How much larger can ships get?

[BoiiMcFly]

With Harmony of the Seas being the current largest vessel, many say that it's only a matter of 3-5 years before they surpass it. Do you think cruise ships will ever plateau at a certain size, or we will constantly find ways to make them bigger?

 

I believe we will always look for ways to make ships bigger, and eventually they will be floating cities with streets and possible permanent housing. I am thinking way in the future here :D

[Aquahound]

I believe we will always look for ways to make ships bigger, and eventually they will be floating cities with streets and possible permanent housing. I am thinking way in the future here :D

 

Though not bigger and not with streets, a cruise ship already exists with permanent residents. Its called The World.

[BoiiMcFly]

Though not bigger and not with streets, a cruise ship already exists with permanent residents. Its called The World.

 

Yes it made me think of The World. How does it work aboard that ship? Is it like timeshares?

[Essiesmom]

I believe is is like condos and some treat them as timeshares...EM

[BlueRiband]

The larger a ship gets the more limited its possible itineraries. It cannot enter ports where bridges are too low or the harbor is too shallow. That, and many older cruise terminals were built in the mid-twentieth century. They don't have the facilities to adequately service large ships or handle the volume of passengers. Passengers gripe when getting off the ship to go ashore or to disembark is delayed.

 

A good example for all of the above is QM2. Her funnel is much shorter than the architect wanted because she had to squeeze under the Verrazzano Narrows Bridge into NY. Her ocean draft of 33ft means that she needs deeper harbors than most cruise ships. And a turn around at the Manhattan piers delays sail away as they do not have the modern service facilities of the much newer Brooklyn pier.

[chengkp75]

Again, I will ask what your criteria is for "largest". While Harmony is the largest cruise ship, it doesn't really enter the top 10 of largest ships even in terms of Gross Tonnage. The largest ship in terms of Gross Tonnage is the Crane Vessel "Pioneering Spirit", which comes in at a whopping 403,000 Gross Tons.

 

Now, the largest ship in terms of "deadweight tonnage", or the amount of cargo weight it can carry, was the Seawise Giant (among other names) at 564,000 deadweight tons. Now, considering that the Harmony actually weighs about 100,000 tons (displacement), that means that if you put the Harmony and her two sisters into a "ship crusher", the Seawise Giant could load all three of them, along with a couple of the Quantum class ships.

 

The Seawise Giant also dwarfed the Harmony in terms of displacement (actual weight of the ship), coming in at a whopping 657,000 tons, compared to the 100,000 tons of Harmony and the largest aircraft carriers afloat today.

 

As to how large they can get? Theoretically anything is possible. The "Freedom Ship" project is much like what you describe as a floating city, but it has been a design dream for a couple of decades, and no one is willing to risk a vast amount of capital on an unproven hull concept. Remember, the horsepower required to move a given weight through the water, is in an exponential relationship to the weight. And the fuel required to move that weight through the water is also exponential to the speed. So, while there are economies of scale in larger cruise ships, at some point, the cost of energy to move it overcomes the economies.

 

We are currently pushing the boundaries of lifesaving equipment that is proven capable of evacuating large numbers of non-trained personnel from ships with the existing ships. I think the flag states and class societies will take a long look at any new lifesaving equipment introduced to increase passenger ship size beyond small increments to what is built today.

 

The final obstacle to larger cruise ships is port infrastructure. The larger the ship, the fewer ports capable of handling the ship.

[navybankerteacher]

The larger the ship, the more varied the activities and options - and the more you will be able to do everything which is possible at a land resort: so why bother making it float - ultimately, increasing the size of ships will reduce the point in building, and sailing on, them.

[BoiiMcFly]

The larger the ship, the more varied the activities and options - and the more you will be able to do everything which is possible at a land resort: so why bother making it float - ultimately, increasing the size of ships will reduce the point in building, and sailing on, them.

 

But I feel like that's not stopping people from cruising on them. Most of the things you can do on the Harmony can be done on land as well, but people still choose to sail on it.

[BoiiMcFly]

Again, I will ask what your criteria is for "largest". While Harmony is the largest cruise ship, it doesn't really enter the top 10 of largest ships even in terms of Gross Tonnage. The largest ship in terms of Gross Tonnage is the Crane Vessel "Pioneering Spirit", which comes in at a whopping 403,000 Gross Tons.

 

Now, the largest ship in terms of "deadweight tonnage", or the amount of cargo weight it can carry, was the Seawise Giant (among other names) at 564,000 deadweight tons. Now, considering that the Harmony actually weighs about 100,000 tons (displacement), that means that if you put the Harmony and her two sisters into a "ship crusher", the Seawise Giant could load all three of them, along with a couple of the Quantum class ships.

 

The Seawise Giant also dwarfed the Harmony in terms of displacement (actual weight of the ship), coming in at a whopping 657,000 tons, compared to the 100,000 tons of Harmony and the largest aircraft carriers afloat today.

 

As to how large they can get? Theoretically anything is possible. The "Freedom Ship" project is much like what you describe as a floating city, but it has been a design dream for a couple of decades, and no one is willing to risk a vast amount of capital on an unproven hull concept. Remember, the horsepower required to move a given weight through the water, is in an exponential relationship to the weight. And the fuel required to move that weight through the water is also exponential to the speed. So, while there are economies of scale in larger cruise ships, at some point, the cost of energy to move it overcomes the economies.

 

We are currently pushing the boundaries of lifesaving equipment that is proven capable of evacuating large numbers of non-trained personnel from ships with the existing ships. I think the flag states and class societies will take a long look at any new lifesaving equipment introduced to increase passenger ship size beyond small increments to what is built today.

 

The final obstacle to larger cruise ships is port infrastructure. The larger the ship, the fewer ports capable of handling the ship.

 

Thanks, and my bad should have been more specific, I was referring strictly to cruise ships. Also, I am a little confused about the tonnage of a ship vs displacement. Do you mind explaining the difference? Which is the actual weight of the ship? Because it says the Harmony weighs 220,963 tons, with a displacement of approx 12,000. I am confused about the actual weight of the ship now lol.

[sparks1093]

But I feel like that's not stopping people from cruising on them. Most of the things you can do on the Harmony can be done on land as well, but people still choose to sail on it.

 

Yes, there are many people that like those bigger ships. I will take a mid-sized ship any day of the week. I fear that eventually you'll be able to embark in NY and walk to the other end of the ship, disembarking in London, without ever leaving port.;)

[BoiiMcFly]

Yes, there are many people that like those bigger ships. I will take a mid-sized ship any day of the week. I fear that eventually you'll be able to embark in NY and walk to the other end of the ship, disembarking in London, without ever leaving port.;)

 

Lmao who knows it could actually happen. Technology is advancing so fast these days.

[TheOldBear]

Thanks, and my bad should have been more specific, I was referring strictly to cruise ships. Also, I am a little confused about the tonnage of a ship vs displacement. Do you mind explaining the difference? Which is the actual weight of the ship? Because it says the Harmony weighs 220,963 tons, with a displacement of approx 12,000. I am confused about the actual weight of the ship now lol.

 

There are three tonnage numbers - and they are at best loosely related.

 

1. Gross Tonnage is a measure of the enclosed space within the ship's hull and superstructure. 100 cubic feet is one 'ton' for this measurement.
    
   
2. Displacement Tonnage is a measure of how much the ship weighs - what you would measure if you picked up the ship and put it on a big scale. [Or the volume of water 'displaced' from a full pool if you carefully lowered the ship into the pool]
    
   
3. Deadweight Tonnage is how much cargo you can fill an empty ship with and still safely sail.
   

 

Divide the Gross Tonnage figure by the number of passengers, and you get a crude measure of how much elbow room a typical passenger will have.

[chengkp75]

Thanks, and my bad should have been more specific, I was referring strictly to cruise ships. Also, I am a little confused about the tonnage of a ship vs displacement. Do you mind explaining the difference? Which is the actual weight of the ship? Because it says the Harmony weighs 220,963 tons, with a displacement of approx 12,000. I am confused about the actual weight of the ship now lol.

 

I'm assuming you are referencing Wiki, but mistyped the displacement, which should be 120,000 metric tons. That is how much the ship actually weighs. Many sources mistakenly cite Gross Tonnage as "weight", when it isn't.

 

In your other thread on Harmony, I explain the difference between Gross Tonnage and displacement.

[BoiiMcFly]

I'm assuming you are referencing Wiki, but mistyped the displacement, which should be 120,000 metric tons. That is how much the ship actually weighs. Many sources mistakenly cite Gross Tonnage as "weight", when it isn't.

 

In your other thread on Harmony, I explain the difference between Gross Tonnage and displacement.

 

Gracias again, I believe I understand now. So a fully loaded ship represents the Gross tonnage, whereas the displacement is the actual weight of the ship without any cargo?

Edited January 26, 2017 by BoiiMcFly

[Sequim88]

Its called The World.

 

Although it is not particularly large or different looking I plan to try to watching it arrive in Seattle on Sunday July 2nd at Pier 66. Not sure how long it is in town but when it leaves I might head down to a local beach to watch it cruise up Puget Sound. I think when it ports somewhere it sticks around for a while so the residents can explore a destination.

 

As for "city" ships - while not strictly speaking a ship I did see an article once about large (very large) octagon shaped floating platforms that could bolt together with prefab streets and building foundations for modular construction. In theory giving wave flexibility and tide/flood protection. Although no propulsion is involved.

 

As far as floating roads... the New Evergreen Point Floating Bridge in Seattle weighs (displaces?) something like 360,000 tons. You can do a lot with a lot of hollow concrete - just don't try to move it. ;) Longest and widest floating bridge in world.

 

New bridge (light) next to old bridge (dark) that is now gone.

Edited January 26, 2017 by Sequim88

[chengkp75]

Gracias again, I believe I understand now. So a fully loaded ship represents the Gross tonnage, whereas the displacement is the actual weight of the ship without any cargo?

 

The displacement of a ship varies with how much cargo (passengers), fuel, water, supplies, etc. are onboard at any time. It represents the actual weight of the ship and everything in it.

 

Again, Gross Tonnage has absolutely nothing to do with weight. It measures volume, of the entire ship, not just the volume of water that is displaced. Since a ship is basically empty volume, the Gross Tonnage is a greater volume than the volume of water displaced.

 

Here's a quick discussion about the various "tonnages":

 

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=0ahUKEwiduYKF2uDRAhVX3mMKHcMVC9wQFggwMAM&url=http%3A%2F%2Fwww.themaritimesite.com%2Fa-guide-to-understanding-ship-weight-and-tonnage-measurements%2F&usg=AFQjCNEG53uFSUhk3-jfhSWtJvWedz22FA

 

Just note that today's "gross tonnage" is different from the "gross registered tonnage" discussed in the article. GRT is defined as 100 cu. ft., while GT is modified from the no longer used GRT.

[Pyrate13]

I can recall reading an article many years ago about a design for a ship that was a mile long. It had a runway on the top deck as well as living spaces, shops, schools, recreation areas, etc. Pretty much everything you would find in a modern city.

 

As for walking from NY to London, I also recall reading about a design for a "floating" tunnel under the Atlantic that would go from NY to England. It would utilize a train type care similar to maglev that could reach super high speeds and make the trip in less then one hour.

 

In both instances the cost factor was the main stumbling block. Both sound very far fetched but with the speed of technology expansion today, who knows what our future generations might find normal. I for one, would love the opportunity to come back and see.:D

 

"To infinity and beyond!"

Edited January 26, 2017 by Pyrate13

[LondonTowner]

Those huge ships are not for me.

 

Well, we do at least have the Eurostar which goes under the Channel Tunnel. London to Paris, city centre to city centre in 3 hours. Not exactly London to NYC, but it's a start.

[cb at sea]

I look at the "mega" ships, and think...what the hell would happen if that humongous thing were to tip over? And yes...it can.

 

I wouldn't want to be on it, when that happens.

Edited January 27, 2017 by cb at sea

[Tapi]

I sailed for the first time on the 16,000 ton Cunard Princess. A few years later, I was baffled when I sailed aboard the 32,000 ton Tropicale. I was baffled once again when I sailed on the 73,000 ton Monarch of the Seas. Then again on the 100,000 ton Carnival Destiny. And again on the 130,000 ton Carnival Dream and finally when I sailed on the 225,000 ton Allure of the Seas.

 

I don't have an answer to your question, but all I know is that 35 years ago, I would've never even envisioned something like the Allure, so I won't be surprised if 35 years ago I'm baffled by a ship concept that nobody has even thought about today.

 

 

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[mamasylvia]

I'm still trying to figure out why they don't tip over. I look at those enormous sections above the waterline and mentally position the center of gravity way up in the air. (I know they don't, but have NO idea why!)

[TheOldBear]

I'm still trying to figure out why they don't tip over. I look at those enormous sections above the waterline and mentally position the center of gravity way up in the air. (I know they don't, but have NO idea why!)

 

The actual center of gravity is much lower - open space does not weigh much compared to engines and other heavy bits. Ships are designed so that rolling motion produces a counteracting 'righting moment' that tends to force the ship back upright.

 

Wikipedia has an entry covering the basics of ship stability https://en.wikipedia.org/wiki/Metacentric_height

[BoiiMcFly]

I look at the "mega" ships, and think...what the hell would happen if that humongous thing were to tip over? And yes...it can.

 

I wouldn't want to be on it, when that happens.

 

Wouldn't that apply to any ship though? Does it being larger make it less safe? And if they were tipping over left and right, people wouldn't be cruising. With any form of transportation there is always a small risk involved.

Edited January 27, 2017 by BoiiMcFly

[chengkp75]

The actual center of gravity is much lower - open space does not weigh much compared to engines and other heavy bits. Ships are designed so that rolling motion produces a counteracting 'righting moment' that tends to force the ship back upright.

 

Wikipedia has an entry covering the basics of ship stability https://en.wikipedia.org/wiki/Metacentric_height

 

Yes, the engines, boilers, propulsion equipment, and all the stuff that provides the cruise the ability to do what it does, is heavy and down below the waterline. Also, things like fuel, potable water, and ballast water account for tens of thousands of tons of weight, and this is kept in the very bottom of the ship. Also, the superstructure of the ship (all decks above the promenade deck), add almost nothing to ship strength, so it is built with lighter materials, and thinner metals than the hull, further moving the center of gravity down.

 

One way to look at it, the passenger spaces (the vast majority of the volume of the ship) is filled with air and passengers, while the engineering spaces are filled with heavy machinery. Think of the "punch-em" clown blow up toys, where it is nearly 5 feet high, but a small weight in the bottom keeps it coming back upright no matter how hard you hit it.

[Wellard]

A really great thread and an interesting to read. I've learnt a lot. Thanks all.

 

 

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