Has anyone else noticed that the ship sizes in RT seem to deviate strongly from canon? I do not mean the bigger ships, which seem to be quite like they were in Battlefleet Gothic and other earlier material, but the smaller ships that seem to have bloated suddenly.

In BFG ship sizes conform pretty much to this fan-made chart:

However, if you look at RT books the smaller (Destroyer, Frigate and Light Cruiser classes) have double or even triple the lenght. I think it is pretty strange that while BFG and other sources point towards a wide variety of all sizes of ships from smaller 600 meter destroyers to huge 8 kilometer battleships in RT the variety of different ship sizes is much, much smaller with smallest being around 1,4 km and largest around 6 km.

Disagreement about the scale of ships in 40k is common, particularly over the Cobra. While there was eventually a common ground reached on the various BFG forums and fansites, GW themselves have never stated the dimensions of basically any of their ships. On the basis of authority, FFG canon wins out over fanon.

Errant said:

I would be tended to agree on FFG being more "canon" except for the little fact that they completely messed up by putting "mass" to the ships. According to FFG dimensions and masses the ships would be basically made out of gaseous hydrogen (the lightest known element in the universe).

As for the Cobra I kind of understand that its size raises questions especially when Codex: Space Marines gives its crew as 5 marines and 150 serfs and RT says its closer to 20 000 crew. However, according to BFG all Space Marine ships are basically fully automated with just a handfull of "actual " crew and everything else done by automated servitors.

As Errant said FFG is the first one to ever really nail down specifics on ships. Almost everything else is highly contradictory material from novels and speculation based on a few know factors such as the size of torpedoes. The ship mass thing is only a major issue with the larger ships, smaller ship masses are not too bad (maybe kinda sorta). But yes I did some math using iron and a grand cruiser... it was bad.. really bad. at which point I started to wonder if the air inside the ship massed more than the ship itself... never did the math though and just decided not to think about it to much.

Much of it can be traced back to the frigate centric build of RT the game. It is fairly obvious that components and their specifics are created by the developers to fit in the frame work of a "escort/frigate" class ship. The larger ships are obviously given stats so that they do not completely overshadow the smaller ships.

That having been said I do not see anything wrong with the given sizes as they jive fairly well and are mostly middle of the road as far as the fan estimates go. If you want outliers even in FFG there are examples of smaller ships, the smallest I remember is the 100meter mechanicus one from... lure of the expanse (IIRC).

I remember FFG replying to the weights, explaining that it was due to radically new metals that are in the future, and the use of artificial gravity dampeners and the like.

MILLANDSON said:

The problem is that while it would make sense to count gravitational dampeners which effectively "neutralize" part of objects inertial mass into the mass of an object fitted with them the masses in RT book are still too small. If the gravitational dampeners would be big enough to reduce the inertial mass to the pitiful amounts in the RT book, then the drives the ships use would be powerfull enough to stop and turn even the biggest cruisers literally on a dime. The sad fact is that FFG totally dropped the ball with them and thats all there is to it. Ignoring the "Mass" is simply the best course of action.

If you change Kilometers to Miles, that chart is suddenly FFG accurate.

Spook said:

Wait a sec... So you are saying that if I substitute the "Km" with "Mi" in that fanmade table it then corresponds 1:1 to FFG text?

If that is so then I'm beginning to thing that FFG actually did use the very same fanon table for sizes and just messed up converting kilomteres to miles and back again somewhere along the way

I just doubled the table numbers and it almost matched FFGs source. Everything else can be handwaved as unique snowflakes (except for mass). But ship lengths are always, always up to the GM/players. If they want an extended sword frigate and pay for a massive ramming spike, more power to them.

This chart is not based on mere fandomness. It has a ground in things Andy Chambers said/mentioned etc, not on record of GW though. heh

I prefer above sizes, though acknowledge FFG hs listed is what GW has said it is. Some / a lot ignore the FFG dimensions and stick with the older values.

There is a pdf online where Andy states that a lance turret is crewed by 250-500 people.

Account to a Gothic Cruiser for example and you'll see at max end 8 times 500 = 4000 crew for ALL gunnery aboard.

From that the 96000 crew FFG gives is extremely high.

It has also been mentioned that a hitpoint in BFG equals about 1500 crew members.

So that would give the Gothic 8 times 1500 = 12000 crewmembers.

Once I measured the FW tau ships. Used the real life dimensions of the Tau Manta and scaled it to the BFG launch bay and it is so weird but the dimensions I reached for the FW Tau vessels like that made them in perfect scale with the 3km long cruisers for the Imperial Navy the chart above gives!

Which leads to me the FW designer paid attention to the launch bay scale and the ship itself.

Gravitational dampeners wouldn't cut mass at all. They'd cut weight. Weight = Mass * Gravity (thank you secondary school Physics).

Thinking about crew for the ships, I once measured out the dimensions of a Lunar class cruiser for my players over a map of Manchester (wherein we dwell). Its bloody huge. Given that the ships don't occupy one plane (as does Manchester) and that in all the literature has ships teeming with huge numbers of faceless crewmen, 96,000 doesn't seem too big for a cruiser.

Compare to my favourite comparison, the real world Gerald R. Ford class Aircraft carrier, currently one of, if not THE biggest aircraft carriers afloat. at 333m long it is 15 times shorter than a Lunar class, it has a crew of 4,660.

If we scaled up solely on length, then a Lunar with similar crew requirements should have about 69,900 crew. Thats about 2/3 of the Lunars. Of course 15 times longer is not enough. The aircraft carrier is 77m abeam while our lunar class is 800m abeam. That over 10 times wider too.

Also from Imperial ship design compared to a carrier, Imperial ships are notably taller proportionally.

When you work out very crude comparisons of crew density an aircraft carrier weighs in at 0.181 crewmen per square metre. A lunar class weighs in at 0.0024 crew per square metre. And thats assuming both ships are on a single plane. As we've noted, Imperial ships are taller as well.

96,600 for a lunar class does not seem huge. It seems tiny.

I've been doing up a crude scale map of my player's ship (secutor light crusier). It's dimensions are 4.3 by 0.5 by 1.0km.

Some fun facts so far:

It has 8 (known) compartmentalized cargo holds (just 1 component). each holds 4 millions cubic meters and is as long as the aforementioned aircraft carrier, almost twice as high and twice as wide. which means, as a cargo, it could roughly carry 32 aircraft carriers (though how you'd get them out of the ship...)

The ship's 'palace' (luxury quarters, library, trophy room and observation dome) has more floor space than the Place of Versailles.

the crew quarters is 1.5 km long, 50m wide and 100m high. If I assume 8sq m floor space is need for each crew (the same size as an apartment I saw in new york) and standard ceiling heights, then it would fit 200,000 crew ( I only need 50,000). instead I assumed the extra space was taken up with public amenities and larger homes for the officers.

I'd love to see some numbers crunched for the Universe mass conveyor. I recon that at 12km long, you would be able to hold squadrons of frigates...

Agmar_Strick said:

Anyone remember when the Emperor BBV used to carry squadrons of Cobra DDs because they couldn't make Warp by themselves?

As for the crew quarters- 8m² per crewman is rather generous. The absolute minimum would be 6' x 14" (roughly 1.2m²), but I'd personally go with 8m² between 3. For trusted crew, that'd be in a separate compartment. For the average rating - Ordinary Voidsman (maybe even Able Voidsman), that'd be in a dorm with the rest of the watch/gang or as floorspace at their post.

Unnecessarily cramped, given the size of the ship? Yes. In keeping with the fluff we have for life aboard ship? Yes.