Military


Damage Control

Battle is the most severe test of a ship. Preparing a ship for battle begins long before the general alarm sounds. A thorough knowledge by all hands of the ship's systems and ongoing maintenance is integral to preparation for battle. This ensures that when pushed to the limit the systems perform to maximum capability. All personnel should strive for a complete knowledge of the ship's systems and the damage control procedures required to resist or control damage. This knowledge provides depth in the survivability organization by preparing personnel to assume the duties of seniors who may become casualties of the battle. Any weakness or failure to function at design capability is a weak link in the ship's ability to survive. Preparation for battle includes evaluating the survivability of the ship with systems degradations or nonfunctioning equipment. Pre-paration to exercise the options that survivability provides must be incorporated in training plans to ensure battle readiness. When the general alarm sounds, the ship must be materially prepared and the crew must be mentally and physically capable for battle. When preparations are thorough, the crew can go into action confident that they and the ship are prepared to survive the battle.

Survivability is defined as the capacity of a ship to absorb damage and maintain mission integrity. In this context, the goal of surface ship survivability is to enhance operational readiness warfighting sustainability for each surface unit by: Reducing the probability that surface ships will be detected; . Increasing the ability of those ships to withstand damage, and Improving the capabilities and skills of personnel to enable them to expeditiously handle recovery from combat scenarios or accidents and to promptly restore vital ship systems.

As was demonstrated during the Falkland Islands engagement, a hit from a single modern high-explosion weapon is capable of severely damaging a ship or rendering entire combat systems inoperable. Like-wise, potential losses from a chemical or biological attack could incapacitate more than one battle station. To address these and related threat scenarios, this publication has been updated to include the latest proven techniques and equipment that encompass all areas of ship survivability.

The Navy gives high priority to the identification of new technology applications through research and testing programs. Current efforts to improve ship survivability stem from lessons learned in the Middle East during Desert Shield and Desert Storm and from exercises conducted aboard the Navy's fire test ship, ex-USS SHADWELL. The test results and data support the introduction of modernized systems and equipment in both new construction and backfit.

Beginning with the design and construction of a ship, detection avoidance, damage absorption, containment of fire and flooding and recoverability are major survivability concerns. Ship systems contribute to isolation and redundancy so the ship can operate after damage. The combination of mission-essential systems and equipment, doctrine and operational procedures makes a ship survivable.

Just as the ship depends on all members of the crew doing their jobs, so too the ship's survival depends upon each system being in top condition of readiness operating as a functional whole. Survivability describes the equipment, its use, doctrine and procedures to contain, control and limit the effects of shock, contamination, nuclear detonation, fire, smoke and flooding. It also describes those systems that provide for maintenance of propulsion, electrical power,

PREPARING FOR DAMAGE

The basic tenet of good seamanship is forehandedness. In support of this, preparation for battle begins with the basic design of the ship. Testing throughout the design and construction phases is conducted to provide quality assurance and delivery of systems capable of damage absorption from all weapons effects. Preparation for survival in a battle situation is dependent upon maintenance of the ship's design capability and training of personnel. This training must focus on ship's systems and the procedures necessary to resist or control the spread of damage, continue to provide services to warfighting capabilities and to make essential repairs to support the ship's mission.

Whenever a ship goes to sea, the potential exists for damage from environmental elements, collision, stranding or from enemy action. The ship's design as an offensive weapons system includes an inherent capability to withstand the effects of our most frequent threat - that of heavy weather. Preparation for sea must include the expectation of heavy weather. This preparation will ensure the maximum degree of material readiness necessary to resist all potential damage

Ships in port are usually in a reduced condition of readiness, but must be prepared for heavy weather. When heavy weather is expected, preparations for getting underway may be made and the ship made ready for sea. If getting underway, the special sea detail must be set and all navigating, propulsion and ship maneuverability equipment made ready. If the ship is to remain in port, boats must be hoisted and secured or sent to a secured area. If boats cannot be secured, they must be moored in the lee of the ship by a single line. In addition, a watch must be set. Mooring lines on the ship must be doubled, additional lines run out, additional fenders rigged and anchor placed underfoot. All ship handling, mooring and navigational practices must be in compliance with good seamanship. Before the inport weather becomes untenable and when preparations have been completed, the ship should get underway.

SHIP CONSTRUCTION AND SUBDIVISION

The most important features of a ship's survivability are its subdivision design, to limit damage spread, and construction practices to ensure design integrity. The primary strength members of a ship are the keel and main deck regions that run the length of the ship. Its girders, frames and stringers connect and support the keel and main deck. A shell of steel plating supported by a web of longitudinal and transverse stiffeners serves to stiffen the structure. It is important to the strength of the structure that the members be unbroken. The structure of all ships must carry the loads imposed by the sea; warships must also be able to accept damage that can destroy a portion of the structure and its continuity.

To strengthen the stiffened shell, ships are divided horizontally by decks and vertically by bulkheads. Decks and bulkheads contribute to the overall strength of the ship and divide the hull into watertight compartments. In all ships the main deck, shell and their web of stiffeners, along with the decks and bulkheads, give the ship the strength it needs plus a margin that allows it to resist damage without failure. In addition to providing strength to the hull, decks and bulkheads divide the ship into compartments - tight spaces - so damage can be isolated and cannot spread.

Similar damage can have very dissimilar effects in varying parts of the ship. Flooding well forward or aft, with little loss of transverse stability, may cause the weather deck to submerge and the ship to be in danger of plunging. Flooding from the same type of damage located amidships may seriously impair stability and put the ship in danger of capsizing. The design of the ship is balanced to permit the ship to sustain damage over the same length regardless of location. The length through which the ship can be flooded and survive is known as the "floodable length." The floodable length is a design characteristic of the hull and is a factor in the placement of transverse watertight bulkheads.

The height to which the hull must be watertight is determined by calculating the effect of flooding, heel and roll. This results in a V-shaped determination in design extending from the top center of each transverse bulkhead to the skin of the ship on the waterline at the maximum design heel of the ship. Penetrations of the hull outside the V-line must be watertight. Within the V-line, nontight ventilation ducts with temporary closures for use during air tests are permitted in design and construction.

One of the most important of the subdividing features is the DC deck. Below the DC deck penetrations are limited to those that cannot be made at other locations. There are no fore and aft doors on combatants below the DC deck. Necessary penetrations are placed near the centerline where their effect will be minimal.

Compartment design and construction contribute to hull girder strength, the strength of the individual compartment and hence, the survivability of the ship. The tightness integrity of individual compartments contributes to the ability to isolate and localize the effects of damage.

Compartments have different degrees of tightness depending on their function and location in the ship. Oiltight spaces are built to prevent any leakage of petroleum products. Watertight spaces are built so there will be no leakage of water at a specified height or depth. Airtight spaces are built so that if air pressure is put into the space, the pressure will drop only a specified amount. This includes spaces within ship's collective protection zones, where installed. Fumetight spaces are built so that there are no visible or otherwise discernible openings. Nontight spaces do not retard the spread of CBR agents, fire or flooding.

Fire zones are a special class of subdivision. Fire zones are physical boundaries de-signed to retard the passage of flame and smoke and the spread of fire. Fire zone boundaries use transverse and longitudinal bulkheads of tank and well decks as primary barriers to the spread of fire. Fire zone boundaries continue from the main transverse bulkheads through the superstructure, stepped as necessary. Fire zone boundaries are specially protected with fire retarding insulation, insulating (intumescent) paint, gaskets and other material designed to retard the spread of flame and smoke. In new ships, ventilation systems do not cross the boundaries between fire zones. All fire zone boundaries are at least fumetight. All US Navy ships over 220 feet in length are divided into fire zones. The distance between fire zone boundaries is never more than 131 feet. Fire zones are indicated by the letters FZ on ships' general arrangement drawings.

Collective Protection System Zones are another special class of subdivision (in some cases, co-located with fire zones) with features that provide protection against the entry of CBR agents into protected citadels. Entry of airborne solid, liquid, or gaseous CBR agents into CPS zones is prevented by pressurizing the zone to approximately 2 inches of water above ambient pressure with specially designed and equipped filtration and ventilation systems. CPS zones are installed during ship construction at one of three levels, dependent upon the mission environment of the ship class. Level 1 provides for berthing, messing, and casualty-handling for 40 percent of the crew to support routine watch rotation in a threat environment. Level 2 provides Level 1 capability plus essential operating station CPS, such as bridge and combat systems spaces (i.e., CIC). Level 3 provides CPS throughout the ship. (Some engineering spaces are an exception in Level 3 ships.) Total protection is achieved in the CPS zone while there is limited protection in spaces such as engine rooms, which provide protection from everything except vapors. CPS zones are indicated by the letters PZ on ship's general arrangement drawings. The zones are airtight. Where watertightness is required, conditions for both watertightness and airtightness are met.



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