I've always found it interesting in games to pay attention to what IRL ratings games go with when classifying ships and while I've been able to pick up some sense of the meanings over time from gaming & cultural osmosis and the occasional lazy google, but I always got the sense (& google solidified this sense) that these terms were largely arbitrary & overlapping, or just described a general continuity of scale. But I decided tonight to really sit down & figure out what all is going on, and it turns out that sense was wrong! All of these terms have concrete & distinct meanings, and I find it fascinating and want to share.
So! Origin, usage or how they relate to eachother. In no particular size order;
A) Battleships! Gotta start here, this one's important so bear with me all of this winds up being relevant to other stuff.
The name for the modern "Battleship" comes from "Ship of the Line (Of Battle)". The end of wind sails & ships gaining the ability to sail regardless of the wind heralded the end of broadsiding & line battles, and with them they dropped all but the "battle" part of the name, hence "Battleships". It's actually a little funny, it went from "Ship of the Line (Of Battle)" to "(Ship of the Line of) Battle
ship." It flipped lol. It's important to note that in the pre-modern era nearly every ship built for the express purpose of leaving the coast to make war was a battleship, even if they were small. The only classification below Battleship was Sloop Of War (more on that later). So, for the rest of section A when I say "battleship" I mean "any warship larger than a sloop / with a gundeck", the modern usage of the word "battleship" when applied to pre-modern ships refers specifically to Ships of the Line of the 1st, 2nd & 3rd rating.
1st rate ships were national flagships, 3 full decks of guns
(some had 4 but the 4th deck was basically fake, essentially a PR trick for propaganda. The largest sotl with the most guns ever was a 3-decker). These were so powerful that they always had to be the flagships of their country's defense fleet & couldn't operate with the country's "blue sea navy" -- IE the portion of a country's navy that can sail around the world to wage distant wars. Of note; bc a non-blue sea navy could use coastal craft, and bc a blue sea navy couldn't take the 1st rate battleships with it, that meant that 1st rate battleships were effectively coastal ships. Combine the fact that they were extremely expensive with the fact that they were barely usable for anything, they didn't make many of these.
2nd rate battleships had 2 1/2 gun or 3 decks but couldn't stand up to a 1st rated ship in 1v1. Because these were less important in battles critical to a government's continued existence, these tended to be the flagships of blue sea navies, sailing with invasion or colonial fleets to function as their anchor in large battles.
3rd rate battleships had 2 decks & it was found that as long as the ship doesn't need to be relegated to permanent capital defense (1st) or operate as a flagship for a blue sea navy (2nd), it was always better to run a 3rd rate ship bc they were A) able to go toe-to-toe with any ship that wasn't permanently relegated to capital defense (1st) or blue sea navy flagship (2nd) duty both of which were rarely surprise circumstances, 2) were much, much cheaper to build, C) were much, much faster & less prone to being pinned, outmaneuvered or just abandoned by their own fleet, and 3) bc they didn't have a 3rd deck to make the ship sit lower in the water they were much less likely for a wave to hit the bottom gundeck's open gunports & sink it out of nowhere, which was a thing that kept happening to 1st & 2nd rate ships
which keep in mind were the most expensive ships in a navy.
Battleships of the 4th, 5th & 6th rating (fewer than 2 full gundecks) weren't (or weren't for very long) considered to be Ships Of The Line, & in the advent of a large battle with Ships Of The Line (1 2 & 3rd rated ships) in play would be kept out of the centre of the battle bc they'd get split in half before they could do much, and thus aren't important to the discussion of the (Ship of the Line of) Battle
ship class. And with this the very lengthy but annoyingly important first segment comes to a close and I get to stop talking about ship ratings.
B) Frigates. HAHA JUST KIDDING ABOUT NO MORE RATINGS. Remember how one of the benefits of a 3rd rate ship of the line is that the lack of a third deck meant the ship was far less likely to drop dead instantly for no reason? They figured out that if they built a battleship but instead of giving it 3 or 2 full or even 2 partial gundecks, if they flat out ditch all but the top gundeck they can have a battleship that is almost completely immune to the "our battleship was instakilled by a random wave hitting a gunport" thing bc of how high off the water the guns sit, and thus unlike all other rated battleships were actually capable of operating with all its guns out safely in harsh weather. Importantly, because ships had to have their heaviest guns on the bottom & lightest guns on top, that meant that even if in a storm a frigate went up against a ship with more guns on its top deck than the frigate has, all of the frigate's guns can be heavy cannons while none of the bigger ship's can be, allowing a frigate to situationally punch above its own weight, and bc of how much lighter it is it can usually run away in unfavorable situations.
Because of all these factors, frigates were the ideal setup for battleships operating either in a fleet without ships of the line that needed to avoid combat in unfavourable weather, or operating on their own in roles such as commerce raiding, scouting for a battle fleet, & long ranged cruising. The ship classification is 6th (the lowest) rate battleship, the ship's design is frigate, the ship's operational role is to cruise the open ocean independently.
... wait, cruisi--
C) CRUISERS. A cruiser is a frigate, or what a frigate was. The names split during the interim between the age of sail & the modern naval era, when ironclads were too heavy/slow to perform cruising operations so scouting battleships had to still be wooden frigates, which they slowly started trying to semi-armor with iron internal bulkheads which were called armored cruisers to differentiate them from full wooden frigates that were still able to scout but no longer able to battle and fully armored ironclads that could battle but not scout. Once a wooden hull was no longer needed for a battleship to be able to scout, they dropped the "armored" from "armored cruisers" & just called them "cruisers". So a Cruiser is just a large-ish battleship that instead of being specialized into heavy armament & armor for trading blows to the detriment of its speed & general operating capability, sacrifices heavy armament & armor for increased speed & operating capability.
As a result of this split, with the name frigate being stuck on ships essentially rendered useless in open combat, ships designed to be capable of independant cruising operations but so small that they have to specialize into their role tend to be called frigates (such as missile frigates) whereas ships large enough to be capable of independant cruising operations that are large enough to either be capable of open guns combat and/or are capable of generalized/non-specialized operations as cruisers.
(Interestingly, frigates ceased to be a thing by the time of WW1 bc of being pigeonholed out of being capable of combat, but now there are no more battleships or cruisers (only 2 countries have them, the US & Russia) but frigates have made a comeback because they were pigeonholed out of being capable of combat since open guns-based naval battles aren't a thing anymore)
4) Last one, which is the only one of SS's 4 classifications that doesn't directly stem from Royal British Naval battleship rating doctrine; Destroyers.
In the late era of the age of sail Ships of the Line were becoming so big as to be invincible to gunfire from anything but Ships of the Line of equal or greater size, which were ruinously expensive to operate (& remember, prone to capsizing for no reason). Since the biggest Ships of the Line were generally relegated to coastal capital defense or (again coastal) invasion fleets, it turned out that you could defeat a fleet of Ships of the Line by letting them get to coastal waters and then instead of deploying massive ships to gunfight them, deploy a fleet of tiny ships with bombs to suicide charge them -- a thousand of these boats cost less than 1 Ship of the Line, and it only took a single one of them finding their mark to scuttle a battleship on the spot -- a bomb the size of a boat's entire load capacity set off right against a heavy sea-capable ship's prow will capsize it no matter what (this is still true), more or less regardless of how tiny the boat is. if it holds water out well enough to make it to an enemy battleship then it can hold enough explosives to blow its keel off which instakills any ship capable of open ocean travel.
At first they were fireships, then they became bomb ships, then they started sticking the bomb on the end of a piece of wood so they could pretend it wasn't a suicide mission. Those bombs-on-a-stick were called Torpedoes, and then they attached propellers & engines to them and became what we think of as torpedoes nowadays.
The point was, as battleships became bigger & slower & more invincible to gunfire, there was an increasing prevalence of Torpedo Boats to instakill them, and with them came the need to fight them -- which you couldn't do with the fixed heavy cannons, or even with the light swivel guns way up on the deck of a battleship. So they started deploying fleets of Torpedo Gunboats; tiny boats the size of a Torpedo Boat that could match it in maneuverability & operating conditions, but with a freely maneuverable deck gun instead of a suicide bomb, small enough to mount on what was essentially a raft but still big enough to blow a hole in someone else's raft with a single shot. As the Torpedo Boats got bigger, more expensive, more sophisticated, got sails to go along with their oars, got a closed deck, got an engine, got the ability to launch their charge, got radar, so too did the Torpedo Gunboats along with them. Two "kinds" of ships, of the same size & basically the same equipment, the only difference being which of the two roles they fulfill. And eventually people started to realize -- hey, I'm bringing a fleet of torpedo ships, and also a fleet of torpedo gunships to hunt their torpedo ships. Why are they two different kinds of ship, why not just combine them.
And thus the Destroyer was born. It is a torpedo ship meant to sunder battleships. It is a torpedo gunship meant to screen battleships. Also of note, if you squint really hard, blur ur vision & look past what you see, submarines are also destroyers -- and this tracks when you consider that, the job of a submarine is to hunt enemy keel-bottomed ships and kill enemy vessels trying to do the same thing. And thus, the destroyer gets equipped to destroy submarines too. But mostly, their name refers to their role of fighting other destroyers, oddly enough. And because of how non-specific that role is (basically fight anything ur size), that means that functionally any ship smaller than a cruiser can be a destroyer. The only really concrete discerning factor in what distinguishes a heavy destroyer from a light cruiser is that destroyers arent built to cruise -- in a fleet setting destroyers need destroyer tenders, ships with a high operational capacity to lend some of that capacity to it.
So! That's the origin of all 4 of SS's classes. Frigates and cruisers are the same thing, destroyers should be the smallest class of vessel except that they can't hunt phase ships so really they're more of sloops of war, and everything else is a battleship, unless they have a good logistical profile in which case they're a cruiser (and also a battleship), regardless of size. Wasn't this a productive use of time?
Also, unrelated strictly to SS's 4 classes but relevant to the topic since we're here; what's the difference between a corvette and a sloop and a sloop of war and a brig and a cutter and a schooner and a ketch and a blah blah blah. Turns out the answers are very simple; a sloop of war is any warship smaller than a battleship, all of the rest are
different styles of mast setups that, aside from determining how the ship sails in different wind conditions does little to actually distinguish them from eachother (sloops upwind better than a brig, but either could be bigger than the other), except for a corvette which is just the french name for a small boat. So, if a game uses these names and it doesn't have any wind mechanic then those names are basically meaningless, and if a game implies that a corvette is a different kind of boat than any random name for a small boat in english then it's just talking nonsense.
PS, I used the British Royal Navy classification bc -- well, we're speaking english. Find me another global naval power with a thousand+ years of naval tradition that speaks english & I'll use their system instead
