Wiki Discussion: Ship Mission Codes (Naval History Terminology)

[whulorigan]

From the Ship Mission Code Thread:

I suppose we use navy terms for ship mission codes because we want to make sense at some level.

Not being a navy person, my exposure to these terms is mostly via classic Traveller, so my view is skewed.

This thread is an addendum to the Ship Mission Code Thread. I put it here so as not to clutter up the thread, as this is a somewhat long (and tangential) post. This thread is for a discussion of the history of naval (or other) ship classification terminology.

 

[whulorigan]

Some Terminology background:

Part 1 of 5: Age of Sail

During the Age of Sail, warships were Rated (1st thru 6th rate) based on the number of guns they carried. All such ships required a “Post-Captain’” as a commanding officer (i.e. someone with a proper naval rank of Captain, as opposed to simply the courtesy title).

• A Ship-of-the-Line-of-Battle (i.e. “Battleship”) had enough guns to require multiple gun decks and generally comprised Rates 1 (largest/best) thru 4 (smallest). Such ships were only brought out for fleet action in time of war.
• A Frigate comprised Rates 5 thru 6 and had their guns on a single deck. They supported the line of battle in fleet actions, but were also the independent long-range multi-mission cruising ships employed by the navy for other operations (war or peacetime).
• A “Post-Ship” (later a Corvette or Sloop-of-War) comprised the smallest ships of Rate 6, though some of the class were small enough to be “Unrated” (and would presumably only require a Master and Commander of the rank of Lieutenant in command). Corvettes primarily acted as patrol and anti-piracy vessels and small combatants not usually associated with main-battle operations.
• Gunboats as a class were Unrated and smaller than Corvettes or Sloops-of-War, and were generally coastal or riverine vessels.

​

Note: A vessel was also classified as to the number and type of masts. The "mainmast" was always the largest (and centermost) mast - all other masts were gauged relative to it. A "Ship" (proper) had 3 or more masts (foremast, mainmast, and mizzenmast (aft)). Some of the smallest vessels in the Corvette/Sloop-of-War range only had two, making them properly "Brigs", NOT "Ships", with either a fore- and mainmast, or a main- and mizzenmast. Later "sloops" (civilian) during the Late 18th-19th Century were very different from Sloops-of-War and should not be confused with them, having only a single mast and a long bowsprit, with the sails rigged fore-and-aft between the bowsprit, mast, and stern (for a large sail-area compared to the hull displacement), as opposed to the two and three masted Sloops-of-War, which were all rigged square on all masts.​

 

[whulorigan]

Part 2 of 5: Early 20th Century

During the late 19th – early 20th Century the most formidable steam-powered warships of the “Battleship” (BB) class came to be known unofficially as “Dreadnoughts” [sic] (after the British Battleship HMS Dreadnaught at the turn of the 20th Century). Steam-driven Cruisers replaced the earlier termed (sailing) Frigate for the fleet workhorse vessels, and the new class of “Torpedo-Boat Destroyer" (later just Destroyer - DD) emerged to defend slow lumbering Capital ships from small, fast steam-powered gunboats armed with the new “torpedo” weapon that they were otherwise almost defenseless against. As torpedo boats were replaced by Submarines (and later other air and seaborn offensive threats) the armament and tactics of the Destroyer (DD) shifted to meet those new threats while retaining their primarily defensive mission as a fleet escort. The smallest patrol assets were Gunboats (PG).

Note: As the Cruiser class evolved they eventually were reclassified as: Armored Cruiser (later Heavy Cruiser - (CA)), Light Cruiser (CL) and later also the Carrier (CV - as the first Airplane Carriers were modified Cruisers with a flat-top).

 

[whulorigan]

Part 3 of 5: Second World War

During the Second World War, much mercantile shipping was threatened by submarine warfare, and merchant ships and convoys were vulnerable. In the USN a new class of vessel (the “Destroyer Escort” (DE)) was conceived to fulfill the same role for merchant convoys as the Fleet Destroyer did for battle fleets. Because merchant convoys are generally much slower than naval vessels, Destroyer Escorts (DE) did not need to meet the much higher Fleet mobility standards of Fleet Destroyers (DD), and thus could have smaller engines and armor (and were smaller, cheaper and faster to build). The British resurrected the term “Sloop-of-War” for vessels of this type in the Royal Navy (RN).

 

[whulorigan]

Part 4 of 5: Cold-War

During the Cold War, many of the USN WWII vessel classes were decommissioned, the remainder being reclassified. The few remaining Heavy Cruisers (CA) were simply known as “Gun Cruisers” (as they did not mount the more sophisticated guided missile systems that were emerging). Destroyers (DD) and “Destroyer Leaders” (DL) were reclassified in the USN as “Frigates” (retaining the DD/DDG and DL/DLG hull classes as Guided Missiles were added to their portfolio). The former Destroyer Escorts (DE) were re-designated as “Ocean Escorts” (still DE or DEG). The USN also added a class of “Patrol Frigate" (PF) to the mix that was smaller than an Ocean Escort in order to add confusion.

In other nations, Heavy Cruisers (of the type mentioned above) were largely being decommissioned, and other nations' cruisers generally fell into the size range of the USN “Destroyer Leaders” (DLG - re-designated USN “Frigates”). USN smaller Frigates (DD/DDG) were comparable to other nation’s Cold-War-era “Destroyers”. To add confusion, other nations began to typically call their equivalent of the USN Ocean Escort (DE/DEG) a “Frigate”.

The “Cruiser Gap” and “Reclassification”

This cold war reclassification eventually led to a perceptual problem with the USN as compared to other world navies known as the “Cruiser Gap”. It was perceived that the USN had far fewer cruisers than most other navies. This was not true of course – the problem arose from the differing terminologies of the USN as compared to the others. USN “Cruisers” were a small number of hold-overs of WWII Heavy Cruiser (CA) retrofits still in service, while other navies’ “Cruisers” were comparable to USN Frigates (DDG/DLG) of which there were a much larger number. Further the other navies using “Frigate” to refer to what the USN termed and Ocean Escort (while calling their “cruiser”-style vessels “Frigates” (DDG/DLG) led to major conceptual confusion.

USN (pre-mid-1970s)	Other navies
Cruiser (CA)	(n/a)
Frigate (DLG)	Cruiser
Frigate (DDG)	Destroyer
Ocean Escort (DEG)	Frigate
Patrol Frigate (PF)	Frigate

So in the mid-1970’s, the USN brought its classification system into line with the rest of the world – it decommissioned its remaining Gun Cruisers (CA), and split its Frigates into the larger ones (DLGs) renamed “Cruisers” (CG) and the smaller ones (DDGs) renamed “Destroyers” (DDG). The older Ocean Escorts (DEG) and Patrol Frigates (PF) now comprised the role of the new designation "Frigate" (FFG).

USN (post-1975):

• Cruiser (CG) - Main combatant / Mutli-mission
• Destroyer (DDG) - Fleet Escort / Mutli-mission
• Frigate (FFG) - Escort / Anti-piracy / Patrol

 

[whulorigan]

Part 5 of 5: Traveller

Traveller seems to divide its naval vessels into the following broad categories:

• ACS – Colonial/Provincial/Planetary Assets (small-ship universe)
• BCS – Capital/Imperial Assets (big-ship universe)

With Traveller’s divide into ACS and BCS ships, it seems that the ACS Naval Ships have traditionally drawn their terminology from a generalized version of the pre-1970’s USN Cold War usage, and the BCS ships use the post-1970’s Cold War terminology as their basis. And again (in its own unique Traveller way), the problem becomes the definition of the Cruiser.

ACS – Colonial/Provincial/Planetary Assets ("small-ship universe")

1. “Main/Large” = (Colonial) Cruiser (800-2000 ton)
2. “Major” = Frigate (600-1000 ton)
3. “Minor” = Corvette (Escort) / anti-piracy / local patrol and action (under 800 ton)

BCS – Capital/Imperial Assets ("big-ship universe")

1. “Main/Large” = Capital/Primary = Battleship (largest/best are Dreadnoughts) (100 kton +)
2. “Major” = Capital (“Imperial”) Cruiser (various classes) (20 – 100 kton)
3. “Minor” = Fleet Escorts (Destroyers and other Auxiliaries) (5-10 kton or less) – equivalent to ACS “Colonial Cruiser” size – minor combatant

Putting these together (in decreasing size):

1. BCS Capital/Primary “Battleship” ("Dreadnought" = Best-in-Class) ( - Offensive - )
2. BCS Capital Cruiser ( - Offensive - )
3. BCS Fleet Escort ("Escort Cruiser" / Fleet Destroyer) ( - Defensive - )
4. ACS "Colonial" Cruiser * ( - Offensive - ) / Monitor ( - Defensive - )
5. ACS Frigate ( - Offensive - ) / Defender (Destroyer Escort) ( - Defensive - )
6. ACS Corvette ( - Offensive - ) / Escort (Close/Gunned Escort) ( - Defensive - )
7. ACS Gunboat or Torpedo Boat ( - Offensive - ) / SDB ( - Defensive - )

* Note for ACS: CT, MT, and T5 have referred to naval small-ship universe cruisers explicitly in-print in 800, 1000, 1200, and 2000 ton sizes.​

 

[tjoneslo]

Early 20th Century

This entire period from about 1850 to the Washington Treaty in 1922 is one of constant change and reclassification in naval ship building. You have the shift from Sail to steam, the rise of the Ironclad, ever increasing size, power, and number of guns, and ever increasing engine power. The HMS Dreadnought was outclassed by ships built just 5 years later.

It may be useful as an example of how ship building between two (or more) pocket empires in a cold/warm war may later the definitions with each new ship produced. Say Milieu 0 with the Sylean Federation and Chanestin Empire and the few other empires around them.

 

[whulorigan]

Another observation is that historically, naval doctrine and tradition held to the notion that a naval vessel should be sufficiently armored to withstand a hit from one of its own guns. *

* (This in part is what led to the international naval arms race prior to WWI and its ongoing increase in size and armor of naval vessels as the British RN made it its policy to have a navy equal in size to the sizes of the next two largest world navies combined).​

The concept of the "Battlecruiser" arose during this period as a major departure from traditional naval doctrine, in which a large cruiser was armed with battleship-scale guns while retaining only cruiser-rated armor. The tactical concept was that the Battlecruiser could destroy anything within its own size class, while being able to outrun/outmaneuver anything that could seriously damage it. Unfortunately the Admiralty did not grasp the mission concept of the class and usually treated the Battlecruiser as simply a fast battleship with the result being that while they could damage other battleships, they themselves got slaughtered in the line of battle with their lighter armor.

 

[Spinward Flow]

The HMS Dreadnought was outclassed by ships built just 5 years later.

But those ships that appeared after took the form that they did BECAUSE of HMS Dreadnaught making every other ship afloat obsolete when HMS Dreadnaught launched.

 

[Condottiere]

1. The reason that warships started to be so carefully classified were due to the requirements to adhere to arms limitations treaties, specifically Washington and London.

2. You could find a couple of loop holes if you looked hard enough, if you didn't just plan on outright cheating.

3. Some of the definitions were gerrymandered to fit into existing interests.

4. Some of what follows are my definitions.

5. Dreadnought - fast battleship with ten twelve inchers; technological level twelve battle ship of the line with meson spinal mount.

6. Super dreadnought - fast battleship with ten thirteen and a half inchers; technological level thirteen battle ship of the line with meson spinal mount.

7. Fast dreadnought - very fast battleship with eight fifteen inchers; technological level fourteen battle ship of the line with meson spinal mount.

8. Intermediate fast battleship - very fast long range battleship with eight fifteen inchers; technological level fourteen battle ship of the line with meson spinal mount.

9. Fast battleship - very fast long range battleship with nine sixteen inchers; technological level fifteen battle ship of the line with meson spinal mount.

A. Dreadnought armoured cruiser.

B. Battle cruiser.

C. Grand cruiser.

D. Super cruiser.

E. Large cruiser.

F. Scout cruiser.

G. Scout aviation cruiser.

H. Protected cruiser.

I. Armoured cruiser.

J. Light cruiser.

K. Heavy cruiser.

M. Anti aircraft cruiser.

N. Semi armoured cruiser.

O. Unprotected cruiser.

P. Armed merchant cruiser.

 

[whartung]

Interesting stuff here all, thanks.

 

[Condottiere]

And apparently, there is a difference between battlecruiser, and battle cruiser.

 

[McPerth]

The concept of the "Battlecruiser" arose during this period as a major departure from traditional naval doctrine, in which a large cruiser was armed with battleship-scale guns while retaining only cruiser-rated armor. The tactical concept was that the Battlecruiser could destroy anything within its own size class, while being able to outrun/outmaneuver anything that could seriously damage it. Unfortunately the Admiralty did not grasp the mission concept of the class and usually treated the Battlecruiser as simply a fast battleship with the result being that while they could damage other battleships, they themselves got slaughtered in the line of battle with their lighter armor.

See, though, that the Scharnhorst class shipd (KM Scharnhorst and Gneisenau) are usually classified as Battlecruisers, while the concept (due to Versailles treaty) was just the opposite: battleship armor with main battery (11.1") was among heavy cruiser's (8") and battleships's (12-18")

​

 

[Condottiere]

They're light battleships because of their tonnage in relationship to their era of construction, speed, and relationship of primary armament to hull armour.

 

[kilemall]

See, though, that the Scharnhorst class shipd (KM Scharnhorst and Gneisenau) are usually classified as Battlecruisers, while the concept (due to Versailles treaty) was just the opposite: battleship armor with main battery (11.1") was among heavy cruiser's (8") and battleships's (12-18")

​

Scharnhorst class was designed for 15” guns but went to sea with 11” as a stopgap measure.

 

[aramis]

Scharnhorst class was designed for 15” guns but went to sea with 11” as a stopgap measure.

Functionally, the definitions of ships in WW II are a result of the WNLT (1922) and the 1st (1930) & 2nd (1935) London Naval Limitations Treaty and its 1938 addendum... Which none of the axis participated in..

Anything over 10,000 tons was a capital ship. Anything with big guns (at WNLT and 1LNT 8") was a capital ship.
Anything over 45,000 tons was not allowed...
Iowa Class was originally supposed to come in just under the 45,000 limit and the 2LNLT 16" limit... she missed...

The problem with using the nomeclature from WW II is that it's NOT mission based. It is size/guns based, with alternates for carriers.

 

[Condottiere]

1. The British wanted to shrink tonnage and calibre, mostly because they wanted numbers to patrol all those trade routes; hindsight tells us that Washington and London were mistakes, and they should have just let the Japanese bankrupt themselves trying to keep up.

2. Despite the Anglo Japanese alliance, the British would have been extremely reluctant to go to war with the Americans, and unless the Japanese were facing two or more opponents, could opt out.

3. The lack of numbers of battleships made practically made the heavy cruisers and fleet carriers capital ships, in order to make up for that lost capability, to the point carriers had specific restrictions to gun calibre.

4. The British ship construction time table was off, otherwise they would have had a better balance of force by the beginning of Nineteen Forty.

5. To be fair, their entire arms programme was suppose to be ready by Nineteen Forty Two, and the German one in Nineteen Forty Five.

6. Versailles did work in capping German capacity to build large numbers of large calibre guns; Gustav was a mutant.

7. Diplomatic considerations might have some part in Scharnhorst capabilities in regard to the Royal Navy, but certainly alarmed the French enough to start on the Richelieus.