The USS Charon has 13 primary decks and three decks within the sensor pod, however, those decks are normally not inhabited.
Full Deck Listing
Deck A: Sensor Pod Level 3; Dorsal Sensor Array
Deck B: Sensor Pod Level 2; Forward Probe Launchers (p/s), Aft Probe Launcher, Probe / Communication Bouy magazine, Lateral Sensors
Deck C: Sensor Pod Level 1; Sensor Maintenance, Sensor Control Station, Probe Launchers Control Station
Deck 1: Main Bridge, Captain's Ready Room, Briefing Room
Deck 2: Crew Quarters, Crew Lounges, Forward Observation Lounge
Deck 3: Crew Quarters, VIP/Guest Quarters, Crew Mess, Science Labs
Deck 4: Crew Quarters, Cargo Bays 1-2, Impulse Engines (p/s)
Deck 5: Crew Quarters, Cargo Bays 3-4, Impulse Engines (p/s)
Deck 6: Crew Quarters, Recreation Room, Library, Holodecks 1 & 2 , Cargo Bays 5-6
Deck 7: Main Sickbay, Counselor's Office, Children's Center, Upper Engineering, Shuttlebay Observation Deck
Deck 8: Shuttlebay, Main Engineering, Crew Quarters, Science Labs, Stellar Cartography
Deck 9: Crew Quarters, Shuttle Storage, Security Offices, Ship's Brig, Interrogation Room
Deck 10: Crew Quarters, Cargo Bays 7-8, Main Deflector Control, Aft Torpedo Launcher
Deck 11: Deuterium Tanks, Antimatter generator, Aft Torpedo Magazine
Deck 12: Deuterium Tanks, Antimatter Storage Pods, Forward Torpedo Magazine
Deck 13: Phaser Array, Warp Core Ejection, Forward Torpedo Launchers (x2)