And with culture. What you say is eminently true for recent history and current state of affairs on Earth today. But the Imperium isn't just the 21st Century transposed to the 57th, is it? The Imperial Navy isn't just the Royal Navy in Space, is it?
I repeat, in the 3rd Imperium, 'cruiser' is the term used for a ship big enough to mount a spinal mount but unable to stand in the line of battle. Nothing to do with its role. Well... no doubt the term derived from the fact that cruisers are often used to cruise.
Hans
Oh my, I seem to have sparked another one of those "what kind of ship/navy is the OTU ships/Navy analogous to in current Earth history" arguments. Sorry about that...
I agree with Whipsnade on this: names of classes, and what those classes are used for haven't had a lot to do with tonnage since the development of reliable missiles for naval warfare. I wold argue it's more having to do with tradition and whatever givne mission that ship type is equipped to do - and a lot of them seem pretty much equipped to do a lot of different roles. At least the non-carrier types.
A cruiser now just seems like a big destroyer that has more missiles and more C3 capability. But in some navies the destroyer is more like a cruiser since it carries really large missiles. And anything that can carry a large enough missile can carry a nuclear one, too, so how does that fit into the traditional definitions? And nobody uses lines of battle or armor anymore.
And BTW: I keep pointing out that I have my own TU and it was developed long before all this 3I stuff and even before HG2 came out. So I have my own design specs. Imperial Navy destroyers range from 20-50kt, cruisers from there up to about 80kt, and battle ships average around 100-150kt. Carriers are rare but the 6 that exist are 250kt and are more of a combination carrier/flag/battle ship. They each form the core of one of the fleets. There are myriad smaller ships, and ones in between. And any capital ship is one that is cruiser on up and has a jump drive. Anything w/out a jump drive and/or smaller is just a ship. The Terran Imperials don't use battleriders, but their enemy does.
Destroyers tend to be more missile heavy but that's because they have a landing support role - which is a big part of the reason for the spinal meson guns in some of them: to pound the heck out of the ground defenses prior to landing. The missile bays salvo nuclear strikes on the surface troops while the big meson guns hit the deep meson batteries of the enemy. Since the bigger ships have probably cleared the way already, the spinal meson gun-equipped destroyers can then attack the ground emplacements while the jump troops can start dropping in. They don't have to be agile so much as just cheaper than a cruiser+ and have the juice to use a meson J or N gun.
And all that tends to be just background color. The players are small fish that swim in the shadows of the Imperial Fleet Great Whites ... the authorities they mainly deal with are the small-ship universe types of the Colonial Fleet: the biggest is 5000 tons and the average is just your regular 800 ton cruiser from LBB2. I use a two-tiered system of HG for the serious big events that the players try to stay away from and LBB2 for the player adventure stuff. If an Imperial squadron jumps in-system and the players attracted its attention, well, they must have done something realllllly bad.