U.S. Naval Ship Compartment Designations (Since 1949)

(Created October 2017)

Introduction to Naval Engineering, 2nd Edition by Blank, Bock & Richardson

In U.S. Naval ships constructed after March 1949; each space (except for minor spaces such as clothes lockers) is assigned a compartment number.

For example:





Deck #

Frame #

Centerline Relationship

Type of Compartment

Deck Number: The Main Deck is always 1. The first deck below the main deck is 2, while the second deck below is 3. The first deck above the main deck is 01, the second is 02.

Frame Number: The frame number at the foremost bulkhead of the enclosing boundary of a compartment is its frame location number. Where the forward boundary is between frames, the frame number of the forward frame is used. Fractional numbers are not used.

Centerline Relationship: Compartments located so that the centerline of the ship passes through them carry the number 0. Compartments located completely to starboard of the centerline are given odd numbers, and those completely to port of the centerline are given even numbers. When two or more compartments have the same deck and frame number and are entirely to port or entirely to starboard of the centerline, they have consecutively higher odd or even numbers, as the case may be, numbering from the centerline outboard. The first compartment outboard of the centerline to starboard is 1, the second 3, and so on. Similarly, the first compartment outboard of the centerline to port is 2, the second 4, and so on. When the centerline of the ship passes through more than one compartment, the compartment having that portion of the forward bulkhead through which the centerline of the ship passes carries the number 01, 02, 03, and so on, in any sequence found desirable. These numbers indicate the relation to the center-line, and are the third part of the compartment number.

Compartment Type: See table below.


Type of compartment



Stowage Spaces

Storerooms; issue rooms; refrigerated compartments.


Cargo Holds

Cargo holds and cargo refrigerated compartments.


Control centers for ship and fire-control operations (normally manned).

CIC room; plotting rooms, communication centers; radio, radar, and sonar operating spaces; pilot house.


Engineering control centers (normally manned).

Main propulsion spaces; boiler rooms; evaporator rooms; steering gear rooms; auxiliary machinery spaces; pumprooms; generator rooms; switchboard rooms; windlass rooms.


Oil stowage compartments (for use by ship).

Fuel-oil, diesel-oil, lubricating-oil, and fog-oil compartments.


Oil stowage compartments (cargo).

Compartments carrying various types of oil as cargo.


Gasoline stowage compartments (use by ship).

Gasoline tanks, cofferdams, trunks, and pumprooms.


Gasoline stowage compartments (cargo).

Gasoline compartments for carrying gasoline as cargo.


Chemicals and dangerous materials (other than oil and gasoline).

Chemicals, semisafe materials, and dangerous materials carried for ship's use or as cargo.


Living Spaces

Berthing and messing spaces; staterooms, washrooms, heads, brigs; sickbays, hospital spaces; and passageways.


Ammunition Spaces

Magazines; handling rooms; turrets; gun mounts; shell rooms; ready service rooms ; clipping rooms.


Miscellaneous spaces not covered by other letters.

Shops; offices; laundry;. galley; pantries; unmanned engineering, electrical, and electronic spaces.


Vertical Access Trunks

Escape trunks or tubes.


Void Compartments

Cofferdam compartments (other than gasoline); void wing compartments; wiring trunks.


Water Compartments

Drainage tanks; fresh water tanks; peak tanks; reserve feed tanks.