waves can't topple them, because the CoG is always below the waterline.

Simple proof: fill a tall cup with a thick glass bottom 1/4 of the way with water. That simulates the mass distribution in a cruise ship. Now put it in a sink full of water and see how far you have to push it over before it won't right itself. (Hint: nearly 90 degrees)

They're safe from rolling over. Trust math and science.

Ed Manley - September 10, 2017 9:42 AM

Funny what people choose to worry about. Every one of you decrying the safety of these ships and swearing never to sail on one get in your car and drive every day. It's the most dangerous thing you can do, and yet you worry about it not at all!
Reality, y'all. Get some!

T Jones - September 13, 2017 8:39 PM

Never be on one of these tall cruise liners in the Gulf of Alaska in an ice storm. They would be so top heavy they would roll over in high winds. You don't see them cruising Lake Superior either. Edmond Fitzsgerald is a current example of a 1000' vessel of latest design breaking in two and sinking with all hands on board lost at sea in minutes.

K Hodgson - November 13, 2017 9:08 AM

I don't like these "ships" because they are just floating mega-hotels and in any possible incident with over 6,000 passengers you would have people"problems". I sailed across the Pacific on the Oronsay in 1959, Southern Cross, Canberra later and hand built and sailed my own boat out of New Bedford, MA in the old days. The old liners like the P&O liners were a different design concept and older technology. Oronsay was ice classed and had a much heavier steel hull and going through the Tasman Sea easily handled 40-50 ft. plus rollers but it did pitch and roll a bit being a narrower design like the SS United States-a giant destroyer actually slim looking from the bow. I think these ships are ok for what they mostly encounter but not the Tasman Sea in bad weather. They are tourist barges with casinos going to tourist trap islands fleecing as many folks as possible for Carnival Corporation. They're not liners capable of handling any sea condition with freight and passengers. Liners couldn't compete on cost with jets, fuel costs, or containerized shipping and were scrapped but the high point of my life was sailing on them. The Edmond Fitzgerald was a laker not a "Saltie" and in heavy weather you have a very long, old, poorly maintained "flat" bottomed boat with leaky hatch seals hitting seas like the North Atlantic in November. Most incidents are due to poor decisions based on time and money concerns-including the Andria Gale in the "Perfect Storm". The El Faro sinking is a good example. Captain and company pressure resulted in his decision to sail into the Eye of a major hurricane but the company doesn't care they collect insurance and get a new boat. You might include the sinking of the Titanic in this category also. For what these "things" are designed for they have a fairly good safety record, I just don't like being packed with thousands of idiots at sea on a giant ugly barge. You can go to Vegas for that type of experience.

Hines - January 8, 2018 11:30 AM

Also they would make a likely terrorist target; all those people trapped in one place with no where to go but down.

Timmah - March 16, 2018 3:48 AM

Modern cruise ships look top heavy but have far more intact stability than it looks like they have. All the heavy machinery is down low, and the superstructure higher up is built of strong but lighter weight materials. The center of gravity is low enough and the ship wide enough that as it lists over, the center of buoyancy will counteract the listing force and right the ship. But the key to all this is the word "intact". You damage the hull, like what happened to Costa Concordia, and you have a whole new set of stability rules.

I'm a Naval Architect and made a career out of dealing with ship stability. But all that said, I wouldn't want to take a vacation on these new gigantic cruise ships. They're just too big, too many people, I like vacations to be peaceful and relaxing and I can't imagine such a crowded ship to be peaceful.

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