delivery ship by opening the compressed air valve to the fueling connection, or (2) have the supplying ship take a back suction, which also requires that the air valve be opened. As soon as the fuel hose has been cleared, IMMEDIATELY  uncouple the hose and return it to the delivery  ship. You also must be familiar with the procedures used to discharge fuel. The following list shows some of the steps typically used to discharge fuel oil: 1.  Be  sure  the  tanks  from  which  fuel  is  to  be discharged are filled and topped off to the 95 percent level. 2. If necessary, heat the oil to the temperature required  to  produce  a  viscosity  of  450  SSU.  This procedure  is  not  usually  required  with  distillate  fuel. 3. Sound all tanks that will be used. 4. Couple the fuel hose and rig it according to prescribed  procedures. 5. Line up the fuel oil system to discharge fuel, and test the operation of the fuel oil pumps. 6. Place red flags over the side of the ship at the fueling  stations. 7.  Be  sure  the  officer  of  the  deck  has  draft readings taken forward and aft before and after fueling. 8. Set the fueling detail, setup the fueling board, and fill in available data on the fueling sheet for the fueling  officer. 9.  Man  fueling  stations  about  one-half  hour before  the  expected  time  of  approach  of  the  ship  to  be fueled. Be sure personnel at the fueling stations test sound-powered phone circuits, connect air hoses to the fueling   connections,   screw   in   thermometers   and pressure gauges, warm up the fuel pumps, and open valves to the fuel tanks. When the fueling detail is ready and has made all required checks and preparations, report to the fueling officer. The fueling officer will inform the bridge and request that the smoking lamp be out. 10. When you get word to start discharging fuel, start the pumps and operate them slowly at first, then bring them up to full-rated capacity. Bui!d up a pressure of approximately 40 psi at the fueling connections. 11. Continue pumping at the rated pump capacity until a tank is down to approximately 35 percent of its capacity;  then  shift  pump  suction  to  another  tank.  Slow the pumps and stop them upon a request from the receiving  ship, 12. Remove fuel oil from the fuel hose by blowing air through it, or the delivery ship may take a back suction. Disconnect the hose and rig and handle them according  to  prescribed  procedures. 13. Sound the tanks and compute the amount of fuel  discharged. BALLASTING SYSTEM Whenever  a  liquid  is  shifted  from  one  place  to another aboard ship, there is an effect on the ship’s list, trim, or stability. One of your routine jobs is to reduce any instability. To do that, you should keep as many fuel oil tanks as possible filled with fuel oil to the 95 percent level. There may be other times when you may have to use the ballasting system to move seawater to or from empty tanks. Normally, you will need to do that only in case of damage or when the ship has an unusually small store of fuel oil that brings on instability. To keep the fuel oil tanks at 95 percent capacity, you should accumulate leftover fuel oil from partly used tanks so only those tanks actually in use are less than 95 percent full. This prevents free surface effect that occurs when a liquid only partly fills a tank and moves freely back and forth as the ship moves. There is some free surface effect when a tank is filled to the 95 percent level, but the effect is limited because the overhead interferes with the free movement of the liquid beyond a certain point. There is more danger of serious loss of stability from tanks that are half-full than from tanks that are 95 percent full. The ballasting system allows controlled flooding of certain designated tanks to control the ship’s stability. You can use the ballasting system to flood all tanks that are designated as fuel oil and ballast tanks and to flood certain voids. The ballasting and deballasting systems are arranged so all designated compartments and tanks can  be  ballasted  either  separately  or  together  and drained  either  separately  or  together.  Seawater  is  used as ballast, and it may be taken from the firemain or directly  from  sea  chests.  Use  drainage  pumps  or eductors  to  remove  the  ballast  water.  Handle  all ballasting  and  deballasting  according  to  the  sequence tables furnished for each ship or class of ship. Ballasting  empty  fuel  oil  tanks  helps  control stability by maintaining a low center of gravity in the ship and by keeping off-center tanks full to prevent off-center  flooding.  Ballasting  also  contributes  to torpedo protection—it provides a layer of nonflammable liquid at the shell of the ship to absorb fragments  and  otherwise  minimize  torpedo  damage. 6-10