Sorry, the quote I posted implies that there are differences in the hulls and their effect on how the weapons work. There are also differences in engines and turret amount. The Ret has 1 less turret and 5cm more speed. Are we assuming they downgraded the engines?
Differences, yes. Voss ships have different prows, the Emperor and Ret have different prows. There are cosmetic differences in appearance too. Lances are far more complex and consume a whole lot more energy to fire out to 60cm It's not off base to think that some of the additional power that was shunted to the rets engines is used to power the added lances.
The problem with this, game mechanic wise, is you have a ships with the same firepower as the Apoc with an extra turret and no downside for shooting over 30cm for the same point cost as the Apoc.
what downside does the apoc have at this point in the course of a normal game? When it's closing and doesn't want to turn it gets a BM and when it's within 30cm it doesn't matter. If you are concerned about the battery strength, try this instead:
Victory: 360pts
Battleship:12 Speed:15 Turns:45* Shields:4 Turrets:5 Armor:5+/6+
Armament: Range/Speed Firepower/Strength Arc
Port Lance Battery 60cm 4 Left
Starboard Lance Battery 60cm 4 Right
Port Weapons Battery 60cm 6 Left
Starboard Weapons Battery 60cm 6 Right
Dorsal Weapons Battery 60cm 6 Left/Front/Right
Prow NC
All it does is knock it down 1d6 against most targets over 45cm and drops the dice by 3 in a best case scenario.