Board Thread:Warhammer 40k General Discussion/@comment-98.25.205.2-20130227024257/@comment-78.52.33.5-20140803004737

http://afterimagedan.blogspot.de/2012/03/bfg-ship-sizes.html

~ 7-8 kilometers long

though if you get some chapter that has old pre heresy ships, we can talk about twice as much (as battle barges are the SM verison of battleships) and we get data for 19-20km long battleships for example in "know no fear"

and chapter barques ( basiccally the floating fortress monastery) are probably bigger still

the crew is not as big tas that of the imperial navy, they are more based on servitors  though a crew of chapoter serfs will be on board... but be reminded, the most deadly cargo of a barge is the company or 2 of marines on board.

Consider them as rather spacious at least as far as marine compartments.. crew could be crmaped but  the marines do not really press gang crews of thousands of people together.. many things are automated