A Spotter's Guide to Warships of the World Wars

The terminology of ships during the first half of the 20th century is rather confusing, so to explain things, I've put together a pair of glossaries, one for each of the world wars. Each entry will give a sketch of the kind of ship you’d be likely to find under each description. These are not intended to be completely comprehensive, as I just don’t have time. I’m sure my nitpickers valued commenters will be able to come up with all of the cases I missed. I've also written a similar guide to contemporary ships.

• Pre-dreadnought: A battleship built 1889-1905, designed to carry 4 12” guns and ~12 6” guns. Obsolete, but still in service in large numbers. A few may carry some bigger secondary guns in addition to the 6” guns. 12,000-16,000 tons. Speed 18 kts.
• Semi-dreadnought: A battleship built 1900-1910, armed with 4 12” guns and a number of secondary guns bigger than 6”. Obsolete, and not built in numbers as large as the pre-dreadnoughts. 16,000 tons. Speed 18 kts.
• Dreadnought: A battleship built 1905-1914, armed with a larger number of 12” guns (8-10). 10”-12” of armor. Most do not have secondaries bigger than 4”, although a few (mostly German) retain 6” secondaries. 18,000-20,000 tons. Speed 21 kts.
• Super-dreadnought: A battleship built 1910-1920. Armed with guns bigger than 12” (8-12). Secondaries are 4-6”, and armor is increased to match growth in gun size. 22,000-30,000 tons. Speed 21-24 kts.
• Armored Cruiser: A fast ship nearly the size of contemporary battleships, built 1890-1905. Intended for commerce protection or raiding and supporting fleet actions. Usually armed with a mix of 6” guns and larger guns, rarely above 10”. Lighter armor than battleships. Speed 21-23 kts.
• Battlecruiser: The dreadnought equivalent of the armored cruiser, built 1905-1920. The same size as contemporary dreadnoughts, and carrying similar weapons. Early British ones are lightly armored (6-9”), while the Germans are lightly armed. Later British ones approximate a fast battleship. Speed 25-30 kts.
• Light Cruiser: A ship armed with 5-8 4”-6” guns and torpedo tubes, and designed to serve as a scout, trade protector, and general fleet utility vessel. 2-3” of armor. Built 1905-1920. 4,000-5,000 tons. 29 kts.
• Destroyer or Torpedo Boat: A small ship designed to launch torpedo attacks and fight other torpedo craft. 900-1100 tons. No armor. 4 4” or 88mm guns and torpedo tubes (3-12). Built 1910-1920. 33 kts.
• Submarine: A surface ship that can temporarily submerge to evade detection. No, that isn’t a typo. A WWI submarine can be best thought of as a submersible surface ship. It could do about 15 kts on the surface and about 8 kts submerged, maybe a bit faster. 4-5 torpedo tubes, 1 gun. 500-800 tons.
• Escort/Sloop/Minesweeper: An auxiliary warship for sweeping mines and patrolling or protecting convoys. 500-1200 tons, with a couple of medium guns and minesweeping equipment. May carry a few depth charges, or an explosive paravane system. 16-18 kts.
• Seaplane Carrier: A ship, usually a converted merchantman, that carries seaplanes. Usually a dozen or so, but each one is unique. Most fly the planes off from the ship, then recover them from the water.
• Armed Merchant Cruiser/Raider: A merchant ship, usually an ocean liner or a fast cargo ship, modified into a light warhip. Fast, long-range, with good seakeeping. Usually a few 6” guns. Speed varies greatly. Used for escort work and patrols, sometimes as a commerce raider.

• Battleship, Pre-Treaty: See Super-Dreadnought, above. Anti-aircraft guns have been improved, and deck protection might have been increased as well.
• Battleship, Treaty: A battleship built after 1930, under the auspices of the Washington Naval Treaty. 35,000 tons standard. Carries 8 or 9 guns of 14”, 15”, or 16”, with heavy anti-surface and anti-air secondaries. 12-14” of belt armor, good horizontal protection. 27 kts.
• Battleship, Post-Treaty: A battleship built after 1936, not under the auspices of the Washington Naval Treaty. 40,000-70,000 tons. 8 or 9 guns of 15-18”. 12-16” of belt armor. 27-33 kts.
• Aircraft Carrier: Either a conversion of a battleship or battlecruiser cancelled under the treaty, built in the mid-20s, or a new-build ship from 1930 on. 18,000-37,000 tons. Some carried up to 8” guns, but most have 5” guns and light AA guns. 50-90 aircraft, depending on configuration and loadout. Most are unarmored, but the British armored theirs (resulting in low aircraft loadouts.) 30-33 kts.
• Carrier, Light: An austere carrier constructed quickly in wartime (1943-1945). 10,000-13,000 tons. Light AA guns only. 36 aircraft, unarmored. 25-31 kts.
• Carrier, Escort: A slow, small carrier built to escort convoys and provide air support for amphibious landings. Built 1941-1945. Very light armament. 27-33 airplanes. 16-20 kts.
• Large Cruiser/Light Battleship: A group of odd ships. Around 25,000 tons, armed with 11-13” guns. Built in the 30s and another batch in the mid-40s. Built for special reasons, and none were particularly successful. 30-33 kts.
• Heavy Cruiser: A category created by the Washington Naval Treaty, 1925-1945. Most were 10,000 tons standard, rising to 15,000 tons for some wartime ships. Armed with 8” guns, usually 8 or 9. Lightly armored (3-6”), and often referred to as ‘tinclads’. 4-5” AA armament, sometimes torpedo tubes. 32 kts.
• Light Cruiser: A creation of the London Treaty of 1930. 1932-1945. 7,000-11,000 tons, 8-15 6” guns. Otherwise, very similar to heavy cruisers in armor and secondary armament. 33 kts.
• AA Cruiser: Another creation of the treaties. 1939-1945. 6,000 tons, and armed with 10-16 5” guns, the standard dual-purpose armament of contemporary battleships. 3” armor. Light AA guns, torpedo tubes. 32.5 kts.
• Destroyer, WWI: A leftover destroyer from 1917-1920. Used primarily as an escort. 1090-1200 tons. As built: 4 4” guns, torpedo tubes, and depth charges, 34 kts. Many modified with more AA guns and ASW weapons, often with reduced speed and increased endurance.
• Destroyer, Standard: A destroyer built 1927-1945, used for every purpose at sea, most notably ASW and AA screening. 1300-1700 tons. 4-5 DP (dual-purpose) guns of 4.7-5”. Light AA guns, 8-16 torpedo tubes, and depth charges. 37 kts.
• Destroyer, Large: A destroyer built 1930-1945. 2000-2600 tons. A bigger, better-armed version of the standard destroyer, often with greatly increased range. 5-8 DP guns of 4.7-5”. More light AA guns, 8-16 torpedo tubes, and depth charges. 38 kts.
• Destroyer Escort/Frigate: A mass-production escort built 1939-1945 as a war emergency escort ship for slow groups. 1000-1500 tons. 2-4 3”-5” AA or DP guns, 2-3 torpedoes, and extensive ASW armament. 20-28 kts.
• Submarine, Small: Another submersible surface ship, small and relatively short-ranged, although the Germans used them throughout the Atlantic. Built 1930-1945. 600-700 tons, 4-5 torpedo tubes, 1 deck gun, light AA guns. 17 kts surfaced, 9 submerged.
• Submarine, Large: A bigger, longer-ranged submarine. Built 1930-1945. 1300-1800 tons, 10 torpedo tubes, 1-2 deck guns, light AA guns. 15-21 kts surfaced, 9 submerged.
• Corvette/Sub-chaser: A small ship designed as a light escort, hopefully for coastal waters, although many were employed in the Atlantic. Built 1940-1944, 800-950 tons. 1 3”-4” gun, light AA, depth charges/ASW weapons. 16 kts.
• Minesweeper: A ship designed to remove mines by sweeping them up with cables towed alongside. Built 1937-1945, 800-950 tons. 1-2 3”-4” guns, light AA, some depth charges, minesweeping equipment. 17 kts.
• Motor Torpedo Boat/PT Boat: A speedboat fitted to carry torpedoes. An excellent place to put dashing young officers who are not suitable for real work. Otherwise mostly useless. Built 1939-1945, 30-55 tons. 4 torpedo tubes, light AA guns. 39 kts.
• Armed Merchant Cruiser/Raider: A merchant ship, usually an ocean liner or a fast cargo ship, modified into a light warhip. Fast, long-range, with good seakeeping. Usually a few 6” guns and AA armament. Speed varies greatly. Used for escort work and patrols, sometimes as a commerce raider.
• Coastal Defense Ship: A ship designed to protect a country's coast. Built 1900-1940, 2000-6000 tons. 2-4 heavy guns, some lighter armament. 10-15 kts.
• Monitor: A ship intended for coastal bombardment. Built 1915-1942. 6000-10000 tons. 1-2 guns of 9.2-18". Heavy underwater protection. 6-12 kts.

This is already quite a long list, so I'm going to leave auxiliaries and amphibious shipping off of it. I've discussed them both at some length elsewhere.