Is there an ultimate size in ocean going warships?

[mikewint]

From a purely physics standpoint, there really is no theoretical limit to the size of anything we can build. It would merely have to be strong enough in all the right places to withstand the stresses placed upon it, which at some point would come to be dominated by the structure's own gravity.
So as I posted earlier what do you want the ship to do?
Structures, whether terrestrial or seafaring, have to support their own weight at least. To be useful, they must also support the weight of anything they're intended to contain, and must further be able to withstand the stresses of any external forces they may be subjected to.
For a seafaring vessel, those forces can be massive; a rogue wave can tear a ship in half simply by lifting half of it clear of the water and letting it collapse under its own weight; the ship isn't designed to support that kind of "shear load" of its own hull. Making the ship stronger by making its hull and keel thicker necessarily increases the ship's mass, and therefore requires either a lower cargo mass limit, or a larger volume of displacement, which requires an increase in size, which increases the action of the forces inherent in the ship's size, which requires the structure to be stronger, increasing mass...
At some point, a ship would simply be too big to survive the pounding of even a relatively calm day at sea, to say nothing of an emergency situation like a hurricane/typhoon.
Shell Oil has just completed the PRELUDE a 488m FLNG weighing in at 600,000 metric tons which will be moored to the ocean floor off the coast of western Australia for the next 25 years.

 

[Night Fighter Nut]

I just see a bigger bomb magnet.

 

[GrauGeist]

Kind of an interesting page of facts and videos of the Seawise Giant that puts it's size into perspective (like the graphic showing that it was longer than the Empire State building is tall)
Biggest Ship in the World, Seawise Giant - Largest Ships

As far as bomb magnet, I don't know - something this massive would most certainly have some brutal defensive (and offensive) capabilities.

 

[syscom3]

I was thinking something like a Ford class carrier thats 50% bigger.
Or a radical amphib design that is a catamaran type with a wet well between the hulls and a huge flight deck to accomodate lots of helo's. Sort of like two Wasp class carriers side by side.

Could it be done from an engineering perspective using todays technologies.

Like I said, cost is irrelevent for the sake of discussion.

 

[mikewint]

Syscom, Ford class? 50% bigger? than what? The USS Enterprise CVN-65 was 1122 ft. long and 94,780 tons. The Ford class will be 1,106 ft. but will weigh 110,000 tons or 15,220 tons more though 16 ft shorter.

 

[syscom3]

Rounding it off, a super duper carrier thats 1500 feet long, with of course increased beam and displacement. But that might be at or beyond the extreme limits, from what some of you are saying.

 

[GrauGeist]

Sometng to keep in mind, is that with bulk, comes a compromise in performance.

Of course, the surface area of the Seawise was staggering, and if it were a carrier, it's air compliment would be double that of a current super carrier. Also as a combination carrier and battle platform, it's offensive abilities would be impressive.

However, the Seawise could only make 16 knots at best speed and it took her over five miles to stop. Steering was a nightmare and she had trouble navigating areas like the English Channel and a number of oil terminals, so there would be severe limitations on operational areas with a military application.

It seems that there is a certain point where too big is too much.

 

[syscom3]

Sometng to keep in mind, is that with bulk, comes a compromise in performance.

Of course, the surface area of the Seawise was staggering, and if it were a carrier, it's air compliment would be double that of a current super carrier. Also as a combination carrier and battle platform, it's offensive abilities would be impressive.

However, the Seawise could only make 16 knots at best speed and it took her over five miles to stop. Steering was a nightmare and she had trouble navigating areas like the English Channel and a number of oil terminals, so there would be severe limitations on operational areas with a military application.

It seems that there is a certain point where too big is too much.

Since price is not a concern for this thread, the super duper warship will have enough power to maintain 35 knots. Nor would it displace 400K tons so the performance in turning would be better. But then at 1500 feet, the hull would flex and twist a bit.

 

[pbehn]

Sometng to keep in mind, is that with bulk, comes a compromise in performance.

Of course, the surface area of the Seawise was staggering, and if it were a carrier, it's air compliment would be double that of a current super carrier. Also as a combination carrier and battle platform, it's offensive abilities would be impressive.

However, the Seawise could only make 16 knots at best speed and it took her over five miles to stop. Steering was a nightmare and she had trouble navigating areas like the English Channel and a number of oil terminals, so there would be severe limitations on operational areas with a military application.

It seems that there is a certain point where too big is too much.

I worked on a jetty at Yanbu Saudi Arabia it was to take very large ! million barrel tankers, these were just that, tanks that floated, it was a strategic move in the case of air attacks on tank farms.

 

[mikewint]

It seems to me that many of the posts here are not germane to the original post which simply asks if there is a theoretical size limit for a ship. Is there a floating mass big enough so that it collapses under its own weight, i.e. A boat is structurally very similar to a bridge (or an airplane wing). At its worst case (e.g. in very heavy seas) it will be supported by the ends, or entirely in the center with one/both ends cantilevered. For a given length, mass, etc, a certain amount of strength is required to meet the structural needs of a boat hull. So what are the physical structural limits of steel?
All materials have some limit in strength that creates an upwards boundary for the maximum size structure practical with that material. Let's shift to wood which is probably easier to imagine. Take a board 1000ft (300m) long, lift it by one end, it breaks under its own weight. Making the board thicker does not help as that simply increases weight without altering the internal strength of the wood. Thus wood's limit For boats is a few hundred feet. A single tree might reach 80 m so a ship bigger than that require seams. Wood is flexible so in heavy seas the flexing and sagging opens those seams.
That's why I initially asked/answered: It depends on what you expect the ship to do:
Just float - Japan, back in the '90 built a floating airport in Tokyo Bay, the Megafloat. The initial test structure was 1,000 m long and engineers felt that 4,000 m structures were certainly possible. Now these JUST float. they are anchored in place and are protected by breakwaters.
Float and move: The Seawise Giant/Knock Nevis/Jhare Viking is a baby compared to the proposed FREEDOM a city-ship 4320ft (1317m) long, 225m (738ft) wide ship, 25 stories high grossing 2.7 million tons. It would house 50,000 people and circle the globe every two years. I hasten to add that this is a PROJECT at present. Started in 1999 at a projected cost of 6 billion USD it has jumped to 11 billion in 2013. It is also not a single ship but 520 airtight "barges" all linked together. 70% of its time will be spent docked outside major cities and will move only under the most favorable weather.
For the practical-minded the BARZAN container ship is the largest active in-service ship at 400m and 195,636 tons and the PIONEERING SPIRIT (crane ship) the widest ship (twin hulls) at 124m wide and 382m long. The four TI-class super tankers are the largest by tonnage at 234,006 tons though only 380m long.
So the ultimate answer here depends on someone who knows A LOT more about the properties of structural steel than I.

 

[GrauGeist]

That's why I initially asked/answered: It depends on what you expect the ship to do

Sys was asking how big of a warship was possible...

And while the TI class are large, the Seawise still exceeded the TI class in DWT (Seawise - 564,763 | TI class - 441,585)

So as an active warship on the high seas, I just don't see anything bigger than Seawise (or the TI class) as being practical. As it stands (as I've mentioned earlier), these monsters are extremely limited on where they go and if you're in the business of force projection, destination limitations is a serious liability.

With a top speed of 16 knots (both Seawise and the TI class held this as max speed), you are putting your battle group at risk. It takes a tremendous amount of power just to get these beast up to 16 knots, over 5 miles to come to a stop and over 3 miles to turn. Trying to apply more torque and horsepower to increase speed will mean additional distance to full stop, a wider turning radius and the risk of snapping driveshafts if a full reverse is performed (for emergency stop). The prop alone, on the Seawise, weighs 50 tons...add to that the strain of the forward inertia by the mass of the ship and even a moderate braking with current powerplants is still a massive strain on the drivelines.

Also, current carriers and even battleships have a good deal of maneuverability (of course, nothing like a DD or Frigate), which is essential to evade attacks...you are simply not going to have this luxury with a sea-going colossus...so you had most certainly better have defenses of the highest order on hand.

So I firmly believe that the Seawise is about as large as you can get for a warship and still be within the limits of practical function...

 

[Lucky13]

How about these engine pods that's so popular now then, how big can you make those, before they're too big?

 

[mikewint]

Dave, IMHO you have missed the point of the question which asked THEORETICAL limit and that has nothing to do with practicality or any other consideration except size/mass.
Seawise is a dead pony in any case having been broken up for scrap in 2009 which kind of answers practically questions
Now despite her great length, Seawise Giant was not the largest ship by gross tonnage, ranking fifth at 260,941 GT, behind the four 274,838 to 275,276 GT Batillus-class supertankers. She was the longest and largest by deadweight: 564,763 metric tons. Batillus-class ships and Seawise Giant were the largest self-propelled objects ever constructed. But still does not answer the theoretical limit question.
Back to Seawise which was originally designed as a smaller ship. During the construction process it was jumboized, i.e. a new middle section was added between the bow and stern

 

[GrauGeist]

But Mike, that is my point.

Seawise served as a functional ship until sunk during the Iran-Iraq war, after which, it was salvaged but ended up as a floating storage/transfer unit, much like a couple of the TI class super tankers do today.

So I am using Seawise as an example of the maximum limit in practical size for a warship...anything beyond that is useless. So I imagine that yes, even with today's technology, there *could* be a seagoing vessel much larger, but as I pointed out already, it would not provide any benefits for the expense, time materials to construct.

There reaches a point where absolute size works against nature instead of with nature. The An-225 is about as large of an aircraft (civil, military or otherwise) that you can get, with today's technology, and still be useful. The same can be said for armored fighting vehicles, where, during WWII, they kept getting larger and larger (with even larger on the drawing board) and they simply reached a point where their size was a liability rather than an asset.

So that's my input in answer to Syscom's question: "is there an ultimate size in ocean going warships"

 

[mikewint]

Dave, mayhap my reading of the question is skewed. While I totally agree with your assessment, though I would hold that the Seawise was impractical from the start, more of a company whizzing contest else the ship would still be in use today and not scrapped.
IMHO to correctly answer the posted question the word practical cannot be used in any context. Using unlimited funds, unlimited material, and all existing technology:
WHAT IS THE LARGEST SHIP THAT CAN BE BUILT
I found this graphic and thought it pretty cool. To scale: the Pentagon, Queen Mary, USS Enterprise, Hindenburg, Yamamoto, Empire State Building, and the goode olde Seawise Giant.

 

[pbehn]

The seawise giant is a completely different type of ship, just imagine the waterlines. When new the oil that costs $2 per barrel to produce is worth more than the tanker carrying it.

Does anyone know what the latest US carriers with full compliment of F35s will cost?

With no budget limit there is no reason why a monster couldnt be made, the troll A platform weighs 683,000 tons, about the same as the seawise giant when loaded.

 

[mikewint]

The Ford-class program has cost $30.30 billion and the ship itself CVN-78, $10.44 billion USD as of 2015FY. The USS Gerald Ford will replace the USS Enterprise which has served for 51 years. Next up will be the USS John Kennedy CVN-79 to replace the USS Nimitz of Final Countdown fame. CVN-80 will be the USS Enterprise 9th ship to carry that name.
So using present day tech a 5,280ft long 4 million ton "ship"? Much as Buckminster Fuller proposed in the 1950s. What are the ultimate limits?

 

[Lucky13]

Isn't the new carriers supposed to go back to the old way of naming them, with the first one being named USS Enterprise?
Saw it somewhere, it's also been on the picturebox.....
#$£%¥€§€§%*£$ if I can find it now!

 

[Lucky13]

Isn't the new carriers supposed to go back to the old way of naming them, with the first one being named USS Enterprise?
Saw it somewhere, it's also been on the picturebox.....
#$£%¥€§€§%*£$ if I can find it now!

 

[GrauGeist]

Isn't the new carriers supposed to go back to the old way of naming them, with the first one being named USS Enterprise?
Saw it somewhere, it's also been on the picturebox.....
#$£%¥€§€§%*£$ if I can find it now!

The very first U.S. carrier was the Langley (CV-1)

Next was the Lexington, Saratoga, Ranger and then Yorktown.

The Enterprise was sixth one built.

The names of these carriers have been used on newer carriers over the years.

Langley: CV-1, CVL-27
Lexington: CV-2, CV-16
Sararoga: CV-3, CV-16
Ranger: CV-4, CV-61
Yorktown: CV-5, CV-10
Enterprise: CV-6, CV-65