WATERTIGHT INTEGRITY

The watertight integrity of a naval ship is established when the ship is built. This original watertight integrity may be reduced or destroyed through enemy action, storm damage, collision, stranding, or negligence. The damage control officer (engineer officer) is responsible for ensuring that the ship's watertight integrity is not impaired through negligence. Any impairment that occurs must be corrected as soon as possible. The ship's material condition of readiness in effect

Figure 3-7.-Post-l949 compartment designations.

will also increase or decrease the ship's level of watertight integrity.

MATERIAL CONDITION OF READINESS

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 keep from interfering with the normal operation of the ship, maximum closure is not maintained 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 material conditions.

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 hours.

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 prior to leaving or entering port during wartime. It is also set immediately, without further orders, when manning general quarters stations. Also, condition ZEBRA is set to isolate and control fires and flooding when the ship is not at general quarters stations.

All watertight, airtight, firetight, and fumetight access fittings will be classified. Each classification applies to a certain group of fittings. Although the fittings are usually classified by a basic classification, a select group of closures within each of the three material conditions of readiness will be 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, except as noted. Closures that are not modified require permission of the commanding officer to be opened. Permission to open a closure is obtained

Table 3-l.-Compartment Letters for Ships Built after March 1949

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 ship's DC closure log may be 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 ship's 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 are not to open fittings with this classification without proper authorization. You will find this classification on the following access closures:

l Doors and hatches to storerooms and stowage spaces, including cargo ammunition spaces

s Hatches that are provided with a scuttle and lead to magazines and handling rooms

l Bolted-plate manhole covers

l Escape scuttles not covered elsewhere

l Doors and hatches located only on the weather deck and below that are used to strike down stores and ammunition

l Access to an aircraft fueling station compartment

l Access to escape trunks in machinery spaces

l Access to the arresting gear machinery room

l Access to the eductor room

l Access to the capstan and winch control room

l Access to the chain locker . Access to the stores elevator . Access to the catapult machinery room l Access to forced draft blower rooms . Access to fan rooms