Is there an ultimate size in ocean going warships?

[syscom3]

I was looking at the specs for the new Ford class carriers and wondered this;

The length was increased to 1500 feet to allow longer catapults for heavier aircraft to be launched.
The beam widened to accomodate faster ops on the deck and more hanger space. Maybe even torpedo blisters for more protection.

I understand that increasing size means more displacement, thus power requirements. But I also got to wondering if there are structural bending moments that make massive sized ships problematic for radical maneuvering at full speeds.

Your thoughts?

 

[Glider]

The limitation is in the ability of the ports to supply/service/handle them

 

[fubar57]

I think one of the factors for U.S. warships was/is fitting through the Panama Canal.




Geo

 

[syscom3]

If the USN decides not to dimension a warship to pass through the canal.

 

[syscom3]

The limitation is in the ability of the ports to supply/service/handle them

The USN decides to dredge the ports these vessels will dock at.

 

[at6]

Any well designed ship can be built to any size, but where can it be docked? Building a port capable of berthing it would be cost prohibitive at some point.

 

[syscom3]

Any well designed ship can be built to any size, but where can it be docked? Building a port capable of berthing it would be cost prohibitive at some point.

If a navy wants a mega sized ship, it will accept tje costs that come with it.

I am wondering if there is a limit for the size of it due to structural limitations.

 

[pbehn]

If a navy wants a mega sized ship, it will accept tje costs that come with it.

I am wondering if there is a limit for the size of it due to structural limitations.

I dont know about the physical limits but I suppose there will be a size where cost and utility of one huge carrier is overtaken by two smaller ones, its a big basket to put all your eggs in.

 

[Glider]

The USN decides to dredge the ports these vessels will dock at.

If the assumption is that the US will dredge whatever is needed then in theory there is no limit. Remember that the ships will only be able to operate in the ports that have been dredged and as they will only be able to operate from those ports, the concept of a world wide navy is history. Any significant damage will be irreparable until they get home.

 

[syscom3]

Adding 200 to 300 feet in length and 50 feet in beam wouldnt be that big of a deal.

But is there some physical limit in size they can get before structural issues become a factor, like flexing and twisting in heavy seas.

 

[GrauGeist]

There are some supertankers and cargo carriers that are staggering in physical size and displacement, if they can produce ships of this size and capacity, then they can certainly apply the same engineering to a warship.

For instance, the TI class super tankers (currently the absolute largest ships on earth) have a length of 1,246 feet (380m), beam of 223 feet (68m) and a draught of 80 feet (24.5m) with a fully loaded displacement of 509,484 tons. The Seawise Giant is the absolute largest ship ever built, with a length of 1,504 feet (458m) a beam of 225 feet (68.8m) a draught of 80 feet (24.6m) and a fully loaded displacement of 646,642 tons. (Seawise was sunk during the Iran-Iraq war)

The EEE cargo ships are the longest at 1,312 feet (400m), they are second in absolute capacity (that title goes to the container ship MSC Oscar).

 

[pbehn]

Wiki entry on the seawise giant says it couldnt pass up the English channel.

 

[bobbysocks]

where are they going to dry dock it? sooner of later it will need to go in for repair and maintenance...

 

[mikewint]

If we ignore the above posts about harbors/docks/Panama Canal size limitations then buoyancy is your only limitation in a calm sea. Now as wind and waves increase we have more problems to solve so, I guess the question to ask here is: Under what conditions? Consider waves: A ship has to "span" (like a beam) between the crests of waves while subject to torsional (twisting) and shearing forces. There are tremendous dynamic loads from the sea and wind. The unsupported center could easily break/buckle. The Edmond Fitzgerald may have sunk in such a manner. The bigger the ship the stronger it has to be. I can easily see how you could reach a point where the ship needs so much structure that it's all beams and trusses.
Now consider Rogue Waves: On the open sea, waves can commonly reach seven meters in height; or even up to fifteen in extreme weather. In contrast, some reported rogue waves have exceeded thirty meters in height. Most modern vessels are designed to withstand about fifteen tons of pressure per square meter, but these unusual waves exert a pressure of about one hundred tons per square meter.
Sailors have reported these Rogues for hundreds of years but were never taken seriously. In 1933 in the North Pacific, the US Navy transport USS Ramapo triangulated a rogue wave at thirty-four meters in height. In 1942, the RMS Queen Mary was transporting 15,000 US troops to Europe when it was hit by a twenty-three meter wave and nearly capsized. The giant vessel listed by about 52 degrees due to the impact, after which it slowly righted itself.
In 1978, the 37,000-ton MS Munchen radioed a garbled distress call from the mid-Atlantic. When rescuers arrived, they found only "a few bits of wreckage," including an unlaunched lifeboat with one of its attachment pins "twisted as though hit by an extreme force." It is now believed that a rogue wave hit the ship, causing it to capsize and sink. No survivors were ever found.
In 1996, the Queen Elizabeth 2 encountered a rogue wave of twenty-nine meters, which the Captain said "came out of the darkness" and "looked like the White Cliffs of Dover." London newspapers said that the captain situated the vessel to "surf" the wave to avoid being sunk.
Project MaxWave was created by 11 organizations from six EU countries to investigate rogue waves. Using two European Space Agency satellites, the project used radar to map the surface of the oceans over a three-week period. During this period, 10 massive waves were identified, all over 25m feet in height. Several were nearly 30m in height, from crest to trough.
The Knock Nevis/Jahre Viking is/was the largest ship at 458m in length. The Queen Mary comes in at 345m and the USS Enterprise is 342m. The new Ford class will be 338m
http://video.dailymail.co.uk/video/1418450360/2014/11/1418450360_3894706572001_ship.mp4

 

[GrauGeist]

Wiki entry on the seawise giant says it couldnt pass up the English channel.

Yep..there's a certain point where size actually puts limits on any benefits

where are they going to dry dock it? sooner of later it will need to go in for repair and maintenance...

Many places to go for refitting or maintenance.

Seawise was built in Japan, they have deepwater facilities, same with Hyundai's facilities. China has several, in the U.S., there's deepwater ports in San Francisco, Los Angeles and in Washington plus several on the Atlantic seaboard. I believe Sydney has deepwater facilities as does Melbourne (I think, not 100% sure)?

 

[parsifal]

The limit is not really related to engineering limitations. existing warship designs work well within the limits of engineering possibility.

The main constraint is operational. Effectively having a carrier twice the size, with presumably twice the complement and twice the air capacity will inevitably mean you have half the number of hulls. and the number of hulls at the moment is barely enough to meet USN world commitments as it stands. reduce the numbers further and you end with period of time where there is no carrier to cover ops in a certain part of the world. No prizes when an enemy will choose to strike in that scenario,,,,just when a given carrier normally assigned to cover a certain part of the world is in drydock for refit and repair.

Virtually the entire post war US strategy of sea control is predicated on having at least one carriers to cover that operational area at any given time. reduce the numbers of carriers below the minimum requirements and the strategy comes under threat.

Carrier size is linked to numbers, and numbers is what governs the effectiveness of US naval strategy since the end of WWII. the US needs more hulls, not less, even if that means smaller, less capable ships, with smaller less effective air groups

 

[pbehn]

If we ignore the above posts about harbors/docks/Panama Canal size limitations then buoyancy is your only limitation in a calm sea. Now as wind and waves increase we have more problems to solve so, I guess the question to ask here is: Under what conditions? Consider waves: A ship has to "span" (like a beam) between the crests of waves while subject to torsional (twisting) and shearing forces. There are tremendous dynamic loads from the sea and wind. The unsupported center could easily break/buckle. The Edmond Fitzgerald may have sunk in such a manner. The bigger the ship the stronger it has to be. I can easily see how you could reach a point where the ship needs so much structure that it's all beams and trusses.

There were a few large tankers lost in the early days but not in especially violent storms. They suspected it was resonance but they went down with no mayday message. One shipyard in N/E England was closed when a tanker was lost and it got no further orders, I cant remember the ship or the shipyard, maybe Stona remembers.

To stop a long ship flexing it must become wider and deeper eventually so wide and deep it will take an age to deploy a few hundred miles from where its needed.

30ft waves are routine in a North Sea winter but rigs are designed for 90ft rogues.

 

[syscom3]

My question is in regards to structural limitations. Not the pro's and con's, nor expenses of such a warship.

 

[Capt. Vick]

Budget

 

[GrauGeist]

My question is in regards to structural limitations. Not the pro's and con's, nor expenses of such a warship.

I think we'd have to look at how they solved the problems with the supertankers and giant cargo ships.

The Seawise had several issues that took a number of years of refitting to correct, but worked fine afterward.

I would say that the Seawise is about as big as you're going to get with today's materials and technology.