ENGINEMAN 1 & CThe trials that are considered to be routineship’s trials are numbers 3, 9, and 10 of the abovelist. Post repair, full power, and economy trialsare the only ones discussed in this chapter, butinformation on the other types of trials can befound in Naval Ships’ Technical Manual, chapter094.technicians carefully inspect it to determine thecause of unsatisfactory operation.Full Power and Economy TrialsPost Repair TrialThe post repair trial should be made wheneverthe machinery of a vessel has undergone exten-sive overhaul, repair, or alteration which mayaffect the power or capabilities of the ship or themachinery. A post repair trial is usually madewhen the ship has completed a routine navalshipyard overhaul period; the trial is OPTIONALwhenever machinery, has undergone only partialoverhaul or repair. The object of this trial is toascertain if the work has been satisfactorily com-pleted and efficiently performed, and if all partsof the machinery. are ready, for service.Trials are necessary to test engineeringreadiness for war. Except while authorized todisable or partially disable, ships are expected tobe able to conduct prescribed trials at any time.Ships normally should be allowed approximatelya 2-week period after tender overhaul, and a1-month period after shipyard overhaul, to per-mit final checks, tests, and adjustments ofmachinery before being called upon to conductcompetitive trials.Trials are also held from time to time to deter-mine machinery efficiency under service condi-tions, the extent, if any, of repairs necessary, thesufficiency of repairs, and the most economicalrate of performance under various conditions ofservice.The post repair trial should be held as soonas practicable after the repair work has been com-pleted, the preliminary dock trial made, and thepersons responsible for the work are satisfied thatthe machinery is in all respects ready for a fullpower trial. The conditions of the trial arelargely determined by the character of the workthat has been performed. The trial should be con-ducted in such manner as the commanding officerand commander of the shipyard may deemnecessary. In cases where repairs have been slightand the commanding officer is satisfied that theyare satisfactorily performed and can be testedwithout a full power trial, such trial may bedispensed with.INSPECTIONS AND TESTS PRIOR TOTRIALS.—The full power and the economytrials, as discussed in this chapter, are consideredin the nature of competitive trials. It is assumedthat the ship has been in full operational statusfor sufficient time to be in a good material con-dition and to have a well-trained crew.Any unsatisfactory, conditions found to bebeyond the capacity of the ship’s force should becorrected by the naval shipyard. When necessary,machinery should be opened up and carefullyinspected to determine the extent of any injury,defect, or maladjustment which may haveappeared during the post trial.Prior to the full power trial, inspections andtests of machinery and equipment should be madeto ensure that no material item will interfere withthe successful operation of the ship at full power.The extent of the inspections and the tests willlargely depend upon the recent performance ofthe ship at high speeds, the material condition ofthe ship, and the time limits imposed by opera-tional commitments.Not later than one day before a trial, theengineer officer must report to the commandingofficer the condition of the machinery, statingwhether or not it is in proper condition and fitto proceed with the trial.A certain number of naval shipyardpersonnel—technicians, inspectors, andrepairmen—accompany the ship on a post repairtrial. They check the operation of machinery thathas been overhauled by the yard. If a unit ofmachinery does not operate properly, the yardGENERAL RULES FOR TRIALS.—Duringall full power trials, and during other machinerytrials, the following general rules should beobserved:1. Prior to commencing a power trial, themachinery should be thoroughly warmed up; this2-50
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