"When you began, you couldn’t have possessed enough bones for the whole ship. It would look stupid with a few dozen skeletons nailed to the walls. So, how do you start? Do you save up enough bodies for a corridor at a time, or put them away until you have enough to decorate the entire vessel?’"
- – Jain Zar,-Storm of Silence
The Imperial Navy is one of the main branches of the Imperial military in Warhammer 40,000 (although very little of the Navy actually appears in the tabletop game). They are also one of the main factions in the beloved spin-off game Battlefleet Gothic.
Unlike the Imperial Guard, who get killed in the
thousands millions billions every day, the Imperial Navy rarely suffers that many casualties. This is because, unlike the flashlight used by Guardsmen, the main weapon of the Navy is a giant, heavily-armed, heavily-armored battleship that puts other races' spaceships to shame (well, except Necrons). These ships are also massive, flying, Gothic cathedrals.
Depending on how you look at it (and who you're looking at), the officers of the Navy are either wealthy cowards or badass gentlemen. In either case, their ships have crews numbering the hundreds of thousands or even millions (we're not kidding when we say that each ship has its own language(s) and culture(s)), since the Imperial Navy doesn't understand how auto-loaders work, so loading a gun requires thousands of slaves running on treadmills. Of course, this might be the fault of a certain other branch of the Imperium, who, coincidentally, do have working auto-loaders on their ships. In any case, the Imperium has found it cheaper and more effective to use manpower because they have that many people to throw at even the tiniest of problems. Of course, for a major officer, most days simply require him to press a button and blow something up, then go back to drinking his tea. Oh, and maybe scramble the ground-support flyers, if he's feeling charitable that day.
Note that, back in the Great Crusade, the Imperial Guard and Imperial Navy were one and the same, operating under the far-less-badass name of "Imperial Army." However, thanks to the Horus Heresy, the two got split up, so that a single military commander couldn't control too many forces; a Guard commander isn't able to get off any given planet without the Navy, and the Navy isn't able to conduct wars (and, you know, occupy territory) without the Guard. (And neither can do their job without the Adeptus Munitorum giving them fuel and ammo. Thanks, Bobby!) You'd think that this enforced mutual co-dependence would make them collaborate, but of course, despite how much they need each other, the two bicker constantly, which, in fact, may be the reason for all the stupidity the 40k universe is saddled with.
- 1 Types of Ships
- 2 Important Details
- 3 Ranks in the Navy
- 4 Notable Problems
- 5 Music of the Imperial Navy
- 6 External Links
- 7 Gallery
Types of Ships
The Imperial Navy has four types of ships they hide their cowardly asses in. The main ships are battleships, cruisers, escorts, and fighters
Supposedly rare, but every Grand Marshal and High Admiral has at least one and often several or even dozens to hide in because GW is completely and hopelessly inconsistent with fleet sizes, though as of late it seems that GW is leaning towards big fleets and big armies when it gives numbers. Bonus points if that coward is also Chaos. The biggest heaviest hitters available, these things are like actual medieval cathedrals in that the grandchildren of the workers who start building them get to live to see their completion. Fuckheug, lots (and lots, and lots) of guns and most can deploy fighters and bombers.
- Retribution: Packing all gun batteries, the ship can devastate an entire continent in one broadside, but for some reason cannot destroy a hive city or fort with void shields - or in some cases, ones without any shields at all; either that or GW was just pulling another Michael Bay out of their asses again since, they have no idea how consistency works, let alone basic physics. Of course, considering the Dark Angels fortress-monastery and the huge chunk of land surrounding it survived the bombardment which turned Caliban into a bunch of space dust, it is perfectly reasonable that something that merely glasses half a continent would not destroy a void shielded city or other major fortification. If anything, this provides a degree of insight into why land battles in 40k are so massive in the first place. Because orbital artillery doesn't have many targets of opportunity it is actually capable of exploiting.
- Invincible: An interesting class, dubbed a 'fast battleship', these were designed to chase down xenos and chaos raiders, and then use them to make the vast, empty tracts of space more interesting by filling it with their enemies' debris fields. This type of battleship combines the firepower of a Retribution with the speed of a Dauntless. The problem with this is the general incompetence of Imperial tacticians. It looks exactly like a Retribution and has the guns to match, so it must be one, right? NO. They excelled at the role they were designed for, but throw them into gunfights against dedicated battleships, and these things tended to come apart easier than wet cardboard, earning them the nickname 'Kisher's Kombustibles' and the scorn of many admirals. Admirals who ignored the fact that the reports detailing the introduction of the ship and how to best use it (it's tactics also included in the Tactica Imperialis) explicitly state not to use it on a gun-line and that it is for fast-ship interdiction. The ship's Commissars must be particularly incompetent to let this slide as in the Guard the generals would be executed quickly for such incompetence. Of course, these are also the Commissars who do nothing when troop transports' escorts frequently run off to fight while the transports lose a significant percentage of their ships. Perhaps if they would actually enforce their orders to stay with the transports, the Imperium would have won most of the campaigns it has lost. Given that they still often win even with a fraction of their beginning ground forces actually managing to make landfall. Because they have THAT many men to throw at the enemy.
- Much like the Chalice-class of Battlecruisers, the Invincibles are a big reference to the real life Battlecruisers of World War 1, especially with the term "Kisher's Kombustibles" (real life Battlecruisers were referred to as "Fisher's Combustibles") and the fact that three blew up in a single battle (referencing Jutland).
- Apocalypse: One of the oldest ship designs (predating the Retribution, which is also one of the oldest ship designs), this ship packs a lot of lances and a Nova Cannon. Good for taking out lots of smaller sized ships with massed lance fire. It's also described in fluff as being able to cripple anything up to a cruiser with a single, concentrated broadside. They're fairly rare, since the Imperium doesn't know how to build them anymore, and the ones still operating are so old, their weapons systems have degraded permanently, forcing them to fire their lances at only a fraction of their full power. Shares all the disadvantages of a Gothic-class cruiser.
- Victory: Possibly an attempt to recreate the Apocalypse class, the Victory is basically a Retribution with a bunch of lances replacing its broadside cannons, and a Nova Cannon instead of torpedoes. Has the range that fluff states the Apocalypses once had, but lacks the same level of firepower. Effective at sniping, and hilarious when used against escort heavy fleets.
- Desolator: A ridiculously old design. Designed to emphasize range and carries Torpedos, Broadside Lances and Dorsal Macrobatteries. Like most keel-built ships, the Desolators ended up mothballed or went traitor.
- Emperor: The "standard" battleship of the 40k 'verse, the ship has multiple fighter decks and weapons batteries. Unfortunately, most commanders like to use this ship as a hideout, causing the lack of sufficient air support in the ground wars even though the Navy's atmospheric aircraft are completely different from its much bigger space based strike craft. Tabletop-wise, its status as the official battleship of Battlefleet Gothic doesn't stop it from losing carrier duels against the Chaos equivalent.
- Ironically, the idea of the Emperor being the standard battleship conflicts with the fluff about the Navy hating Carriers. Go figure.
- Nemesis: The super-carrier of the Imperial Navy. It has SIX flight decks (the size of towns or small cities, each), more than any other ship in the galaxy. But because of Rule of Cool, it is incredibly rare since the Navy captains prefer to get up close broadside their enemies, or actually rather because all of the ships in this class were just ships modified from Emperor class ships in one particular war, because they were damaged or otherwise. Naturally, the Navy never considers making them based on the Invincible instead (the Invincible was mass-produced).
- Desecrator: The carrier variant of the Despoiler. Replaces half the Broadside Lances with Landing Bays. Shared the same fate as its sister class and is now only seen in Chaos fleets. Traitorous despite its clearly pious and Emperor-loving name.
- Despoiler: Oh boy, where do we start? The Despoiler-class came about after the cogboys discovered plans for a carrier on Barbarus. The catch? Well, Barbarus is the former homeworld of the Death Guard, and the plans were for the same class of ship that the Terminus Est is a part of. Showing a complete lack of common sense, the Imperial Navy decided to build ships of this class, only for them all to go traitor due to the class's inherent Gellar Field flaws. Oops. The Despoilers at first don't appear to be that unique, as they have Dorsal Lances and Broadside Landing Bays and Weapons Batteries. Their difference is that, like the Terminus Est, they managed to have a Prow Landing Bay as well.
- Despite being a new class, GW fucked up their fluff and had Rogal Dorn disappear aboard a Despoiler, 5000 years before the class was created. Note this class was actually already named "Despoiler-class" by the Imperium. Yet, they were surprised the things went traitor. Wow. Also, after fixing the Gellar Field problem, the Imperium still decided not to build more, which was stupid since there was no longer a reason not to. I get not wanting to chance it, but beggars can't be choosers.
- Emperor: The "standard" battleship of the 40k 'verse, the ship has multiple fighter decks and weapons batteries. Unfortunately, most commanders like to use this ship as a hideout, causing the lack of sufficient air support in the ground wars even though the Navy's atmospheric aircraft are completely different from its much bigger space based strike craft. Tabletop-wise, its status as the official battleship of Battlefleet Gothic doesn't stop it from losing carrier duels against the Chaos equivalent.
- Aircraft: As part of the reforms falling the Horus Heresy the Imperial army was not just split into regiments to insure that no one imperial army could be self sufficient if it fell to heresy or rebellion, the army was also split from it's air power which was given to the Imperial navy. Strictly speaking all atmospheric aircraft are also part of the Imperial Navy, with only a few general exceptions.
- Gloriana: Massive, terrifying and capable of decimating entire fleets on their own, these were the personal flagships of the Primarchs during the Great Crusade. Very few, if any, are still around in the Imperium in M41, though a few such as Horus's flagship Vengeful Spirit are still tooling around inside the Eye of Terror. Because they were dickheads, the Alpha Legion had two, creatively named the Alpha and the Beta. Interestingly, the Ultramarines have one, the Macragge's Honour, but didn't fucking use it, the whole fucking time until Roboute Guilliman returned. It shows up again in Dark Imperium, with the Smurfs having stolen it back from the Red Corsairs, which at least is fucking funny even if it makes no sense. The Imperial Fist had the Eternal Crusader, but it was never their flagship since the Phalanx is so much better, so Rogal Dorn gave it to the Black Templars in the Second Founding. The Emperor is known to have had at least one, called the Bucephalus, which he ditched after upgrading to an enormous golden space palace called Imperator Somnium. Wait, did Emps just see the Phalanx and decide to build his own bigger better version?! DICK
- Oberon: The mixed-breed bastard of the Imperial Navy. It has lances, fighter bays, and weapon batteries. Its a powerful ship...
when fighting foes half its size"Newer" fluff says the Oberon is rare, but a complete success in making a ship capable of killing anything it comes across, alone. Unfortunately, fluff also says a ridiculously low number of these (apparently) powerful ships were made (like, 3 or so). Then again: only four Iowa class battleships ships were built (technically 6, but 2 were scrapped before completion), and we know HOW to build them. It makes sense in a way. Attack craft can cripple an enemy's main weapons and engines and likely ultimately damage the power transfer from generators to void shields. Combined with macro-batteries hammering away and the enemy's weakened ability to maintain its shields would cause them to drop much quicker than usual. Then the city-sized lance-batteries rip the enemy in half. If used against enemy escorts to support attacks on large enemy ships like battleships and grandcruisers, this would work extremely well to the point an Oberon would likely become a priority target for enemy ships.
Only slightly weaker and less powerful than Battleships, Grand Cruisers were the Battlecruisers of the ancient Imperium (modern Battlecruisers are simply outclassed by these venerable vessels). Nowadays most of them run on archeotech that is barely understood and hard to repair with current Imperial knowledge. These grand ships are often used as flagships in lieu of extremely rare Battleships. Basically, they are the quintessential Battlecruisers; tougher and deadlier than Cruisers and yet more mobile than Battleships.
- Vengeance/Furious: The granddaddy of "modern" Imperial warships. The Vengeance was the winner of a GW-sponsored ship design contest, and was originally known as the Furious. Highlights include heavy shielding and armour (though lacking the prow armour of later designs), as well as both lances and long range weapons batteries, making this the sniper of the Imperium's Grand Cruisers.
- Repulsive: Originally named the Corinatus Class, before being renamed after many fell to Chaos by an overly literal Mechanicum designation. Whilst the Repulsive Grand Cruisers are exceedingly maneuverable heavy warships (and therefore exceedingly useful because they can fill a hole in the Imperial tactical lineup), they are considered a cursed class due to the majority of them falling to chaos, which unfortunately was the result of experimental warp drives which occasionally interfered with the Gellar Field (OMGWTFBBQTIME). Only the Emperor knows what kind of complete moron would deploy ships equipped with that. The ones that remain in Imperial control are kept mothballed in reserve fleets and segmentum fortresses (imagine giant glass boxes with 'In Case of Emergency, Break Glass' signs). It doesn't say anything about their warp drives being swapped out for something that isn't shitty or perhaps a completed and no longer experimental version of their own.
- Avenger: The short range brawler of the Imperium's Grand Cruisers, it's a Vengeance with only macrobatteries (kilometres of Macrobattery broadsides). Intended to break the line of battle like Nelson's ships at Trafalgar, while suffering from the lack of an armored prow. Unfortunately line-breaking is quite a dangerous role for any ship, even a Grand Cruiser that excels at doing it, and so not many exist in the 41st Millennium. Those that have survived are known for being exceedingly reliable and faithful; it takes a lot of damage or mistreatment to cause these noble vessels to give trouble. If you spoke with members of the Imperium (both members of the public and the navy), this is the vessel they would think of if you asked them about Grand Cruisers. Now, if only the Imperium realized a slower but more heavily armored and shielded ship would fare better in its role.
- Executor: The sniper of the Vengeances, the Executor replaces its Broadside Macrobatteries with even more Lances. Unfortunately, the last remaining Imperial Executors decided to act retarded and chase a fleet into the Eye of Terror, meaning that all of the ships are chaos aligned now.
- Exorcist: A Vengeance that has carrier bays in place of lances. Useful in providing carrier support to any Imperial fleet. As a bonus, being Grand Cuisers mean they can outrun anything except battleships to save their vulnerable carrier self while their attack craft are away. Originally designed for extended operations alone on the Frontiers of Imperial Space, either on Patrol or by exploring into the unknown, the Exorcist developed quite a reputation for 'boldly going where no man has gone before'. Whilst not many remain in Imperial Service due to maintenance difficulties, they still find use in the hands of Rogue Traders who need vessels capable of long cruises and of defending themselves against anything they might encounter. So much for maintenance difficulties.
- Retaliator: A mix of a Repulsive and a Vengeance, but as a Carrier. Has Lances, Launch Bays and Macrobatteries on its Broadsides. Unfortunately, it has the Repulsive's tendency to go traitor.
What do you do when you forget how to maintain an entire category of heavy warships? You build a new bunch of heavy warships, with simpler technology.
Battlecruisers are basically upgunned cruisers, with more weapons (usually adding dorsal weapons and some armor), and are intended to fill the gap between true battleships, which are rare, and normal cruisers, which tend to die really easily to the ancient Chaos cruisers and grand cruisers. Battle cruisers were tried in real life as some way to combine battleship firepower or armor and cruiser speed. They did not always work, and much like reality these things have their share of problems. Chaos operates their own versions known as Heavy Cruisers.
- Armageddon Battlecruiser: An upgraded variant of the Lunar Class Cruiser (YAY! ANOTHER ONE!). A rather new innovation, the Armageddon class is basically made up from recovered Lunar Class Hulks that have been extensively repaired and then retrofitted with more armour and more weapons. The base hull was never designed to cope with all this extra equipment (and the extra crew to man said equipment) and so it has problems operating independently for long periods of time. This isn’t really a problem, though, since they wouldn’t be operating away from a fleet anyway. Though reinforcing its frame to handle the added mass would be a smart thing to do to save immensely in future maintenace costs over the centuries. Battlefleets won't say no to them because more guns = better!
- Hellfire Heavy Cruiser: An upgunned Murder-class. Has the same issues as the Armageddon, slow as fuck and has power and supply issues. Also, lacks Void Shields. Most mutinied and joined Chaos, which decided to use them for some reason.
- Overlord Battlecruiser: The Classic Imperial Battlecruiser. Using the standard Imperial doctrine of - Macrobatteries, Lances and Torpedoes, the Overlord has become the most effective Battlecruiser simply because it really complements standard Imperial Navy Tactics. As an added bonus, its simplicity of design makes it easier to produce and one can be built within a decade. The only negative (if you can call it a negative), is that it's not really useful for anything except war.
- Chalice Battlecruiser: A fast heavy cruiser. Unique to the Calixis sector and an exceedingly new design, the Chalice was conceived as a Battlecruiser that could either out-run or out-manoeuvre anything it can't kill. Which means it was conceived to be a plain ‘ol normal battlecruiser. Whilst good in theory, unfortunately, speed came at the cost of armour and durability and so whilst these vessels punch hard, they can't take as many hits as other cruisers. In addition, it carries an experimental plasma drive layout, which while boosting power efficiency, also makes it rather vulnerable to lighting up like a roman candle. Imperial Propaganda is currently trying to cover up their failings and is lauding them as the Poster-ships of the Calixis Sector and therefore a lot of people think they're the 'Best Battlecruisers Eva!'. If they would just use a normal plasma drive and make the whole ship bigger, it would be fast enough, armored enough, and even better armed. Unfortunately, not being stupid is heresy in Calixis.
- The idea of a ship that can "either out-run or out-manoeuvre anything it can't kill" that turns out to be really poor at taking hits was the original design of real life Battlecruisers, which although being up-gunned Cruisers (which are the equivalent of Frigates IRL, not Ships of the Line), were used as discount Battleships at Jutland were they turned out to lack the armour required for a proper fight. Thus, if the Imperials were smart, they would be using the Chalice as a commerce raider, not a ship of the line.
- Long Serpent Battlecruiser: A true success story, this is what the Chalice wishes it was. Taking a battlecruiser's armour and firepower, and giving it the engine suite of a battleship, this thing can kick the shit out of anything short of a grand cruiser or battleship, while being able to keep up with raiders. It's only real flaw is that when one is taken out, it has a better than average chance of rupturing its warp drive. As a result, the names of Long Serpents that have been destroyed are usually accompanied by those of allied ships that were too close. Which is somewhat odd since the reasoning is that the Long Serpent also has a battleship's warp core (who knows why, it isn't big enough to need it). Given the small difference in size between this ship and other "normal" cruisers which are the mainstays of the fleet, the Imperium could just choose to use a smaller warp core suitable for this ship's size and focus on mass-producing the Long Serpent to replace basically every other class of ship except battleships , Cobras, and carriers. Fewer would be made but, unlike video games, swarming a capital ship with escorts does not work at all. The escorts are slaughtered and the capital ship like this one is left unharmed. But doing this would require common sense, which is Heresy. Like properly using the Invincible-class must be.
- Mercury Battlecruiser: Another fast Battlecruiser. It's a cruiser with a Battleships's engines. Nothing more.
- Hades Heavy Cruiser: A long-ranged brawler. Carries Broadside Macrobatteries and Dorsal and Prow Lances. Got phased out like most keel-built designs, but Chaos still uses them.
- Acheron Heavy Cruiser: Designed to test new Lances and Macrobatteries. The Imperials only built one, which went traitor. Carries Broadside and Dorsal Lances with Prow Macrobatteries.
- Mars Battlecruiser: In a word - Mediocre. Some Imperials say it's versatile due to its diverse weapons loadout but in reality it makes it an awkward duckling to use. The Nova Cannon and Launch bays would be good on a ship holding back and harassing enemies at range and yet it has Macrobatteries and Lances which are great for brawling. So if you sit back and harass or go in and brawl, you're wasting half your ship. The Imperial Navy never really got on with it either and so it has gone out of production on most Forge-Worlds. Which is a shame because if they would replace the macrobatteries and lances with larger, long-range lances, and a great number of small, short range weapons batteries for fighter support and self-defense respectively, this would be a great ship in any fleet. It's nova cannon clears a hole in the enemy escort screen, the attack craft rush through to wreck the weapons and engines of light capital ships while long-range lances assist other Imperial ships in slaughtering targets of opportunity. The destroyed enemy light capital ships leaves all the other big ships vulnerable to mass, concentrated torpedo attack from friendly ships. Attack craft return to the fight to tear up the no-doubt seriously damaged enemy big ships and lances win the day. Then just send in friendly light capital ships with attack craft support to finish off the surviving escorts. That would almost make this ship into a sort of miniature "I Win" button. Almost. Especially in a squadron of two, as they could assist each other against any opponents that slip through to them with their combined, close-range firepower, lances, and whatever attack craft they kept back for defense ripping the enemy weapons and engines apart to let the close-range macrobatteries have fun.
- Dominion Battlecruiser: Basically a fixed Mars, some tech priest got it in their head that, maybe, it'd make more sense to replace the Macrobatteries with Lance Batteries instead, making it a dedicated support ship, harrassing enemy ships at range whilst the big guns go out and fight. Apparently not that successful, a number were used at the Battle for Maccrage (Of course the fucking Smurfs get them) against the tyranids, though apparently they all got fucked up and have been in drydock since, which is why up until now no-one's seen them.
- Styx Heavy Cruiser: A pure carrier. Has Broadside Launch Bays, Dorsal Lances and and Prow Macrobatteries. For some reason the Imperial phased it out for the Mars, so only Chaos uses them now.
- Hecate Heavy Cruiser: An attempt to replace the Styx. Swaps out some of the Launch Bays for Macrobatteries. Believed to have an inherent design flaw that made them go traitor, so they were decommissioned.
Cruisers are the bread and butter of the Imperial Navy. Much larger than escorts and light cruisers, but less rare than battleships, cruisers are what the Imperial Navy (and Chaos and Xenos) use to fight their campaigns across the stars. Thus far, all Imperial Cruisers have been shown to utilize the same hull-type: a squat armored prow in front, capable of mounting a prow-mounted weapon system, and a big bunch of engines in the back, with baroque and Gothic architecture in-between. Most cruisers can effectively be placed in four categories:
- Basic: The Jack of All Trades cruiser. Carries both Broadside Lances and Macrobatteries.
- Lunar: The Lunar. You've heard so much about it and now you want to know what it makes it the standard Imperial Cruiser. First of all, it's one of the oldest designs still in use by the Imperium and is so easy to build that even less advanced worlds can produce them. They're quite versatile due to their weapons loadout (a balanced build of Macrobatteries, Lances and Torpedoes) and make up the backbone of Battlefleets throughout the entire Imperium. This is the cruiser against which all other cruisers are measured.
- Emasculator: Considered a failure by the Imperium at large, Emasculators have the same basic load-out as the Lunar, but are keel-built, lacking the armored prow and replacing the torpedo tubes with more weapons batteries. This means they require different tactics to a Lunar, using their speed and longer ranged weapons to pound ships from a distance. As this fits with Chaos tactics more than Imperials. most of them ended up as traitors. The name Emasculator is due to them being seen mostly as Slaaneshi ships, their original name is unknown.
- Slaughter: A special type of Cruiser, the Slaughter-class has a more powerful drive called the Scartix Engine Coil, but lacks prow weapons. Armed with short ranged, but powerful lances and macrobatteries, the Slaughter is designed to get in close, blast away and retreat. Unfortunately, the Imperium can't build them anymore because one went traitor and destroyed the plans for the Scartix Coil. It is unknown if they were always called the Slaughter-class or were renamed when most went traitor.
- Inferno: A earlier counterpart to the Carnage-class, carrying more lances in exchange for some Macrobatteries. Had the same difficulties as the Carnage and was mothballed, though a few went renegade beforehand.
- Lance-boat: Replaces Macrobatteries with more Lances. Rarer as they have a weakness to Void Shields and require better drives due to the power requirements of the lances.
- Gothic: Another variant of the Lunar Class, the Gothic is designed as a heavy Lance gunship. Due to the amount of Lance Weaponry it carries, it can easily deal with ships of its own size or larger but often does require an escort or a partner to strip enemy void shields first in order to use its own weaponry to the maximum effect. When supported and used correctly, Gothic Cruisers are the most efficient way to deal with enemy capital ships.
- Ordnance-boat: Opposite of the Lance-boat, replaces Lances with more Macrobatteries. Usually this is because they need extra power due to mounting a Nova Cannon or having power-hungry macrobatteries such as Plasma Cannons.
- Dominator: A variant of the Lunar Class, the Dominator is designed primarily for planetary bombardment and assault. Not generally used in fleet actions even though it can provide support with its Nova Cannon when necessary. After one Dominator fucked over a Chaos Cruiser with said Nova Cannon during the Gothic War, the Navy took note and started making more Dominators. Additionally, another Dominator came close to destroying the Terminus Est (aka the toughest Battleship in the galaxy), before being destroyed.
- Tyrant: The Tyrant was originally intended as a stand-off vessel; it would stay at long range and bombard enemies from afar with superfired plasma weaponry. Unfortunately, due to design compromises where it mixed both short range and long range weaponry to save on power, it wasn't really deadly enough at long range to do its job. Therefore the Imperial Navy is trying to replace the short range weapons with ancient Long-range weaponry (that doesn't use a lot of power) recovered from Space Hulks or Renegade Ships. The Hull itself is a rather effective design and so the Tyrant has become very popular with Rogue Traders who generally replace all of the Plasma Weaponry in order to have more power available compared with other cruisers.
- Relentless/Carnage: Another attempt at a fleet support ship with Plasma weapons, the Relentless ended up with technical difficulties and, when these were overcome, most ships ended up turning traitor (including the lead ship of the class). This is theorised to be due to something wrong with the geometry of the ship's design, as the Relentless-class is keel built, like most older ships (This also means the Relentless lacks an armored prow and torpedo tubes, carrying more plasma batteries instead). The tendency of these ships to turn to Chaos, along with changing tactics, led to the class being renamed the Carnage-class and mothballed in favor of the Tyrant-class, though their speed means they suit Chaos tactics famously.
- Carrier: The red-haired stepchild of the Navy. Replaces the Lances with Launch Bays and is disliked by most Admirals due to the stigma against Attack Craft. Chaos likes them more because they can fill the bays with Assault Boats. Some Carriers are also made from wrecked cruisers of other types, in which case damaged broadside weapons are ripped out and replaced by launch bays.
- Dictator: A Carrier retrofit of extremely damaged Lunar Class Cruisers. If a Lunar class has its lance weaponry destroyed, it's quicker, easier and cheaper to replace those with heavy launch bays for strike craft. This makes it quite versatile and able to deal with virtually all situations and interestingly enough, makes it more effective than the original Lunar Class at everything except fighting as a ship of the line. Unfortunately, the Lunar Class is designed for fighting as a ship of the line, so Admirals dislike Dictators.
- Jupiter: A kitbashed design, converted from other classes of cruiser that have been heavily damaged in battle. By stripping out all the damaged components and replacing them with launch bays, you get a pretty sturdy carrier. Just don't let the enemy get anywhere near it. Apparently the Imperium doesn't build these normally at all, likely because they are absolutely shit at defending themselves from other Cruisers.
- Devastation: Deviating from the standard Carrier design, the Devastation-class carries Lances instead of Macrobatteries. Mostly turned traitor or mothballed, as they lack armored prows and torpedos; and are keel-built. Chaos likes them, as they can pack them with mutants and sit back to spam assault boats and lances at anything that looks at them funny.
- Other: Various other cruiser types exist, but are rarer.
- Ambition: Custom-made Cruisers for the exceedingly affluent - it's the Rolls Royce of the Cruiser World. Most Rogue Trader ships are second-hand, battle-scarred, tired and worn ex-navy vessels but the Ambition is not. It's the only cruiser class that can be bought brand spanking new by Private parties in the Imperium and each one is unique and built to the customer's specifications. These exclusive ships, whilst still cruisers and deadly in their own right, are stately homes and status symbols. Some durability sacrifices have been made in order to make them the most opulent and luxurious ships on the market but for eccentric people like Rogue Traders, it's generally worth it.
- Conquest-Class Star Galleon: Built for the very first Rogue Traders on the orders of the Emperor himself, the Star Galleon is an ancient and noble design. Whilst not considered heavily armed by modern standards, they're still formidable opponents and yet as specialist exploration vessels they are able to operate independently for many years and can transport greater quantities than other Cruisers. In effect, it's a cruiser fused with a transport and looks fucking amazing.
- Murder: The predecessor to the Lunar. Differs by being keel-built, exchanging their torpedos for Lances and having more powerful macrobatteries. The majority that appear in modern 40k are Chaos-aligned, as the Imperials mothballed theirs in favor of the Lunar. A few carried lances as well as Macrobatteries, meaning they don't fit into any category. As with the Slaughter, it is unknown if Murder-class is their original name or they were renamed.
Smaller than true cruisers, light cruisers are used in two ways. Either you use a fast, maneuverable light cruiser like the Dauntless to add some extra firepower to a scouting squadron or long-range patrol, or you use a pocket cruiser like the Voss light cruisers to add some heavy firepower and armor to a convoy, fleet, or base. The advantage of the light cruisers are that they're cheaper to build and operate than real cruisers. Like the Cruiser, they fit into a few base categories.
- Basic: Same as its larger sibling, a Jack of All Trades.
- Dauntless; The standard Light Cruiser of the Imperium; it's a Jack-of-all-Trades. You can't go wrong with the Dauntless even though other Light Cruisers may be better for certain tasks. Considered 'scouting' cruisers, these make up the bulk of Imperial Patrol Squadron leaders.
- Defender: A convoy escort variant of the Dauntless, with added dorsal weaponry.
- Endeavour; A 'heavy', Light Cruiser, designed as a stop-gap between the 'lighter' light cruisers and true cruisers. Whilst they can slug it out in a fleet fight, they can easily be overwhelmed because they simply aren't cruisers and don't have the equivalent fire-power or hull integrity. As an added titbit, most of Battlefleet Koronus' patrols consist of an Endeavour and a pair of frigates.
- Lathe-class Monitor-Cruiser; An Adeptus Mechanicus Light Cruiser designed around deep space exploration and extreme self-reliance. These ships, when properly outfitted, can operate for decades without returning to imperial space for resupply. These would make up the bulk of Explorator fleets.
- Secutor-class Monitor-Cruiser; An Adeptus Mechanicus Light Cruiser designed to excel at the art of war. Tougher than all of the other Light Cruisers and yet still more mobile than true Cruisers. Due to being designed from the ground up to be a Warship, this Light Cruiser is fitted with Cruiser sized Void Shield Generators.
- Siluria; Three-quarters the cost of the Endeavor, and about three-quarters the ship. Standard weapon batteries only, no fancy frills to speak of. Cheap and effective, at short range, to catch enemy torpedoes.
- Lance-boat: Also the same as the Cruiser version, though some have weak weapons batteries for better defence.
- Endurance; Light Cruiser with just enough guns to claim it has them, lance batteries and a couple of torpedoes. It's the lance half of a Lunar, nothing more.
- Carrier: More useful as a Light Cruiser, as it can act as backup for patrols.
- Enforcer: A carrier variant of the Dauntless. Designed to maintain control of rebellious planets via intimidation (and possible orbital bombardment). Given one managed to stop the rebellion of an entire sub-sector, its a shame the Imperium doesn't build more of them.
- Defiant; A carrier variant of the Endeavour. It's quite versatile (by virtue of being a carrier) and so has found a home in many Rogue Trader houses but unfortunately the Imperial Navy doesn't consider it as useful because they can't stand by themselves and require an escort. Due to being based off of the Endeavour, it's relatively well armoured for a Light Cruiser and that does help with its survivability.
8 kilometer long battering rams. No, really. Tyranids and Orks are busy taking notes.
Ranging from about 1.4-2km long. They are used for all sorts of duties from convoy escorts to attack or patrol squadrons. Ironically named, as in real life Frigates were the same as Cruisers (which were not Ships of the Line).
- Basic: Laser batteries only, maybe some Torpedoes if you're lucky. Named after types of swords.
- Sword Frigate: The most common warship in the Imperial Navy, and one of the simplest. No torpedoes or lances to distract you here; a Sword puts two massive laser batteries behind a pointed armored prow and cuts into enemy formations like a multi-laser through canon.
- Falchion Frigate: A new (245 years old) class of escort ship built by Voss Prime. Slow as balls but still capable of firing torpedoes. While Cobras are used offensively in fleet actions, Falchion's are designed to be convoy escorts and stick close to larger warships to defend them from enemy escorts. Effectively a Voss-pattern Sword with torpedo tubes and one laser battery.
- Claymore Corvette: Designed entirely around escorting vulnerable transports and protecting them against light raiders in order to allow true Frigates to accompany more valuable ships such as Battleships, Battlecruisers and Cruisers. The Claymore Corvettes are easy to mass produce and maintain and are exceedingly common in the private sector, as they are simply a discount Sword.
- Gladius Rapid Strike Frigate: A modified version of the Sword-class, used by the Space Marines as an escort for their strike cruisers. Has 20% more powerful engines than a Sword, making it more mobile, which suits the Marines strategy perfectly. No prizes for guessing why it's called the Gladius.
- Turbulent Heavy Frigate: Heavy Naval Escorts; these things have comparable armour to cruisers. They're built to sally forth ahead of the main fleet and win skirmishes against enemy scouting forces and vanguard elements. They've garnered a reputation for being lucky; they've contributed to many glorious victories and survived catastrophes that other ship classes have not. Their only downside is that they have rather antiquated communication equipment, probably equipped for durability, not ease of use.
- Lance-boat: Rarer for Frigates, as they need a Prow slot to mount a Lance.
- Firestorm Frigate: A Sword-class frigate with a prow-mounted Lance replacing one laser battery. Gives the Sword some extra anti-ship punch that it dearly needs. For some reason it's two hundred metres longer than the sword and yet it's apparently only a refit, though the gun sticking out of the front likely is to blame for the extra length. The Navy does not like the Marines having them, for some reason.
- Thunderbolt Heavy Frigate: Not much information on this one, but implied to be a Lance version of the Turbulent, like how the Firestorm is the Lance version of the Sword.
- Given the general naming scheme for Frigate classes is naming them after weapons (Claymore, Sword, Falchion, Gladius etc), the Firestorm would make more sense being called the Lance-class due to its role.
- Nova Rapid Strike Frigate: A super-special version of the Firestorm for the Marines. As Lance armed ships are optimised for fighting other ships instead of attacking planets, the Navy considers the Nova to infringe on its turf and gets uppity when a Chapter has too many, thus they are uncommon.
- Brawler: Mostly upgunned Frigates. Can carry a mix of macrobatteries and small lances.
- Tempest Strike Frigate: Specialized Brawling frigate designed for devastating enemies at close range. Basically a Sword with a triple armoured prow and heavy short-range broadside batteries. They're often equipped with Assault Boats and Barracks for boarding actions.
The most common warship class. Their tasks range from scouting to shuttling VIPs or fighting in fleet engagements in large squadrons. Most pirates use these speedy, nimble vessels to prey upon transport ships.
- Basic: Usually mounts Prow Torpedos and a Macrobattery.
- Cobra Destroyer: The PT-Boats of the Imperial Navy. Small, fast, and lightly armed, their one purpose in life is to fire shoals of torpedoes from 3-8 ship squadrons. A great part of the Imperium's military advantage (in fluff and on the tabletop) comes from all the torpedoes they can fire at the enemy, and the Cobras are a big part of that.
- Hunter Destroyer: A Space Marine knockoff of the Cobra. Mostly used by the Dark Angels as
their mistrust of other factions means they can't acquire actual Cobras or ask the Navy for help.+++the Dark Angels simply do not want to bother the Navy with their hunt for traitors with no connection to the First Legion
- Havoc Destroyer: Small, yet fast raider sized vessels almost rivaling frigates in firepower. In large squadrons these can easily overwhelm larger vessels by weight of fire.
- Infidel Raider: Was meant to replace the Cobra, but the plans were stolen by Chaos. Armed with Prow Torpedos and a Macrobattery like its predecessor, though some Chaos fleets upgrade them to Heavy Raiders by adding another Macrobattery.
- Iconoclast Destroyer: If there ever was an Guardsman of starships, the Iconoclast is it. A destroyer so shitty the Navy doesn't want it, the Iconoclast mounts 1-2 macrobatteries and is used by Rogue Traders, Chaos and Pirates. Notable for being one of the few ships to have a forward placed bridge, likely due to the smoke-stack like pylons along its spine.
- Lance-boat: Rather rare among Raiders, as most use their Prow slots for Torpedos.
- Apostate Heavy Raider: A variant of the Infidel. Somehow those heretics managed to shove a full sized Lance into a Dorsal slot, which only Light Cruiser and bigger can normally manage.
- Idolator Raider: Also known as the "WTF is this" ship, the Idolator is the lovechild of a Infidel, a Firestorm and Xenotech. Has a prow lance and a macrobattery.
- Other: Mostly weak scouts.
- Viper Scout Sloop: Smallest warp-capable ship in mass production. It is an exceedingly fast scout ship with ridiculously powerful realspace engines and high-tech auspex scanners. In support of Naval Operations these vessels would burn into enemy territory at high speed, collect as much information as possible and then warp back to friendly territory. Unfortunately they are so specialized that they can't do much else apart from that.
- Rudense "Class": A small ship designed post Gathering Storm to be as fast, heavily armed, and densely armoured as possible, which they do with aplomb. You may ask yourselves, why are they not used in more regular combat roles? Well, the answer is that they are a specialised orbital insertion ship - designed to get as close to the atmosphere of a heavily defended planet as possible, drop it's cargo of primaris marines into the top layer, and get out of there. Whilst this may seem too specialised to be practical, few enemies are ready for half a company of marines dropping in to their base unexpectedly. (Nb - the class hasn't been formally named yet but the only example of it thus far was named the Rudense).
The fighter's main role is to stop enemy torpedoes and bombers before they can rip your flying cathedral multiple new assholes. Comes in different models like the Fury Interceptor or the Thunderbolt Fighter. The main difference is that some can enter a planet's atmosphere to dogfight and/or strafe ground targets where others are limited to space combat.
Basically reusable torpedoes. Come in different models like the Marauder Bomber and the Starhawk Bomber, but again the main difference is that some can dip in a planet's atmosphere and drop bombs on ground-pounders where others are space-combat only.
Armed Freighter (in the Battlefleet)
Ships bought, borrowed or stolen and then armed in the misguided attempt to boost the strength of a fleet in desperate need of ships (instead of simply using the legio cybernetica to make robots to do the monotonous manual labor so 90% of the hundred thousand crew members can be spread out amongst a hundred more warships)
A fancy name for a fuckheug bomb. A old, damaged or for whatever reason no longer usable ship is packed to the brim with explosives and flown straight into the heart of the enemy formation. Again, Orks are busy taking notes for their Roks.
Ships used for the transportation of cargo or individuals. The majority of Imperial ships would fall into this category.
- Carrack-Class Transport Ship; A newer version of the Conquest Star Galleon. It's a hardy vessel that can defend itself quite well against raiders. The profile even looks like a Military Vessel so opponents who can't distinguish between Imperial Ships could be scared off.
- Goliath-Class Factory Ship; An Adeptus Mechanicus vessel designed to harvest plasma from Stars. These ships supply the fuel for the entirety of the Imperium. Other ships can be fitted with Plasma Scoops to top up their own tanks but this is the true fuel-harvesting-workhorse of the Imperium.
- Jericho-Class Pilgrim Vessel: Refinery ships that have been converted into personnel carriers, the majority of which will be transporting poor-er passengers. Can't really defend itself but usually not even worth the bother for pirates.
- Loki-Class Q Ship; Converted Cargo ships designed to sacrifice some space for added weaponry. They can serve as Convoy defence in a pinch and can surprise the odd pirate who may underestimate them.
- Orion-Class Star Clipper; Blockade runners through and through. They're designed to transport low-volume but high-quality goods, even through hostile space. Speed is the name of their game. Hell, these things can put some Eldar ships to shame.
- Universe-Class Mass Conveyor; Think Super-Tanker in space. It's the largest standardized Cargo hauler in the Imperium and is 12km long. It looks freaking awesome too.
- Vagabond-Class Merchant Trader; Rather small cargo vessel but extremely common. As if to assist with its 'commoner' theme, it makes you yawn just looking at it.
Navy crews are made up of officers, techpriests, slave drivers, and slaves.
A bit of an over-simplification, but broadly true. Due to the Imperium's aversion to AI and Automation each ship needs at least thousands of people to man it. Whenever the crew count gets low, the Imperial Navy sets up fake strip clubs on a planet claiming "Free Hookers" to lure in unsuspecting men (and the occasional woman). Once a future crewman steps in, he's knocked out, bound, gagged, and taken to the ship, where they'll slave away the rest of their soon-to-be-short existence doing everything needed to make flying through space and fighting in the void possible.
This includes dragging shells the size of houses into cannons while being whipped. Still, at least for the crew sex is allowed, in fact encouraged, if for no other reason than maintaining the crew complement. Seriously, whole fucking cities and civilizations arise from the more massive ships, every bit as intricate as a long lived Hive City. Here is an idea of how it works, right up to the Roman armor, whips and beatings. Oh and apparently besides whole civilizations, there are whole civilizations of mutants around too. They can more or less settle new worlds for da Emprah by simply disgorging their excess population, which the crew is probably all too happy to do.
One area where fluff hasn't been consistent is in the uniform worn by Imperial Navy crewmen. Some sources suggest that uniforms are divided by segmentum of the Imperium, while others suggest that it is a sector-by-sector fashion choice. Given the scale the of the Imperium and the fact that Navy fleets are already identified by hull color, it's probably on a segmentum basis, but Games Workshop doesn't care enough to make a decision about it. For the ranks of the aforementioned shell draggers at the bottom of the naval hierarchy they'd wear a motley collection of their old civilian clothes and whatever they could scrounge up and sew together.
The ships of the Imperium travel through the Warp using what's called a warp drive to get to where they're going. However, this isn't your happy, fancy tunnel-of-light like in Star Wars, or everything-moves-fast Star Trek, it is an alternate dimension full of Chaos. In order to avoid being turned inside-out (think Event Horizon) and getting hentai-raped by every daemon in the warp, the ships rely on what is called the Gellar Field to keep the furries, undesirables, and various other evil beings out of their ship when traveling through. The Baroque decorations are also implied in helping to ward off said daemons. They rely on a Navigator that uses the Empra as a beacon to safely navigate the Warp, hence the title "Navigator".
While the Imperial Navy uses a lot of the ranks in similar fashion to modern militaries, they invariably hold to a more archaic form and are not equivalent to modern day ranking systems. Particularly since it's quite clear that commissions in 40k can often be purchased rather than earned, and that a "Warrant" would most likely hold to the original term and be an "officer by appointment" rather than an enlisted grade. Though considering the immense variety of units within the Imperium, this may not necessarily be the case galaxy-wide, so all options are equally valid.
- Lord-High Admiral of the Imperial Navy - This guy is a High Lord and is the single dude responsible for the ENTIRE Imperial Navy, though likely he doesn't do much other than delegate to his subordinates and attend tedious High Lord meetings.
- Lord-High Admiral - There are five of these guys, one for each Segmentum. While they're probably never anywhere near the front lines they probably have more to do, since its their job to oversee the deployment of fleets and materials from sector to sector.
- Lord Admiral - The guy in charge of a sector fleet who gets direct command of vessels and formations. You see these guys in the fluff quite regularly when "key" worlds (like Armageddon) need defended or attacked.
- Solar Admiral - Often a terminal rank... no really. Occasionally regular Admirals who do good jobs can put themselves forward for promotion to this position, which needs to be approved by the Lord-High Admiral, then the officer needs to travel to Terra be reviewed by the Lord-High Admiral of the Imperial Navy. Obviously this can take a very, VERY long time to approve. So they might often be dead before the promotion gets approved. If they get approved they are likely to get promoted straight up to sector commander (see Lord Admiral) as a position will have probably opened up while he was waiting. More rarely, Solar Admirals can get sent on "detached duties" which is basically a license to do as they please with their independent fleets.
- High Admiral - Commands several group of naval fleets (e.g. Battlegroups), often the most senior Navy officer in a Crusade but the things these fucks usually do is just having snacks with their Imperial Guard counterparts and leaving the combat duties to their subordinate Admirals
- Admiral - Gets put in charge of a fleet and told to oversee some subsectors. He's usually the highest of the "front line" ranks and much of his time will be on active duty patrolling his assigned region.
- Vice Admiral - Fleets traditionally get split into three parts, with the highest Admiral taking up the portion containing the larger ships, while the "Vice" Admiral takes the "Vanguard" portion of faster moving ships.
- Rear Admiral - the third portion of a fleet would be the "Rearguard" and usually gets assigned to the youngest/least experienced Admiral in the fleet. His job is usually the quietest one as he gets the mop-up and repair duties.
- Commodore - an experienced Captain in command of a squadron of capital ships. It's traditionally only a temporary rank, as capital ships don't always get assigned to each other the same way that escorts do. But the realities of war often mean that ships stay together for extended periods, often well beyond the lifespans of generations of captains.
- Lord Captain - not actually a rank, but an honourific applied to Captains of detached vessels operating independently. The "Lord-" part implies that they operate with the full authority of the the Imperial Navy when they act so they can deal with outside organisations (like planetary governors, Space Marines or Imperial Guard) on relatively even footing. Sometimes also known by the more archaic term of "Flag-Captain", since as the commander of a detached vessel they figuratively carry their own flag.
- Captain The commander of a single capital ship or the lead starship in an escort squadron.
- Commander - Usually the commander of an escort vessel. Is also the ranking officer on board orbital space stations. It also gets used as the terminal rank amongst Pilots, since small attack craft all fall under the remit of the Navy; so a Wing Commander would get command over all pilots based on a single carrier.
- Lord Lieutenant - The second-in-command to captains of capital ships, bizarrely Commanders don't hold that role and hold their own positions. Thankfully because a chain of command exists in any military, despite a Wing Commander holding higher "actual" rank over a Lieutenant on a carrier vessel he would not hold any higher authority on that ship than his duties allow for.
- Lieutenant - a "working" rank. Either holds command over small system vessels or acts as second in command to Commanders of escorts, or as department heads on Capital ships. They are also Squadron leaders amongst pilots.
- Sub-Lieutenant / Ensign - Team leaders or attack craft pilots
- Midshipman - Apprentice officers who haven't passed any exams or earned any responsibility, they would exist below the Warrant Officers in terms of authority, despite holding a commission. Midshipmen are commissioned from Imperial Nobility as part of the Imperial Tithe (which can mean virtually anyone gets the job if they send their useless heirs just to keep the best ones at home) but they are also assigned from the Schola Progenium. In addition, Midshipmen also may be taken on as a personal favour from the Captain of a vessel if he knows the family. This echoes the ancient real-world practice of young noblemen showing up while the vessel was in dock with a letter from their family and being granted a commission on the Captain's say-so.
- Ship Master - the most senior Warrant officer on board a starship, also quite possibly the busiest man on the starship. It's his job to maintain the logs, update stellar navigation charts, oversee ships stores and order supplies, and command a hangar deck if there is one. Basically he's the guy who knows the ship better than anyone. In real-world historical usage, this guy would have an authority equivalent to a Lieutenant on board a starship, and would "mess" (ie: occupy the same space) as the other officers do.
- Bosun - (Shorthand for Boatswain) The NCO directly responsible for all of the common crew members, including maintaining discipline. Despite his position, his actual rank may vary depending upon the size of vessel or operational requirements, in practice it never really matters since he's unlikely to ever meet another Boatswain. (real-world Boatswains could be proper Warrant Officers or not and held responsibility over all areas of the ship other than Engineering, which was left to the Chief Engineer, as if they disciplined/executed/imprisoned an skilled crewman from that department the ship could be crippled).
- Chief Warrant Officer - Also called "Chief Petty Officer" on some vessels. Will often be given command of important ship sections (like Chief Engineers, helmsmen, or auspex control, as these are are critical to ongoing operation of a starship)
- Warrant Officer - You'll find lots of guys of equivalent rank on a ship, in command of various operational sections keeping the ship running at all times:
- Masters of Ordnance - make certain that Torpedoes and Attack craft (if any) are fueled and maintained.
- Master Gunner - have responsibility over all of the weapons batteries and make ensure they are loaded and fired when required.
- Master-at-Arms - responsible for all "small" arms on board a starship, overseeing all Sergeants-at-Arms, as well as maintaining order over any barracked Guard regiments currently in transit.
- Master of the Vox - making sense out of the bazillions of messages that run through the bridge at any given moment both internally and externally (crews can get pretty massive, and a lot of traffic can come through at once).
- Steward - the guy who keeps everyone else well fed.
- Gun Captain - Funnily enough, the man in charge of a single gun crew. Makes sure that the weapon is taken care of, is reloaded quickly enough, and is accurate when asked to fire. All of that comes back to this guy.
- Sergeant-at-Arms - Man in charge of the weapons lockers and leader of boarding parties, as well as maintaining ship-board security. Usually they are transferred from Imperial Guard regiments so that they don't have any prior association with the crew.
- Armsmen - Crewmen trusted to carry weapons. They are not true soldiers as offensive boarding actions tend to be rare. So these guys still have their own regular responsibilities on board ship. Since they are trusted more, they have slightly more freedom to move around the vessel as well, though most Imperial employees really don't want the job, since it means they get scrutinised more, or they could end up beating up their buddies.
- Voidsmen - the lowest rank of crewman on board a Naval Starship above the Servitors unless the Captain is cool with slavery. If they have a skill or a trade they may be referred to as Able Voidsmen which is an official rank that might require examinations. Additionally, if they show leadership qualities they might be promoted to Leading Voidsman and put in charge of work gangs and be considered for promotion to Warrant Officer if a position opens up.
These are problems some have with the Imperial Navy and their fluff....
General Logistical Problems
The big problem that the Imperial Navy has is that it's the only organised navy in the galaxy that's trying to defend its massive amounts of space. To do this takes vast numbers of ships but rather thinly spread out. Given the problems of warp travel it's also extremely hard to reinforce friendly fleets under attack. The foes of the navy come essentially in two flavours; raiders who might just manage to scrape together a few converted transports (building even escort-sized ships is a huge undertaking, akin to building damn near the entire American Navy combined from iron ore and making it fly) which take an escort squadron to murder, and huge organized invasion fleets that take a whole fleet to fight. These combine together to mean that outside of fleet bases and important strategic worlds there is nowhere in the Imperium that is actually well-defended. At best a fleet has to be formed and sent out and they could arrive months later. Travel takes a lot of time, and out in the void it can be extremely hard to know what you are actually fighting against, especially since the enemy tend to kill anyone who tries to look at them. So when there's a large enemy force that you absolutely must fight (not fighting is much preferable) you don't just band together whoever was within shouting distance of the flagship and go murdering, you pull together every single vessel in the sector and hope to the Emperor it's enough to do the job.
Warships genuinely are vast things and obscenely expensive and risking them at all in major actions is not something anyone does lightly. Each cruiser is larger and more complex than a fully-kitted titan legion. These things are MASSIVE. In the BFG book there's a fluff story of a cruiser being built at a shipyard that orbits a primitive world. The entire population of the planet were given over to mining the resources needed to build one single cruiser. It took them eleven years to mine the ore. Sure, that's a primitive world, but if you think about it that makes carving out the rocks for it the largest single project ever engaged upon without mechanization. If you add together all seven wonders of the world you aren't even close to the pile of rock we're talking about. So these things are a big fucking investment and the high lords really don't like risking them without a really good reason (makes you questioning why they wouldn't build 20 smaller ships instead).
So if you ever wondered why the Navy doesn't get more action, now you know. By the time the big, awesome ships get on the scene the invasion already probably finished and the bad guys moved on. Then you nuke the shit out of them from orbit or drop millions of poor bastards into the meat grinder. Far better idea all round. It's the reason that the enemy, even nutters like Chaos, don't fight in the void without reason. On the ground it's just a scrap, and maybe you win or maybe you don't. If you lose in the void then your campaign on the surface is dead. No reinforcements, no support and a massive constant orbital bombardment to kill everyone left (which sometimes doesn't happen, because, you know, plot armour). That tends to mean fleets hover around and not fighting, one ensuring the other can't directly interfere with the surface war. This is actually an excellent and realistic explanation for why there is significant ground warfare in 40k. Also, ground-based defenses, mobile theater-shields, etc. are common. So, attacking a planet worth anything is like attacking a planet-sized Death Star without the super-weapon. Your ground forces taking out shields and anti-space batteries is critical to achieving anything. But, by that point, most of the enemy is dead and the survivors have either moved to the next defended region or got so stuck-in with your dudes that you can't shoot without killing your own army. Unless you worship Khorne, in which case you really couldn't care less who you kill, even yourself.
So, the navies of the galaxy ultimately get pushed down into either raiders, escorts against raiders, raider-hunters, or babysitting and logistical duty for groundpounders. Which of course brings back the question of why the Navy has such a desire to get more interceptors and bombers for ship-to-ship combat when they rarely engage in combat in the first place and the attack craft are insufficient. Could be to weaken the enemy ships' ability to shoot at the surface, but by the point they would have a target it would have (as stated) gone to a new defended location or whatever else, defeating the point of sending attack craft to weaken the enemy ships' offensive power. They won't shoot at each other, and they can't shoot at the surface (or at least can't shoot anything worth shooting at). In exchange for packing in so many attack craft into hangars designed for countless atmospheric air support fighters and bombers, the Imperial Guard has to die in radically greater numbers than they have any need to since they have limited anti-air capabilities and all of their enemies have no problem sending massive swarms of fighters and bombers at them. That is without even getting to engage the enemy on the ground and not counting the countless soldiers killed as the transports are shot to pieces due to their escorts commonly ditching them to go after obvious bait tactics.
Thus the rumor that the Navy has no balls. But who needs balls when you have a nova cannon sized dick and eighteen dice worth of fire power.
No one is quite sure how big the ships really are. One story claims the Retribution-Class is a mere 3 kilometers long, while another says it is 9 kilometers and up to 20 kilometers.
Your best bet is Rogue Trader, although going by those figures, anything bigger than a cruiser has an average density around that of hydrogen... From a helpful poster on Heresy-Online we have this:
For the most accurate scale, look towards the Battlefleet Koronus Expansion, as it is more a stat/rule book than a story. That and previous consensi, as well as cross referencing with the Horus Heresy rulebooks by Forge World (which places Battleships at 8-12km) place Cruisers just above 5 kms, and Battleships in the mid 8s. Please note that most ships above the size of 8ish kilometers are either a unique modified/purpose built flagship or a ship of a small class that is not in widespread calculations. For a sense of scale the largest warship in the world is currently the US Navy's Ford Class Aircraft Carrier measuring in at 337 meters long or 0.337km making the USS Ford the size of a cannon. They have guns literally the length of an Aircraft carrier!
- Transports and other Attack Craft, typically rated for atmospheric operation; also includes ships designed to be boarding torpedoes.
- <1 kilometer. That's the small ones, there are super transports in 40k as well. (A thunderhawk would go here).
- Escorts are "small" ships, like the Cobra, designed to flank foes and operate in squads.
- 1-2 kilometers.
- Heavy Frigates
- Light Cruiser, a smaller Cruiser.
- 3-5 kilometers.
- Cruiser, the standard fighting vessel; every Imperial fleet has them.
- 5-6 Kilometers.
- Battle Cruiser, a beefed up Cruiser; generally more 'modern' than a Grand Cruiser.
- 6-7 kilometers.
- Grand Cruiser; pocket-sized Battleship, very old.
- 7-8 kilometers.
- Battleship; the biggest of the lot, simply put.
- 8-12 kilometers.
- Fleet Carriers
The Horus Heresy novel "Know No Fear" had this to say about ship sizes, taken from /tg/ who quoted it from the book and written here is just the lengths and names of the ships, for simplicity and space:
- Macragge’s Honour. Twenty-six kilometers - Flagship
- Spirit of Konor. Seventeen kilometers - Battleship
- Antrodamicus. Twelve kilometers - Grand Cruiser
- Antipathy. Nine kilometers - Cruiser (note that the book said it had "six thousand lives" on board, which would be an absurdly small crew for its size by 40k or even 21st century standards - Cruisers normally have 85-95 thousand crew in 40k, and that's for normal sized ones, not double length ones like this one. But this is a Horus Heresy ship, so perhaps it's automation was much better then a later 40k ship)
- Aegis of Occluda. Seven kilometers - Class unknown
- Gladius. Four kilometers - Escort
- Then there is the Abyss-class created by Lorgar that is said to match the Phalanx in size. He made three of them.
If the weapons can annihilate a continent, why can't it destroy a mere hive? Because different writers don't talk to each other that's why. Also shields maybe.
Alternate take: Sure these weapons can destroy continents, but generally speaking why would the Imperial Navy want to bombard a probably Imperial Hive? Another thing to consider is that while Imperial warships are capable of *BLAM*-ing a planet, it requires a lot of ships firing either specialized planet-killing ordnance or just bombarding round the clock. One virus bomb/Cyclonic torpedo/lance shot would do comparatively little damage. But it does make you think about how powerful those void shields must be.
Another take: Something to keep in mind is the different size of ships and thus cannon barrels. A Retribution-class battleship is a lot bigger than a Mars-class battlecruiser is a lot bigger than a Turbulent-class heavy frigate, just to name a few. Different ships have different weapons.
Another Alternate take : The heresy novels elaborate a little on little on the practicalities of Orbital bombardment as a battlefield weapon. Whilst it is occasionally used tactically and reserved as a strategic level weapon, it requires utterly pinpoint accuracy (targeting being off by a millimetre in orbit could result in a shot being kilometres off on the ground) which is only possible when orbit is completely uncontested. It's use during land battles is the VERY definition of Danger Close and often a dead giveaway to the enemy, as allied forces have to withdraw kilometres away before ordering a bombardment, letting an enemy force bunker down or get out the way. Ships are also very easy targets for anti-orbital weapons during bombardment and the effect of a starship hulk hitting a planet you're fighting for is not something to be risked.
Lack of Balls
It is well-known that most Imperial Navy Officers don't have em.
An Imperial Navy fleet is most effective when Inquisitors take it over. See Here.
Not to be outdone by the Imperial Guard (as well as to compensate for their aforementioned lack of balls), the Imperial Navy has begun collecting music to either be blared on loudspeakers when not in active use, or in the case of battleship command decks, played live by orchestra. the first four are taken from Battlefleet Gothic Armada.
- https://www.youtube.com/watch?v=6DhAAGZVAVo This one is by far the best.
- https://www.youtube.com/watch?v=0AlLNITLk8A - A piece dating back to the Armada Imperialis' of the Great Crusade, but is still played regularly.
- https://www.youtube.com/watch?v=5STVoaxz8-Y - This instrumental is rumored to date back to some epic naval battle during the later dark age of technology.
- https://www.youtube.com/watch?v=wJEgAFR9vDc - While not quite fitting for battleships and grand cruisers, this piece dates back to when humanity was just beginning to march upon the stars, and as such, is heard regularly in ships captained by sentimental officers.
- https://www.youtube.com/watch?v=zUrSQNSN6_c - This fitting instrumental is often played in bastion fleets whenever they are mustered to put down yet another temper tantrum.
- https://www.youtube.com/watch?v=PAw1KlZ8C-A - Battlefleet Gothic Imperial port theme.
- https://www.youtube.com/watch?v=SlcUwUwjLrs - This ancient piece, a popular mobilization theme for the Imperial Navy, was apparently created during a time in which humanity was at war with a xeno species known as "Cylons". No other records of this species can be found.
- https://www.youtube.com/watch?v=so10dKbhorI - Another piece from the same era that the Cylons existed, it was created to commemorate a successful assault on a planet known as New Caprica, what is now an imperial hive world.
- https://www.youtube.com/watch?v=HFEHCuSnun0 - This was commissioned by a very srs bzns admiral.
- https://www.youtube.com/watch?v=Gii4e-h3DBc - This was commissioned by a very srs bzns admiral from Praetoria.
- https://www.youtube.com/watch?v=H7qOJrT_lUg - One of the pieces Lord High Admiral Langsung ordered to be played during the Battle for Port Sanctus.
- https://www.youtube.com/watch?v=Vu_Lp51wyao - This dated back to the glory days of human stellar exploration, when the universe was less grimdark, but is still a favorite for exploratory fleets, or for trying to distract yourself from the fact that you're just one energy field away from a level 99 rapefest.
- https://www.youtube.com/watch?v=pPLXNmKvLBQ - One of many favorites of those captaining Ironclads.
- https://www.youtube.com/watch?v=9TXlJ5DMq5o - A favorite of Vostroyan admirals.
- https://www.youtube.com/watch?v=elK5iReyAMI - Played during ceremonial ship or fleet launches since the great crusade.
- https://www.youtube.com/watch?v=IR5N0-DqZoU - One of many pieces played when the fleets return victorious.
- https://www.youtube.com/watch?v=Vm3q6dCeP7M - An orchestral litany created to aid in battles against chaos ships.
- https://www.youtube.com/watch?v=tvriqdS3vsc - A common theme of blockade runners, more nimble imperial vessels, and rogue traders plundering xeno planets in the name of the God Emperor.
- https://www.youtube.com/watch?v=bbh6HT7lLx8 - Popular among fleets in Segmentum Pacificus.
- https://www.youtube.com/watch?v=2NDn6WtZBJY - Popular among fleets in Segmentum Pacificus led by admirals from oriental cultures.
- https://www.youtube.com/watch?v=KylMqxLzNGo - Music played whenever the Navy has to perform exterminatus.
- https://www.youtube.com/watch?v=dZcj56XXrPM - A personal favorite of an admiral from Armageddon.
- https://www.youtube.com/watch?v=w3iwvG2ZKuw - The christening and launch of a new ship, straight out of the docks.
- https://www.youtube.com/watch?v=A9mFPDRZIgE - Encountering a Tyranid Hive Fleet
- A Comprehensive List of Ships
- Battlefleet Gothic Additional Ships Compendium
- A big poster of fictional navies, with 40k in the center left