actually, chaos ARE NOT corrupted imperial ships.
(on the table top anyway)
THEY ARE TWO COMPLETELY DIFFERENT TYPES!!!
(unless hosting a recently defected one)
note: by "chaos" i mean the traitor legions.
these are generally more firepower, less torps n lances. n sometimes faster. (slaughter classes

)
officially, marines only have three catagories on ships:
battle barges, (massive things with hideous firepower, brutal boarding skills, etc etc etc)
strike cruisers (mini versions of battle barges)
and rapid strike vessels (the rest. aka cobras, firestorms and swords)
i would also love to see this too. and on a LARGE scale too... (fighters n bombers in their carriers - work around is make the fleets bigger)
i do not know however, if the system which fleet picking is normally used (on the table top) SHOULD be used:
its generally limitless escourts (tiny things like frigates n stuff)
a helping of cruisers
and then rare battleships (duh)
might make it a bit borin though, although far more strategic
<-- loves ships, loves warhammer 40k.
khorne awaits!