. The observing party must be instructed to detect
and promptly correct any errors in the recording of trial
data. It is important that the data be correct within the
limits of accuracy of the shipboard instructions.
. The chief observer should instruct members of
the observing party to report any violation of trial
instructions found in the NSTM or of sound engineering
practice. The chief observer should verify any such
report and then inform the commanding officer of the
ship being observed. He must also include in the trial
report a detailed account of any violation.
Before beginning a full-power trial, engineering
personnel should hold inspections and test machinery
and equipment to be sure no material item will interfere
with the trial. The extent of the inspections and the tests
will largely depend upon the recent performance of the
ship at high speeds, the material condition of the ship,
and the time limits imposed by operational
commitments. The type commander’s instructions will
provide requirements in most cases.
Inspect and test reactors, boilers, main engines,
pumps, auxiliary machinery, safety devices, piping
systems, and all equipment necessary for the proper
operation of the engineering plant. Make the
inspections and test according to the Planned
Maintenance Subsystem (PMS), which prescribes tests
and inspections for machinery and equipment. If there
are no PMS instructions, use the manufacturer’s
technical manuals. If you have no specific instructions,
follow sound engineering practice.
Not later than 1 day before a trial, the engineer
officer should report to the commanding officer the
condition of the main engineering plant. He should state
that the plant is fit to proceed with the trial, or that it is
not fit, and the reasons why. The trial must be postponed
if the commanding officer believes that holding the trial
might damage or disable the engineering plant or cause
a personnel casualty.
During the full-power trials, the following general
rules must be observed: (The rules also apply to other
machinery trials that may be held under the conditions
imposed.)
l Gradually increase the speed of the engines to the
speed specified for the trial. Be sure to thoroughly warm
up the machinery before beginning a full-power trial.
Do this by operating at a high fractional power long
enough to stabilize temperatures.
l Operate the machinery economically and do not
exceed designed pressures, temperatures, and speeds.
. Do not conduct a high-speed trial in shallow
water. It causes excessive vibration and loss of speed,
and it overloads the propulsion plant. The NSTM has
information on the proper depth of water for a specific
ship.
• If it is desirable to continue a full-power trial
beyond the duration originally specified, continue the
observations until the trial is finished. Conduct the trial
continuous without interruption. If a trial at constant
rpm is discontinued for any reason, count it
unsatisfactory and start a new trial. There can be no
major changes of the plant set-up or arrangement during
economy trials.
l During full-power or economy trials, record all
necessary data often enough to obtain a reasonably
correct picture of the power developed and the fuel and
water consumed during the trial. You can compute the
average power developed by diesel-electric plants from
the kilowatt output of each propulsion generator set.
Make observations at intervals not greater than one-half
hour, and make at least three observations regardless of
the duration of the trial. In ships equipped with torsion
meters, make at least 10 torsion-meter observations at
half-hour intervals.
The Deputy Chief of Naval Operations for Fleet
Operations and Readiness furnishes trial requirements
for each ship to the commanders and units concerned.
They cover engine speed for full power at various
displacements and injection temperatures.
They also furnish the shaft rpm corresponding to
15, 20, and 25 knots for the appropriate ships.
Full-power trials for competitive purposes are 4
hours long, as far as the report data are concerned.
However, some restrictions may be placed on a given
trial because of fuel economy requirements. Check type
and fleet commanders instructions for the latest
requirements. The usual procedure is to operate the ship
at full power until all readings are constant, and then
start the official trial period. Economy trials are 6 hours,
and each trial is conducted at a different speed.
Trials once scheduled should be conducted unless
prevented by circumstances such as those in the
following list:
. Weather that might damage the ship
. Material trouble that stops the trial, or that might
cause damage to the machinery or personnel if the trial
were continued
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