Naval terminology for vessel types was based on function, not size, and the size could vary widely depending on technology. At that, the function often changed over time. Sometimes the name of an obsolete function was borrowed to describe a new function. The following is a short history, based mostly on English/American practice. In other languages different names with different shades of meaning occur, and fashions change (like replacing the Dutch sloop with the French corvette. some navies use numerical catagories like the 6 English "rates" or the French 1st, 2nd, and 3rd class cruisers. And this is not even taking into account Vilani Naval traditions.
And there are new names. From submarines we get "hunter-killers and "boomers." "Arsenal ships" and "Sea Control Ships" are proposed new classes of ship. There is a whole range of Air Force adjectives like "attack," "strike," "stategic," "air superiority," "air domination" (that's new, for the F22) or even the old "pursuit."
Also, the use of certain names in media tend to become mainstream. For example, the F16 was known to its pilots as the "Viper" from Battlestar Galactica. Star Wars call their capital ships "destroyers," and five hundred years from now that is more likely to be remembered than the Fletcher class tin can. Deathstar might even be the new word for "dreadnaught." All in all, I think you can justify just about any name class you want.
Now, the boring history lesson.
Sloops, Corvettes, and Destroyer Escorts
A Sloop is a fast sail boat with one mast and triangular sails, but in Naval usage it refers to a small ship (400-1000 tons), usually square rigged. It was usually to small for a Captain and only had a Commander in charge. Corvette was the French word for the same ship. In the middle of the 19th century steam replaced sail, and the larger sloops (1000-2000 tons) became "Corvettes" or even "Armored Corvettes" in most Navies. Around WWI small ships were commissioned to escort merchant ships. These were called "escorts" "sloop escorts" or "corvette escorts." The US Navy eventually settled on "destroyer escort" (although they kinda tend to "Frigate") while the rest of the world uses "corvette."
So this class of ship went from being an 400 ton independent patrol ship to a 4000 ton herder of merchantmen.
Frigates
At the end of the age of sail Frigates were three-masted, square rigged, 1000-2000 ton warships with one gun deck. This made them faster and more maneuverable than the ships-of-the-line, which had two or three gun decks. In fact some of the biggest Frigates were "razzees" made by cutting off the upper decks from a ship-of-the line. The American Constitution class were just as big, better armed, and set the standard for the next fifty years. When steam power came in Frigates first had paddle wheels, then screws, and they grew to 3500 tons. The term fell out of use for a long time, replaced by Cruisers, but in the 1960s a class of big guided-missile destroyers were briefly called "Frigates" before being reclassified as "Cruisers." Since WWII "Frigate" has been used by most Navies to describe a Destroyer-class vessel with a dedicated ASW mission.
So Frigates went from being the 1000 ton far-ranging eyes and ears of the fleet and commerce raiders, the ideal berth for a man of ambition, to part of the main battle fleet and held tight to screen a particular threat.
Destroyer
The wonder-weapon of the late 19th century was the Whitehead self-propelled torpedo. High speed boats could dash in on battleships to fast for the main battery to target them and release the torpedo before the rapid fire guns could engage them. To prevent these attacks a class of small (600-1000 ton) fast ships armed with rapid fire guns were built: the Torpedo Boat Destroyers. Ironically, these ships proved to be better at making torpedo attacks than torpedo boats, so the boats were retired and every fleet bought Destroyers. Destroyers gradually absorbed anti submarine and anti-aircraft missions and grew to 2000 tons in WWII and today are 9000 tons multi-mission ships. In the US Navy today, the difference between a cruiser and a detroyer is barely a hairbreadth.
Well, Destroyers started out as 600 ton ships screening the battlefleet from a very specific threat, and they are now much 9000 ton ships shielding the fleet from all threats.
Cruiser
In the early steam era sloops, corvettes, and frigates were considered "cruising ships" because they were intended to cruise around patrol areas. By the late 19th century, these classes were generally replaced by different types of "cruiser." The Scout Cruiser was a fast, lightly armed and unarmored vessel of about 1700 tons., the Protected Cruiser was about 3500 tons and the Armored cruiser nearly a battleship at 7000 tons.
During WWI cruisers were divided into heavy cruisers (14000 T) and light cruisers (7000 T). By WWII heavy cruisers were17000 tons (with 200 mm guns) and light cruisers 12000 tons (with 120-150 mm guns). By late in the war, American cruisers were primarily anti-aircraft platforms and eventually became missile platforms with advanced radar used to escort carrier battle groups. By contrast, post-WWII Soviet Cruisers became their primary ship-to-ship platform, using cruise missiles.
So cruisers started as 1500 ton "lone wolfs" patrolling the seas and protecting shipping. They have ended up as 15000 ton parts of the main battlefleet under the watchful eye of an Admiral.
Battleships, Dreadnaughts and Battle Cruisers
The Ship-of-the line was a sailing vessel of about 2500-3500 tons, with multiple gun decks. In the middle of the 19th century large ships were given steam power, and armor, and these "armored ships" got up to 6000 tons. Eventually, they grew to over 10,000 tons with mixed batteries (say 150mm, 230mm, and 300mm) of high explosive shells guns, the first "battleships." In the early 20th century a new generation of large (20-30,000 ton), fast, battleships with a main battery of all big (300mm+) guns that simplified fire control. These "Dreadnaughts" obsoleted all other battleships. By WWII battleship had grown to 40-60,000 tons with a main battery of 400mm or more but it was used to screen carrier groups or to support amphibious attacks. Since WWII, only the United States has had battleships in commission.
The in the Dreadnaught era, the British designed (and lots of people emulated) Battlecruisers that were as big as or bigger than battleships and as well armed as battleships but with light armor and high speed. They were supposed to blind an enemy fleet by destroying the enemy's cruiser screen, but they were easily destroyed when they tried to fight real battleships. The Hood is famous, but the same thing happened over and over at Jutland.
These started as 3000 ton main-force ships, defining a nations fleet. They gradually got more and more powerful (up to 60,000 tons), but eventually were superceded by aircraft carriers and vanished from economic pressure.
[This message has been edited by Uncle Bob (edited 09 May 2001).]
