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.
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