Principles of naval engineering - Historic Naval Ships Association

Chapter 4- PREVENTIVE AND CORRECTIVE DAMAGE CONTROLknow how much water is coming in while wateris being pumped out.REPAIR OF STRUCTURAL DAMAGEFigure 4-5.— Tandem connections forsubmersible pumps.11.359type; it is driven by a water-cooled gasolineengine of special design. The pump delivers500 gallons per minute at 100 pounds per squareinch pressure, with a suction lift of 16 feet.The capacity may be increased by decreasingthe discharge pressure.The P-250 pump, which is similar to theP-500 pump except for capacity, is scheduledto replace the P-500 pump aboard ship. A P-250pump is shown in figure 4-6.In order to estimate the number of pumpsrequired to handle a flooding situation, it isnecessary to consider the amount and locationof the water to be removed, the capacity andavailability of the installed drainage systems,and the capacity of the available portable pumps.It is also necessary to know whether the leaksare completely plugged, partially plugged, ornot plugged at all— in short, it is necessary toThe kinds of damage that may have to berepaired while a ship is still in the battle areainclude holes above and below the waterline;cracks in steel plating; punctured, weakened,or distorted bulkheads; warped or sprung doorsand hatches; weakened or ruptured beams, supports,and other strength members; ruptured orweakened decks; ruptured or cracked piping;severed electrical cables; broken or distortedfoundations under machinery; broken or piercedmachinery units; and a wide variety of miscellaneouswreckage that may interfere with thefunctioning of the ship.One of the most important things to rememberin connection with the repair of structuraldamage is that a ship can sink just as easilyfrom a series of insignificant- looking smallholes as it can from one larger and moredramatic-looking hole. A natural enough tendency—andone which can lead to the sinkingof a ship— is to attack the large, obvious damagefirst and to overlook the smaller holes throughinterior bulkheads. Men sometimes waste hourstrying to patch large holes in already floodedcompartments, disregarding the smaller holesthrough which progressive flooding is graduallytaking place. In many situations, it would bebetter to concentrate on the smaller interiorholes; as a rule, the really large holes in theunderwater hull cannot be repaired anyway untilthe ship is drydocked.Holes in the hull at or just above the waterlineshould be given immediate attention. Althoughholes in this location may appear to berelatively harmless, they are actually extremelyhazardous. As the ship rolls or loses buoyancy,the holes become submerged and admit waterat a level that is dangerously high above theship's center of gravity.The methods and materials used to repairholes above the waterline are also used, forthe most part, for the repair of underwaterholes. The greatest difficulty encountered inrepairing underwater damage is usually theinaccessibility of the damage. If an inboardcompartment is flooded, opening doors orhatches to get to the damage would result infurther flooding of other compartments. In sucha case, it is usually necessary to send a manwearing a shallow-water diving apparatus down71