Here's something I've been wondering about for a long time. All of the fluff about Imperial starships indicates that even small ships have crews that number in the thousands, or even tens of thousands. My question is, what do all these people actually do? Obviously a lot of them are people like the officer cadre to command and maintain discipline, armsmen for security, tech-priests, and people to operate ships systems like gun batteries, but what about the common deck hands? The people who are press-ganged and such? The only thing I can think that they actually do is keep the ship clean.

I would read Relentless and the Rogue trader novels from small slave armies loading the cannons or turning gears. I would say there are as many roles or jobs on a space ship as there is in a capital city.

Pipe cleaner, air filtration scrubber, uniform mender, dish pig, food preparation menial, roster planner, mould scraper, ghilliam culler, fungi vat-farm tender, pressure guage monitor class 1 though 13, servitor polisher, munitions measurer, supply clerk class 1 through 44... do I need to go on? and that's just the legitimate crew - what about the black market? the supporting civilian population?

If you ever get a chance to read a Patrick O'Brien novel pay close attention to all the jobs of the crew - then multiple that by 100 or even 1,000!

We Will Use Manual Labour In The Future. This ain't Star Wars or Star Trek. Those big, house-sized guns have to be loaded and aimed by hand. It takes work crews of dozens with cranes and pulleys to lift a shell from the ready rack and sway it into a macrocannon breach.

For example: the short story Cross The Stars gives us a gun crew of 60-80 for 1 Mars-pattern macrocannon aboard a Lunar-class cruiser (for one shift, technically). It also tells us that there are 40 such guns per deck (and an unknown number of gun decks) on each side of the ship. Even if we assume only one shift of gunners, and only one gundeck, that still gives us a crew of 2400-3200 for one weapons component. For a Lunar, multiply that (potentially) by 5, and that gives you crew numbers of over 10k, just for the gunners...

And, of course, the various support roles mentioned by Giaus Novus Khan (I heartily second the advice on Patrick O'Brien's Aubrey-Maturin novels, btw), plus the Enginarium crew, Scutarii operators, Auspex readers, point-defence gunners, helm crew, stewards, pursers, galley staff, Ship's Surgeon, sick berth attendants, armsmen and other security personnel, vox operators, astropath(s), astropath's support staff, Navigator(s) and support staff, the officers and comand staff, etc.

Giaus Novus Khan said:

Who are not, by ancient custom, permitted to polish their guage glasses. That's the job of the Guage Polishers' Guild. Demarcation mate.

Don't forget: "Corpse Starch Facility Manager, operator, Gatherer and PR Flunkie

Also good to remember that on top of the millitary and engeneering jobs, you've still got to run was is essentialy a small, self contained city. That means fire, medical, finacial, entertainment, etc.

Alasseo said:

Actually, I think it was realized in an earlier discussion on the topic that, even if doing things by hand is very 40k:ish, it's not something you need to fall back on to explain why there is so much crew. By comparison, a modern aircraft carrier has a crew of some 3000 for the ship itself, and an additional 2000 dudes for serving the aircraft aboard when it's fully loaded for combat. That's 5000 dudes on a ship "only" 300 metres long and less than 100 metres wide at its widest point.

Scale up that size, and add extra people to account for the fact that the ship is a whole self-contained society where you could plausibly find any facility or service you could find in a town with such a population, and suddenly 30000 people on a frigate doesn't sound so implausible anymore.

By actually counting the volume of a ship (approximating it as a paralellepiped) and dividing by the crew, it turns out that even if the crew sounds like a lot, the final density of crew per volume isn't that big. I've arrived at numbers like one crewman per 5000 cubic metres.

In support, just directly scaling up from an aircraft carrior to an Imperial Cruiser using the beam length as a ratio, you arive at aproximately 84,000 crew. Not far off the 90,0000 given in the book.

Quicksilver said:

Except you should be scaling the crew with the total volume, not the length.