. The observing party must be instructed to detectand promptly correct any errors in the recording of trialdata. It is important that the data be correct within thelimits of accuracy of the shipboard instructions.. The chief observer should instruct members ofthe observing party to report any violation of trialinstructions found in the NSTM or of sound engineeringpractice. The chief observer should verify any suchreport and then inform the commanding officer of theship being observed. He must also include in the trialreport a detailed account of any violation.Before beginning a full-power trial, engineeringpersonnel should hold inspections and test machineryand equipment to be sure no material item will interferewith the trial. The extent of the inspections and the testswill largely depend upon the recent performance of theship at high speeds, the material condition of the ship,and the time limits imposed by operationalcommitments. The type commander’s instructions willprovide requirements in most cases.Inspect and test reactors, boilers, main engines,pumps, auxiliary machinery, safety devices, pipingsystems, and all equipment necessary for the properoperation of the engineering plant. Make theinspections and test according to the PlannedMaintenance Subsystem (PMS), which prescribes testsand inspections for machinery and equipment. If thereare no PMS instructions, use the manufacturer’stechnical manuals. If you have no specific instructions,follow sound engineering practice.Not later than 1 day before a trial, the engineerofficer should report to the commanding officer thecondition of the main engineering plant. He should statethat the plant is fit to proceed with the trial, or that it isnot fit, and the reasons why. The trial must be postponedif the commanding officer believes that holding the trialmight damage or disable the engineering plant or causea personnel casualty.During the full-power trials, the following generalrules must be observed: (The rules also apply to othermachinery trials that may be held under the conditionsimposed.)l Gradually increase the speed of the engines to thespeed specified for the trial. Be sure to thoroughly warmup the machinery before beginning a full-power trial.Do this by operating at a high fractional power longenough to stabilize temperatures.l Operate the machinery economically and do notexceed designed pressures, temperatures, and speeds.. Do not conduct a high-speed trial in shallowwater. It causes excessive vibration and loss of speed,and it overloads the propulsion plant. The NSTM hasinformation on the proper depth of water for a specificship.• If it is desirable to continue a full-power trialbeyond the duration originally specified, continue theobservations until the trial is finished. Conduct the trialcontinuous without interruption. If a trial at constantrpm is discontinued for any reason, count itunsatisfactory and start a new trial. There can be nomajor changes of the plant set-up or arrangement duringeconomy trials.l During full-power or economy trials, record allnecessary data often enough to obtain a reasonablycorrect picture of the power developed and the fuel andwater consumed during the trial. You can compute theaverage power developed by diesel-electric plants fromthe kilowatt output of each propulsion generator set.Make observations at intervals not greater than one-halfhour, and make at least three observations regardless ofthe duration of the trial. In ships equipped with torsionmeters, make at least 10 torsion-meter observations athalf-hour intervals.The Deputy Chief of Naval Operations for FleetOperations and Readiness furnishes trial requirementsfor each ship to the commanders and units concerned.They cover engine speed for full power at variousdisplacements and injection temperatures.They also furnish the shaft rpm corresponding to15, 20, and 25 knots for the appropriate ships.Full-power trials for competitive purposes are 4hours long, as far as the report data are concerned.However, some restrictions may be placed on a giventrial because of fuel economy requirements. Check typeand fleet commanders instructions for the latestrequirements. The usual procedure is to operate the shipat full power until all readings are constant, and thenstart the official trial period. Economy trials are 6 hours,and each trial is conducted at a different speed.Trials once scheduled should be conducted unlessprevented by circumstances such as those in thefollowing list:. Weather that might damage the ship. Material trouble that stops the trial, or that mightcause damage to the machinery or personnel if the trialwere continued4-7
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