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Tygre wrote:
Even in modern times not all shipyards can build warships. And not all naval shipyards can build the bigger ships. Some components would also take a long time to make.

Around WW2 gun barrels for main armament and armour plate were in short supply because of their lengthy construction times. Rolled homogenous armour was not adequate for warships, but thick face hardened armour of the right specification needed time to make.

indeed, i assume the Lunar class built on a feral world was built using imported components for some parts like the warp engines, plasma reactor, most of the weapons etc, with the planet below providing the raw hull materials and goods for trading to another world to buy the hard to make parts.


"long lead" and "needs specialist industry to make" items are a possible bottleneck for production, but in a war economy like the imperium, less so, in that their is the constant demand that would lead to higher production of these items, so thiers a reason for these specialist industries to be around at scale in the first place. They would put a limit on a shipyards ability to rapidly expand production, though. it doesnt matter if you can churn out 1000 lunar class cruiser hulls if you can only build 100 warp engines for them.

the fleet sizes in the BFG book as just as out of wack as the rest of the imperiums forces are in relation to its size. nothing is large enough, becuase a it would need to be so large as to make anything playable on the tabletop meaningless. its worth pointing out that the vast majority of the imperiums "space" is empty star systems with nothing of value, so it might be the case that their are many hundreds of light years of "wild space" between sectors of civilisation.

xerxeskingofking wrote:
its worth pointing out that the vast majority of the imperiums "space" is empty star systems with nothing of value, so it might be the case that their are many hundreds of light years of "wild space" between sectors of civilisation.

That is the case. Though the Imperium divides space up into sectors, in reality as admitted to within the BFG rulebook itself, the Imperium is really scattered oases of human civilization strung along warp routes and trade routes. Even within a sector, it is clusters of inhabited sub-sectors, with wilderness space in between. That is why there can still be numerous minor alien or non-Imperial human civilizations still to be discovered deep within space claimed by the Imperium.

It also may not be so easy to expand production of the rate limiting parts if the knowledge is jealously guarded by the Adeptus Mechanicus. The Tech Priests that know may keep to a small scale hand crafted or cottage scale industry for these rare components because they have more leverage and political power the rarer it is. The Adeptus Mechanicus is about hoarding information and high technology not disseminating it. What the Imperium gets from the Adeptus Mechanicus is the lower tech stuff while the Adeptus Mechanicus keeps the best stuff for itself.

I got some numbers off of Wikipedia and Lexicanum, plus professional experience, that might help put some of this into perspective.

I know we are talking about a Lunar Class Cruiser, but for the comparisons I am going to make, we are going to look at the Cobra Destroyer. Why? Simple fact is that it is the closest Imperial Navy ship size wise to actual real world Navy ships.

Lunar Class Cruiser
Dimensions: 5 km long, 0.8 km abeam at fins approx.
Mass: 28 megatonnes approx

Cobra Class Destroyer
Dimensions: 1.5 km long, 0.3 km abeam at fins (approx)
Mass: 5.7 megatonnes (approx)

Nimitz Class Aircraft Carrier
Dimensions: .332 km long, 0.076 km abeam
Mass: .1 megatonnes (approx)

Virginia Class Attack Submarine
Dimensions: .115 km long, .01 km abeam
Mass: .0079 megatonnes (aprox)

The smallest Imperial Navy Ship dwarfs the aircraft carrier, and the carrier dwarfs the sub. However, both a Nimitz and a Virginia take about 7 years to construct, even with these massive size differences. The Virginia is far more complex than the carrier, and has to squeeze a large amount of complex equipment into a very small amount of space. For comparisons sake, if we look at the Liberty Ships from WW2, they were initially constructed in aprox 230 days, while at the end of the WW2, one only took 42 days because of streamlined industrial base, more efficient manufacturing techniques, and improved worker skills. There was a single instance of one being built in 4 days and 15 hours, but that was a publicity stunt, and the ship required a lot of work pier side once "finished".

So what does this all mean? Higher tech components need more time, and welding/ structural work can be completed far more quickly than ships systems such as power, engines, reactor, weapons, sensors, plumbing, etc. Much like modern Nuclear powered ships, the reactor and other complex systems wouldn't be built on site, but built by specialists at other locations. Possibly starting well in advance of the actual hull construction in orbit.

11 years of primitive mining does seem like a stretch to supply all the metals needed for building a Lunar Cruiser, but without more information, it is hard to determine by how much. If it was an entire planets worth of people working towards this sole goal, and all they had to do was remove material from the ground and bring it to a starport/ mechanicus smelter, shear volume of workers might be enough. And since we don't know how long the ship was being built prior to the start of the mining, or how long it took after the 11 years, the exact nature of their contribution is fuzzy. Hot take is this was a publicity project for the local Governor, and the first place that ship went after leaving the planet was to a proper shipyard to get finished.

Being able to build a warship hull =/= Being able to build armaments.

If you've got a handful of lifters capable of making it into orbit, making the actual ship itself would be a breeze. That's the easy part. It's just a question of adding pressurised metal boxes onto each other. Shape is almost irrelevant in space (no air or water friction), so even the basic architectural elements are much simpler.

The question becomes whether or not you have the industry to make the engines, guns, control machinery, and torpedoes. You can simplify a gun (for example, by adding human loading instead of mechanised), but at the end of the day, someone still has to cast and prove the different pieces. That takes heavy industry of a considerably different magnitude to just making pressurised metal boxes.

And that's just today. I don't even know what sort specialised manufacturing apparatus would be needed to turn out a Gellar generator or a Nova Cannon.

tl;dr Building the ship isn't the hard part. It's the fitting out that will limit production rate.

In WW2 the US was eventually cranking out merchant ships at a rapid pace. But the Iowa class battleships were started before US entry in WW2 and were only completed in 1944. So weeks for transport and 4 years for a battleship. In wartime conditions when (outside of port harbour) your main facilities aren't being constantly attacked.

On the other hand HMS Dreadnought in peacetime was rapidly built, by pouring resources into it and stocking up on resources beforehand, in a year and a day.

The biggest drawbacks for the time were the guns and armour. In creating the special steel needed for these, not its assembly. It's why the HMS Vanguard used twin 15" gun turrets when it was designed for triple 16" gun turrets. There was a war on and reusing 15" gun barrels (already made) was quicker.

I can imagine the adamantium keel on an Imperial Battleship might take a while to create. Due to the strength needed and its sheer size.

For Tigre comment above: It really did not take that long to physically build the Iowa Class once you lay down the keel, though. Most of that time that you reference was more of the internal politics during WWII. You had two large factions in the US Navy back then. One wanted to project power through battleships, and one through aircraft carriers. For a while there, there was a lot of debate as to which way to go with the fleet. Ultimately the Battleships took a back seat as they were not considered to be the priority in ship construction. Once in the back seat all of the slots for large ships at the shipwrights went to the Carriers as priority.

Also, I believe that out of the eight, six battleships from the attack on Pearl Harbor were repaired,(some resurrected) and sent out to the fleet. Ironically it would have been cheaper and faster to build the Iowa Class instead, as a few took over a year and a half to get back to service and had to be sailed to Washington State for full repairs. There was a pride issue here. Once you have six of the old at sea, you don't need any new ones immediately, especially since these were not priority to the US Navy.

For the OP: IMHO you need four core things to make a lot of the varied capital ships that you see in the Imperial Navy. The capacity to build the ship, the knowledge and expertise to build the spaceship, funds, and access to any specialized material to build the ship. Lets take modern times as an example. Assuming that a country puts their minds to it, I would contend that many countries could make their own modern guided missile destroyers and cruisers assuming that they can afford it, have or get the shipbuilding expertise and capacity, and of course make it a national priority for them. Think of something along the line the Arleigh Burke Class Destoryers. Of course there will be a learning curve like all sea faring countries have, but I contend that it will smooth out given time and persistence. Now compare that kind of project to something like a nuclear submarine, where a submarine needs access to uranium as well as more advanced skills and expertise to build it. The list of countries that can do it gets shorter. Go to the next step of an aircraft carrier, and it gets more complicated due to carrier based aircraft is a whole expertise in of itself, and the list is only a handful of countries.

Translate that to the 40K world and many worlds can likely build escorts without too many problems. Getting to the cruiser classes is where it can be tricky in a reasonable time period, but likely for the easier patterns.(at least according to BFG) Getting more complicated designs and weapons may require the added expertise, cost, access to materials, or capacity to build the ship that many worlds does not have. Thereby the list of worlds that can build that particular type of spaceship is shorter, especially if the expertise/plans in question is suppressed by the authorities. Anything very specialized like Space Marine capital warships or IN Battleships, may only be allowed to or are only capable of being built officially at a very few locations.

With the rate at which everyone loses ships and gets them blown up, every civilization would need to complete warships once every 5 years in order to keep their numbers up.

 LumenPraebeo wrote:
With the rate at which everyone loses ships and gets them blown up, every civilization would need to complete warships once every 5 years in order to keep their numbers up.

Actually if one looks carefully at the sources, the overall frequency of capital ship losses isn't that high. It's just that stories tend to focus on pivotal apocalyptic battles where such ships are lost.

For example in the Gothic War, if one trawls the BFG sources carefully, the overall pattern is capital ships slugging it out and the loser usually disengaging after being crippled or otherwise coming out the loser, in order to get repaired and fight another day. They usually did not fight to the point of one ship exploding. Escort vessels did seem to pop like bubbles, though that may be an artifact of the BFG system, and some of those tabletop losses might have been recoverable after the battle.

Most of the time though pirates are going to be outmatched by a cruiser and will flee. A lone Chaos champion with a cruiser and a few escorts (which is a more likely scenario than Abaddon's Gothic War with whole fleets of Chaos ships) is unlikely to risk total destruction of their main asset that gives them interstellar mobility and so will likely stick to raiding and one sided battles against Imperial escorts and more lightly defended installations rather than try to engage in a fight to the death with an Imperial cruiser or battleship.

Imperial sector fleets are also more likely to be spread out to protect the various commerce lanes to keep vital supplies flowing, rather than be all concentrated in one fleet for a massive direct fleet battle. That means the kind of concentration of firepower that results in rapid destruction of capital ships is not that common.

Iracundus wrote:

 LumenPraebeo wrote:
With the rate at which everyone loses ships and gets them blown up, every civilization would need to complete warships once every 5 years in order to keep their numbers up.

Actually if one looks carefully at the sources, the overall frequency of capital ship losses isn't that high. It's just that stories tend to focus on pivotal apocalyptic battles where such ships are lost.

For example in the Gothic War, if one trawls the BFG sources carefully, the overall pattern is capital ships slugging it out and the loser usually disengaging after being crippled or otherwise coming out the loser, in order to get repaired and fight another day. They usually did not fight to the point of one ship exploding. Escort vessels did seem to pop like bubbles, though that may be an artifact of the BFG system, and some of those tabletop losses might have been recoverable after the battle.

Most of the time though pirates are going to be outmatched by a cruiser and will flee. A lone Chaos champion with a cruiser and a few escorts (which is a more likely scenario than Abaddon's Gothic War with whole fleets of Chaos ships) is unlikely to risk total destruction of their main asset that gives them interstellar mobility and so will likely stick to raiding and one sided battles against Imperial escorts and more lightly defended installations rather than try to engage in a fight to the death with an Imperial cruiser or battleship.

Imperial sector fleets are also more likely to be spread out to protect the various commerce lanes to keep vital supplies flowing, rather than be all concentrated in one fleet for a massive direct fleet battle. That means the kind of concentration of firepower that results in rapid destruction of capital ships is not that common.

In support of this, there is some of the BFG descriptions that allude to some of the out of action capital vessels were taken as prizes, or found as derelicts, and either refurbished or stripped down to something usable. In the rules of BFG a drifting hulk, most common outcome when a capital ship is out of action, is obviously considered to be victory points but alluded to them as prizes for campaign purposes. I believe that Orks and Chaos fleets are using prizes some way more likely refurbished capital ships. While more likely Imperial prizes are sent to the breakers to be stripped down to something usable, I think that a few of the Battlebarges and Battleships are said to be refurbished.

its worth pointing out that majority of the Chaos fleets were designed during the Great Crusade or Heresy, and a large number of hulls were originally built back then, and many ships of these now "traitor" classes were in imperial service for millennia until tech decay made them useable.

Depending on the level of corruption, it would be very likely that a chaos cruiser hull could be used either as parts for a exist "mothballed due to parts" ship of the same type in imperial reserves, or even brought back into service directly. they are 100% of value to the Imperium.

but yhea, cruiser losses are not the norm, with heavy damage followed by disengagement being more normal, which is partly why ships form the 30th millennium are still in service ("ship of theseus " philosophical Issues aside)

Deleted post. I hit the wrong button. Sorry Guys.