Here's a try at a classification system I just whipped up, its a total off-the-top draft, so attack it all you like.
CLASSIFICATION SYSTEM
NOTE
Passive Defensive Systesms: Armor Plating of various sorts, Ionic Shieldings, Redundancies, Anti-Fighter Batteries, a PDS, or ECM, Shockwave, or Carronade.
Passive Aggressive Systems: EWS, LRS, TD&R, Overthrusters, Stealth Generator, Stutterdrive, Shockwave, or Carronade.
Active Systems: Fighter Bay, Drones, Mines, Marines, Sunbursts, Decoys.
Battleship: (BB)
• 3 Batteries
• 6 Banks
• 15 Hull
• At least two passive defensive systems, at least two passive aggressive systems.
Battlecruiser (CA)
• 3 Batteries
• 4 Banks
• 14 Hull
• At least one passive defensive system, one passive aggressive system, and one active system.
Cruiser (CB)
• 3 Batteries
• 4 Banks
• 12 Hull
• At least two subsystems.
• No less than 4 Engines.
Light Cruiser (CL)
• 2 Batteries
• 3 Banks
• 9 Hull
• At least two subsystems.
• No less than 5 Engines.
Destroyer (DD)
• 2 Batteries
• 2 Banks
• 7 Hull
• At least one aggressive or active subsystem.
• No less than 6 Engines.
Frigate or Sloop (FF)
• 1 Battery
• 2 Banks
• 5 Hull
• At least one defensive or passive system.
• No less than 6 Engines.
Cutter or Attack Ship (LC)
• 1 Battery
• 1 Bank
• 2 Hull
• At least one aggressive, non-active system.
• No less than 7 Engines.