128 AA BB CC DD
8 12 16 20
All frames forward of the forward perpendicular
the number 0; the others are numbered 01, 02, 03, as
applicable (fig. 3-6).
are identified by a capital letter, starting with A
(fig. 3-5). These frames are identified by starting with
the first frame forward of the forward perpendicular
and working forward. The frames aft of the aft
perpendicular are identified with double capital letters,
starting with AA. Starting with the first frame aft of the
aft perpendicular and working aft identifies these
frames. The frames between the forward perpendicular
and the aft perpendicular are identified by numbers.
The forward perpendicular is identified by the number
0 (zero). Each frame aft of the forward perpendicular
will carry the next higher consecutive number. The last
numbered frame is the aft perpendicular. If the forward
boundary of a compartment is located between frames,
the frame number farthest forward within the
Figure 3-6. Compartment designations.
compartment is used. Compartments located on the
ship's centerline carry the number 0.
The last part of the compartment number is the
Compartments completely to starboard are given
letter that identifies the primary usage of the
odd numbers, and those to port are given even
compartment. On dry- and liquid-cargo ships, a double
numbers. Where two or more compartments have the
letter is used to designate cargo spaces. The double
same deck and frame number, they have consecutively
letter will differentiate them from spaces containing
higher odd or even numbers, as applicable, numbering
the same commodity for use by the ship. Fuel oil and
from the centerline outboard. In this instance, the first
JP-5 jet fuel are two examples.
compartment to starboard is 1, the second is 3, and so
Compartment usage in the post-1949 system is
on. To port of the centerline they are numbered 2, 4,
shown in table 3-1.
and so forth. When the centerline passes through more
Access closures are numbered in the same manner
than one compartment, each of which has the same
as compartments, except that the letter designating the
frame number, the compartment having the forward
compartments use is omitted (example: 2-175-3).
bulkhead through which the centerline passes carries