Chapter  2—ADMINISTRATION,  SUPERVISION,  AND  TRAINING can be accomplished by operating at a high frac- tional power. 2. The speed of the engines should be gradu- ally increased to the speed specified for the trial. 3.   The   machinery   should   be   operated economically,   and   designed   pressures, temperatures, and number of revolutions must not be  exceeded. 4.  The  full  power  trial  should  not  be  con- ducted in SHALLOW WATER, which is con- ducive  to  excessive  vibration,  loss  of  speed,  and overloading of the propulsion plant. 5.  A  full  power  trial  should  continue  beyond the length originally specified, and all observa- tions should be continued until the trial is finished. 6. The trial should be continuous and without interruption. If a trial at constant rpm must be discontinued  for  any  reason,  that  trial  should  be considered  unsatisfactory  and  a  new  start  made. 7. No major changes of the plant set-up or arrangement  should  be  made  during  economy trials. UNDERWAY REPORT DATA.—Reports of trials  include  all  the  attending  circumstances, especially  draft  forward,  draft  aft,  mean  draft, and corresponding displacement of the ship at the middle of the trial; the condition of the ship’s bot- tom; the last time drydocked; the consumption of fuel per hour; the average speed of the ship through the water; and the average revolutions of the propelling engines. The methods by which the   speed   was   determined   should   also   be described. Reports  should  also  include  tabulations  of gage and thermometer readings of the machinery in use, and the revolutions or strokes of pertinent auxiliaries. The auxiliaries in use during the trial should be stated. Each report should state whether the machinery is in a satisfactory condition. If the machinery’s  condition  is  found  to  be  unsatisfac- tory,  all  defects  and  deficiencies  should  be  fully described  and  recommendations  made  for  correct- ing  them. TRIAL  REQUIREMENTS.—Trial  require- ments for each ship cover the rpm for full power at   various   displacements   and   injection temperatures. They are furnished to commanders and units concerned, by the Chief of Naval Opera- tions  (Operations  Readiness  Division). As far as reports are concerned, full power trials are of 4 hours duration. The usual procedure is to operate the ship at full power for a suffi- cient  length  of  time  until  all  readings  are constant, and then start the official 4-hour trial period. Economy trials are of 6 hours duration, a different speed being run at each time a trial is  made. Once scheduled, trials should be run unless prevented by such circumstances as: 1.  Weather  conditions  which  might  cause damage to the ship. 2. Material troubles which force the ship to discontinue the trial. 3. Any situation where running or completing the trial would endanger human life. If  a  trial  performance  is  UNSATISFAC- TORY,  the  ship  concerned  will  normally  be required to hold a retrial of such character as the type commander may consider appropriate. The fact that a ship failed to make the required rpm for any hour during the trial, and the amount by which it failed, should be noted in the trial report. OBSERVATION OF TRIALS.—When full power  trials  are  scheduled,  observing  parties  are appointed  from  another  ship  whenever practicable. When a ship is scheduled to conduct a trial while proceeding independently between ports, or under the other conditions where it is considered impractical to provide observers from another ship, the ship under trial may be directed to appoint the observers. The  number  of  personnel  assigned  to  an observing party vary according to size and type of  ship.  The  duties  of  the  observing  party  are usually  as  follows: 1. The chief observers organize, instruct, and station the observing party. They check the ship’s draft, either at the beginning of the trial or before leaving port; supervise the performance of the engineroom observers; check the taking of counter readings; render all decisions in accordance with current directives; and check and sign the trial reports. 2-51