Factors Determining the Size of Post World War II Warships?

[Delta Force]

Before World War II, the size of a warship had a direct relationship with combat performance, with larger ships typically having heavier armor and armament. Larger ships are also more seaworthy and have higher endurance. After World War II, ships started using guided missiles and only minimal splinter armor (if any) was used. Smaller ships also became more seaworthy and longer endurance. Nuclear power also offered ships virtually unlimited endurance at speed.

Given these changes, what kinds of factors influence the size of post-World War II warships? Why have smaller ships such as corvettes, frigates, and destroyers increased significantly in size over the decades, while aircraft carriers in many navies (obviously not USN supercarriers) haven't changed size much relative to the light carriers and fleet carriers of World War II, and cruisers (except for the Kirov class) are smaller than World War II cruisers?

 

[Delta Force]

Apart from ship construction limitations and port limitations (navigating channels, etc.), is there any reason not to make a ship physically larger, since it improves many characteristics and is not as expensive as the systems that go into the ships themselves? Why not make 5,000 ton corvettes and frigates for defending convoys and cruisers the size of World War II heavy cruisers for more intense surface warfare operations?

 

[Petros >Peter Fergus<]

Coming up to the present day, ship size is limited by the power of ship-borne missiles, and the vulnerability of modern weapons, detection and communication systems, which must necessarily be exposed on the deck of the ship. One missile hit might not be able to sink a cruiser, but it can mission kill it by making it dumb and blind, and by detonating the missiles in the tubes. If their point defenses are disabled by the attack, it's ability to resist further attack is reduced, so further hits could actually sink it. If the battle is lost, it can steam back to port and be refitted, but only if losing the battle didn't lose the war.

If you distribute the same number of tubes and missiles among ten times as many ships, you might lose some in the battle, but you'll have more mission capability for longer in the battle itself.

Then we have aircraft carriers (longer runway is safer, larger ship is more stable), and submarines (not certain about the advantages of being larger or smaller here).

 

[Morningfog]

Given these changes, what kinds of factors influence the size of post-World War II warships? Why have smaller ships such as corvettes, frigates, and destroyers increased significantly in size over the decades, while aircraft carriers in many navies (obviously not USN supercarriers) haven't changed size much relative to the light carriers and fleet carriers of World War II, and cruisers (except for the Kirov class) are smaller than World War II destroyers?


Corvettes, frigates and destroyers have increased in size because of machinery and equipment requirements. Their roles have also somewhat changed. Destroyers are now the main surface ship for most navies around the world. Thus, they also require some form of survivability (endurance) which size can also permit.
Carriers haven't changed in size because they need a runway and carrier planes haven't been altered to the point that a much longer/wider runway/deck is required. Thus, carrier size is proportional to plane capacity and also the ability to build and maintain them (hence why the US has so many).
Cruisers are being phased out by most navies and destroyers are more or less taking up their role.

 

[CarribeanViking]

One very important argument is that steel is cheaper than silicon. Most of the cost of a ship is in its' electronics, the sensor and weapon fit; the hull is a relatively small fraction of the total. A larger hull offers advantages in damage tolerance, layout- larger ships have more room for redundancy, avoiding system interference, making command and control easier.

The streetfighter concept, multiple small craft, you have to either accept that the ships are nearly blind and running on command downlinks, or duplicate the sensor suites across multiple platforms so they can function independently. Massive cost spike.

That and fast attack craft have a rotten combat record. They hardly ever win, because they're too cramped, can't afford to lay their systems out efficiently, don't have room to think, there's hardly anywhere you can hit them without hitting something important, and they tend to be relatively highly stressed and malfunction prone.

Another surprisingly important driver is living conditions. You can't fit electronics technicians in hammocks on the gun deck anymore; highly skilled personnel require a bit more generous providing for. Even at that most navies have personnel retention problems these days.

 

[Mr.brightside]

Interesting. Are current large destroyers or cruisers compromised by size? What kind of advantages would a heavy cruiser sized ship have? And I feel like we have to discuss the Kirov in this thread. What advantages did it have over smaller soviet ships?

 

[Riain]

Just like in ww2 ship size is determined by the capabilities required, whether that be to give and receive 8" gunfire or to operate two large ASW helicopters in rough weather. Indeed the requirements of operating helicopters has been a major driver of ship size since the 60s.

 

[Dunning Kruger]

I am guessing cost vs. survivability in a nuclear environment played a big role. Increasing the size of a carrier probably doesnt do enough to improve its lifespan but it would increase the cost of the ship. As to the destroyers and frigates, does size help them in an ASW role - speed, electronics, helopad, etc?

 

[Johnestauffer]

The space required for the electronics systems and associated electrical power supplies has increased (and continues to increase). Also the space allocated for command and control (CIC) space has grown.

Missiles require substantial "below decks" space, so a ship needs to allocate more space for the larger munitions and associated control systems.

Command ships (such as Guided Missile Cruisers) have additional berthing space for the staff personnel and expanded CIC's to allow more staffing.

As an aside, the improved berthing requirements for some USN ships have resulted in more space for the crew than would be needed in a WW-2 or 1950's era ship.

 

[jsb]

while aircraft carriers in many navies (obviously not USN supercarriers) haven't changed size much relative to the light carriers and fleet carriers of World War II,

IMO CVs have needed to get much bigger (due to faster heavier aircraft) this has been disguised by nobody but the USN building proper CVs (everybody else is just building CVL or CVE types and pretending they are CVs)

Given these changes, what kinds of factors influence the size of post-World War II warships? Why have smaller ships such as corvettes, frigates, .....and destroyers increased significantly in size over the decades, and cruisers (except for the Kirov class) are smaller than World War II destroyers?

You now have 3 types of warship, (but they have all got bigger due to lots of reasons not least that size isn't limited and isn't that expensive)

Subs
Virginia 7,800t v Gato 2,400t

Carriers
Nimitz 100,000t v Essex 36,000t

Surface ships (corvettes, frigates, destroyers and cruisers)

This is hard as they are all related and just a spectrum of how much you can pay and what systems you want of helicopters, SAMs, Radars, Sonar, Range etc (with the bigger ship having more and better)

 

[Trevayne]

snip

and cruisers (except for the Kirov class) are smaller than World War II destroyers?

This last statement is an error. WW2 destroyers were in the 1,500 - 2,500 ton range. Modern cruisers are in the 8-10,000 ton range.

If the OP meant modern cruisers are smaller than WW2 cruisers, not really. A Ticonderoga is about 9,600 tons, so in the middle of the treaty cruiser range and smaller than most of the post treaty ships like the Baltimores.

As for why modern ships aren't bigger, yes, steel is cheap. However, the fuel to drive a ship at 25-30 knots isn't. You could build an Aegis cruiser on a 20,000 ton hull. It would have more magazine space, and resistance to battle damage, but it would also cost more both to procure and operate.

 

[hx87]

Cruisers are smaller than WWII destroyers? I must have forgotten about all those 9200 tonne DDs from that war...

IMO the most important factors are electronic warfare, strategic endurance, and combat endurance. When you need radars with ranges of 500 km or more to defend against aircraft and missiles, you need massive antennas for those radars (no matter how efficient and miniaturized the electronics are)and a powerplant large enough to supply them. Below 5000 tonnes or so the antennas you can fit become too small for the purpose, and reciprocating diesel engines (and thus CODAG) become impractical so you have to rely on thirsty gas turbines for all your power. Which leads to the next issue...strategic endurance.

Fuel capacity scales with the mass of the ship whereas fuel consumption scales closer to the cross sectional area. Therefore all other things considered larger ships have greater range and deployment endurance. If your ships are for coastal defense is not an issue, but for blue water navies this is absolutely vital. You do not want your fleet to constantly need supplies from unarmed merchant ships more than is necessary.

So let's assume you're a green water navy and rely on land based radar to save on costs. Therefore you adopt a neo-Jeune Ecole doctrine and acquire a fleet of missile boats with two P-500 Moskits each. Ready to kill some carriers and battleships right? Well what do your missile boats do once they've fired off their two missiles? What if the carrier and its escorts shot down those missiles? What if the battleship got lucky with one of its 16" shells and shook off the other missing? Having a big missile carrier like the Kirov means you have other options once the first launch fails, whereas missile boats are easy pickings for surviving aircraft and destroyers.

 

[Delta Force]

Fixed the typo about cruisers being smaller than destroyers. I meant smaller than World War II light and heavy cruisers.

 

[Gunnarnz]

As to the destroyers and frigates, does size help them in an ASW role - speed, electronics, helopad, etc?

Yes. Larger ships offer more stable platforms for flight operations, to say nothing of the extra space they make available. For landing pads, hangar and maintenance space, room for electronics (and the associated power and cooling systems), crew quarters, and so on.
I'm less sure about speed but I have a vague idea that speed scales favourably as the length of the hull increases, so ton for ton a large ship will be faster ( as long as it doesn't have some weird hull form).

 

[Athelstane]

One ship type that has clearly gotten larger

is the submarine - and not just the ballistic missile submarines, which can be as large as a WWI battleship.

But that in itself may be telling. Guided missiles make ships much more vulnerable than they ever were to gunfire, torpedoes, or aircraft delivered aerial torpedoes and (dumb) bombs. There are ship defenses, but it' s a constant battle to keep up with anti-ship missile technology. A larger ship makes for a larger target, and not necessarily a more survivable one. The submarine has the advantage of being able to hide to some degree.

Fleet carriers are extraordinarily expensive to build and operate, and only the greatest powers even try. For most naval powers, one or two STOVL or helicopter carriers are adequate. You'd see more if there was a genuine naval arms race, but we have not had one of those in a while.

 

[GarethC]

How much does the size limitation of the Panama Canal affect US naval architecture?

 

[sparky42]

How much does the size limitation of the Panama Canal affect US naval architecture?

Since the Nimitz class they've just accepted sailing them round South America instead, so not a huge amount I'd say.