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 Buoy 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)