The individual division officers are responsible
for maintaining the list in good physical condition.
The commanding officer, assisted by the
DCA, is responsible for filling in the column
marked Division Responsibility.
The divisions concerned are responsible for
securing fittings that are classified as XRAY or
YOKE. The ships repair parties are responsible
for securing ZEBRA fittings.
The term material condition of readiness refers
to the degree of access and system closure in
effect at any given time. The securing of access
fittings or systems limits the extent of damage that
could occur to a ship. To prevent interference with
normal operations, the ship does not maintain
maximum closure at all times.
For damage control purposes, naval ships have
three material conditions of readiness. Each
condition represents a different degree of tightness
and protection. The three material conditions of
readiness are called XRAY, YOKE, and ZEBRA.
These titles have no connection with the phonetic
alphabet. Furthermore, the titles are used in all
spoken and written communications that concern
Condition XRAY provides the least amount
of protection. It is set when the ship is in no
danger of attack. Examples are when the ship is
at anchor in a well-protected harbor or when
secured at a home base during regular working
Condition YOKE provides more protection
than condition XRAY. It is set and maintained
at sea during peacetime and in port during
wartime. It is also maintained in port during
peacetime outside of regular working hours.
Condition ZEBRA is set before a ship leaves
or enters port during wartime. It is also set
immediately, without further orders, when the
ship is manning general quarters stations. Also,
condition ZEBRA is set to isolate and control fires
and flooding when the ship is not at general
All watertight, airtight, firetight, and fume-
tight access fittings belong to a certain classifica-
tion of fittings. Although the fittings usually have
a basic classification, a select group of closures
within each of the three material conditions of
readiness are modified. The purpose of the
modified closures is to allow access to a space that
is secured because of the material condition that
is set. Once a material condition is set, no fitting
within the condition is to be opened without prior
authorization. Closures that are not modified
require permission of the commanding officer to
be opened. Permission to open a closure is
obtained through the damage control central
(DCC) watch or the officer of the deck (OOD)
when the ship is not manning the general quarters
stations. Repair party officers control the opening
and closing of all fittings in their assigned areas
when the ship is at general quarters. Any change
in the status of a fitting must be reported to DCC
so that the ships DC closure log maybe updated.
You may open a modified closure without any
special authorization. However, you are not
authorized to leave the closure open unattended.
Through careful attention to these procedures, a
ships watertight integrity can be maintained at
a safe level.
The following discussion will help you learn
about each classification, how the classification
is marked, what group of fittings have the
classification, and when you may or may not open
a fitting with that classification.
XRAY fittings are marked with a black X.
These closures are secured during conditions
XRAY, YOKE, and ZEBRA. You must not open
fittings with this classification without proper
authorization. You will find this classification on
the following access closures:
Doors and hatches to storerooms and
stowage spaces, including cargo ammuni-
Hatches that are provided with a scuttle
and lead to magazines and handling rooms
Bolted-plate manhole covers
Escape scuttles not covered elsewhere
Doors and hatches located only on the
weather deck and below that are used to
strike down stores and ammunition
Access to an aircraft fueling station
Access to escape trunks in machinery
Access to the arresting gear machinery
Access to the eductor room