Principles of naval engineering - Historic Naval Ships Association

Chapter 4- PREVENTIVE AND CORRECTIVE DAMAGE CONTROLof weight. In general, the most practicable wayof accomplishing this is to restore watertightboundaries and to reclaim compartments bypumping them out. Any corrective measurewhich removes weight from the ship contributesto the restoration of freeboard.Correcting for TrimThe methods used to correct for trim afterdamage include (1) pumping out flood water, (2)pumping liquids forward or aft, (3) counterfloodingthe high end, (4) jettisoning topsideweights from the low end, (5) shifting solidweights from the low end to the high end, and(6) pumping liquids over the side from intacttanks at the low end. The first of these methods—that is, pumping out flood water— is in mostcases the only truly effective means of correctinga severe trim.The correction of trim is usually secondaryto the correction of list, unless the trim is sogreat that there is danger of submerging theweather deck at the low end.Relieving Stress inLongitudinal Strength MembersWhen a ship is partially flooded, the longitudinalstrength members are subject to greatstress. In cases where damage has carriedaway or buckled the strength members amidships,the additional stress imposed by theweight of the flooding water may be enough tocause the ship to break up. The only effectiveway of relieving stress caused by flooding isto remove the water. Other measures, such asremoving or shifting weight, may be helpfulbut cannot be completely effective. In some instances,damaged longitudinals may be strengthenedby welding.IMMEDIATE LOCAL MEASURESImmediate local measures are those actionstaken by repair parties at the scene of the damage.In general, these measures include allon-scene efforts to investigate the damage, toreport to damage control central, and to accomplishthe following:1. Establish flooding boundaries by selectinga line of intact bulkheads and decks to whichthe flooding may be held and by rapidly plugging,patching, and shoring to make these boundarieswatertight and dependable.2. Control and extinguish fires.3. Establish secondary flooding boundariesby selecting a second line of bulkheads and decksto which the flooding may be held if the firstflooding boundaries fail.4. Advance flooding boundaries by movingin toward the scene of the damage, plugging,patching, shoring, and removing loose water.5. Isolate damage to machinery, piping,and electrical systems.6. Restore piping systems to service bythe use of patches, jumpers, clamps, couplings,etc.lighting.9. Rescue personnel and care for the wounded.7. Rig casualty power.8. Rig emergency communications and10. Remove wreckage and debris.11. Cover or barricade dangerous areas.12. Ventilate compartments which are filledwith smoke or toxic gases.13. Take measures to counteract the effectsof nuclear, biological, and chemical contaminationor weapons.Immediate local measures for the controlof damage are of vital importance. It is notnecessary for damage control central to decideon these measures; rather, they should be carriedout automatically and rapidly by repairparties. However, damage control central shouldbe continuously and accurately advised of theprogress made by each party so that the effortsof all repair parties may be coordinated to thebest advantage.PRACTICAL DAMAGE CONTROLBoth the immediate local measures and theoverall ship survival measures have, of course,the common aim of saving the ship and restoringit to service. The following subsections dealwith the practical methods used to achieve thisaim: controlling fires, controlling flooding, repairingstructural damage, and restoring vitalservices.It should be noted that controlling the effectsof nuclear, biological, and chemical warfareweapons or agents may in some situations takeprecedence over other damage control measures.Because of the complex nature of NBCdefense, this subject is treated separately in alater section of this chapter.65