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CHAPTER XXXI.

ENGINEERING INSTRUCTIONS.

SECTION 1.--TRIALS OF MACHINERY, ETC.

Dock trials.

1601. (1) Whenever a ship is fitting out at a navy yard, and her machinery is reported by the senior engineer officer of the yard (art. 1705) to be complete and in proper order, the commandant shalì, as soon as practicable after the senior engineer officer of the ship reports for duty, direct the senior engineer officer of the yard, in conjunction with that officer, to make such trial of the machinery, with the ship secured to the dock, as will enable them to ascertain its exact condition.

(2) If, as a result of such trial, any deficiency or maladjustment is discovered by them, the commandant, on their report, shall have it supplied or remedied and another trial made until the condition of the machinery shall be reported as satisfactory.

(3) The senior engineer officer of the yard and the senior engineer officer of the ship shall then make a joint report to the commandant of the yard, to be forwarded to the Navy Department, that they have personally examined the machinery of the ship and tested it by working, and that it is in all respects complete according to its design and in proper order for a cruise.

(4) They shall state specifically in this report that they have personally examined the interior of the boilers, that the condition of the plates, tubes, and bracing is satisfactory, and that the boilers are tight and clean inside and out. The maximum steam pressure with which they can be worked shall also be stated.

(5) They shall personally examine the surface condenser and ascertain if the tubes and tube plates are in good condition and free from leakage, and shall state whether the cylinders and their valves are in satisfactory condition.

(6) They shall report whether the apparatus for extinguishing fires and for pumping out the bilge and boilers are satisfactory as to condition and quantity, and shall give particular attention to the feed and bilge pumps attached to the auxiliary as well as to the main engines.

(7) The report shall also state that the proper amount of spare pieces, tools, instruments, and stores are on board.

(8) The senior engineer officer of the sh shall put a copy of the joint report in his remark book. (Art. 671.)

1602. In order that officers in command afloat may be enabled to administer their commands intelligently, efficiently, and economically; that the condition of the motive machinery may be ascertained; that sufficient instruction may be given to the engine-room force to enable them to perform their duties in the most efficient manner, and that data may be obtained for the use of the Department when designing engines, steam trials of ships in commission,

Power trials.

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in addition to any contractor's or tactical trials, shall, from time to

timę, be made as hereinafter provided. Full-power

1603. (1) Trials of ships in commission shall be made under full power, with natural draft, twice a year at intervals of not less than four months nor more than eight months; these trials shall take place in smooth water and with the ship's bottom comparatively clean.

(2) These trials shall last from six to twelve hours, preferably as near the latter as possible, if the power can be maintained by the engineer force divided in two sections.

(3) During these trials the engines shall be worked so as to use all the steam made by the boilers, the pressure being maintained as near the designed working pressure as practicable and the speed regulated by linking up with the throttle wide open. The speed shall be gradually increased up to the highest attainable under the conditions imposed.

(4) For the purpose of familiarizing the engineer force with working the boilers and machinery under forced draft there shall be made monthly, if the ship is at sea, a run of from four to six hours under an air pressure of not more than three-fourths inch of water and using for the purpose only such boilers as are in use at the time the trial is ordered.

(5) When the men of the engineer force have had sufficient experience with the boilers and machinery of a vessel to enable them to work the boilers to advantage under forced draft, the twelve hours' trial provided for in paragraph 1 shall include a period of four hours under forced draft, with an air pressure not exceeding one inch of water, or the maximum designed air pressure if this latter is less than one inch. This limitation of air pressure shall not apply, however, to torpedo boats.

(6) The first trial shall take place as soon as practicable after a ship which has just been commissioned, or extensively repaired, is reported by the commandant of a navy yard ready in all respects for general service. This trial shall be witnessed and reported upon by the Board of Inspection and Survey. Advantage shall, if possible, be taken when making passages from port to port, at times favorable for such purposes, to conduct the other full-power trials required, and they shall begin as soon as practicable after leaving port.

(7) The engine and fire room watches shall be so arranged that each and every man will be on duty for a portion of the time whenever forced draft is used on these trials.

(8) Salt water shall not be fed into the boilers during any of these trials if it can be avoided. To this end the water in the boilers will be at the highest steaming level when a trial is commenced and the evaporators will be run to make up the extra feed required.

(9) Should the condition of the machinery or boilers be such, in the opinion of the captain and senior engineer officer, as to render a full-power trial inexpedient on account of a liability to disable either entirely, it may, with the approval of the senior officer present, be postponed until the circumstances can be reported to the Depart

ment and a reply received. Endurance 1604. (1) The captain shall, from the beginning of the cruise,

take every opportunity when steaming, to ascertain (a) the greatest distance that can be run per ton of coal in smooth water; (b) the

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trials.

Steam trials in

greatest distance that can be run per ton of coal under varying circumstances of wind and sea. When determined, these results shall be reported to the Navy Department.

(2) In conducting these trials, runs of not less than twenty-four hours shall be made.

(3) In general these trials shall be as follows: Runs will be made at decrements of two knots, as nearly as possible, from the speed at full power. When the most economical rate of speed in smooth water has been approximately determined, other runs may be made to determine it more carefully. The data from other runs shall be used to verify the computations. Having fixed upon the greatest distance that can be run per ton of coal in smooth water, with a comparatively clean bottom, trials to ascertain what modifications are necessary under varying circumstances of wind and sea, also with a moderately foul and very foul bottom, and with a light, medium, and deep draft, shall be made as opportunities occur. Trials with a single screw, in ships fitted with more than one, shall also be made, the helm angle necessary to keep the ship steady being noted and reported. In all these trials the boilers and other appurtenances shall be operated in the most economical manner possible in regard to the consumption of fuel.

1605. (1) The result of all steam trials shall be reported by the captain to the Navy Department, with all the attending circum- general. stances, the condition of the bottom so far as known, the average indicated horsepower developed by the main and by the auxiliary engines, the consumption of coal per hour, the distance run per ton of coal, the pounds of coal consumed per mile, and the speed of the ship with all corrections applied. The number of auxiliaries in use at the time shall be stated. The speed shall be determined by as many different methods as possible, which will be described. The captain shall state in his report on the first full-power trial whether or not the machinery is in a satisfactory condition; if not, all defects and deficiencies will be fully described.

(2) During all steam trials the following rules shall be observed in regard to procuring data to be forwarded with the report. If circumstances will permit, the main engines shall be indicated every half hour, and the auxiliary engine in operation every hour; the horsepower of auxiliary engines not fitted for indicators shall be estimated; half-hour observations of the data required by the steam log shall also be taken. Should circumstances not permit, the periods for noting these data may be doubled. Great efforts shall be made during all trials to keep the steam pressure, vacuum. number of revolutions, and all variables as uniform as possible.

(3) Great care must be observed in weighing or measuring the coal, and in seeing that the fires are in the same condition at the end of the trial as at the beginning. The kind and quality of coal shall be especially stated.

(4) No full-speed trial shall take place in less than sixteen fathoms of water; depth of water shall be reported.

(5) During all trials herein referred to the coal as it runs from the bunkers shall be used. It shall not be hand-picked. During all full-power trials any assistance necessary to provide sufficient fuel in the fire room shall be rendered by the deck force, the amount of such assistance being mentioned in the report of the trials.

(6) In making full-power trials the speed of the engines shall be gradually increased, working for a time at about three-quarters power.

SECTION 2.-CARE OF ENGINES AND BOILERS.

Main engines.

1606. (1) The cylinders, receivers, and steam jackets must be gradually and thoroughly heated by opening connections between the boilers and engines as soon as the fires are lighted and before steam of full pressure is admitted to them. The greatest care must be exercised that “water rams are guarded against by carefully draining all pipes while raising steam.

(2) Water must not be allowed to accumulate in the jackets or receivers, but care shall be taken that steam is not being blown through the traps.

(3) Every opportunity shall be used to ascertain the proper grades of expansion in each cylinder for different powers; the powers developed in each cylinder should be equal, or nearly so, and when the proper points are ascertained a careful record must be made in the senior engineer officer's remark book for reference when changes in speed or power are required.

(4) The indicators shall not be allowed to remain attached to the cylinder when not wanted for immediate use; and they shall be dried, cleaned, and lightly lubricated with cylinder oil before being put away.

(5) No tallow nor oil of vegetable or animal origin shall be used for the lubrication of cylinders and valves, but mineral oil only shall be employed.

(6) As little oil as possible shall be used for interior lubrication; this prohibition is intended to apply to every steam cylinder in the ship, for whatever purpose intended.

(7) Care must be taken that the oil used for lubricating the rods is not drawn into cylinders in which there may be a partial vacuum.

(8) The cylinders, piston rings, piston springs, followers, and fol. lower bolts shall be frequently examined and their condition noted in the steam log.

(9) All cocks and valves throughout the engineer department are to be moved at least once each week.

(10) When not under steam, the engines and main valves are to be moved every day, when possible, and all steam machinery jacked at frequent intervals, the fact being noted in the steam log.

(11) Zinc plates shall be suspended in the hot wells and condensers to prevent corrosive action. The condition of the zinc and of the interior surfaces shall be frequently examined and noted in the steam log:

(12) All holding-down bolts shall be examined at least once in three months, and care taken that the nuts of pillow-block bolts do not become set fast. The clutch couplings shall be moved and lubricated once a day when not under steam.

(13) The gratings over the engine-room hatches are not to be taken off, except in cases of necessity, and shall be replaced as soon as possible.

(14) The instruments fitted on board for telegraphing signals to and from the engineer departinent shall be carefully examined, oiled, and tried before getting under way.

(15) Mineral oil causes rubber valves to swell and overlap each other. All such valves must be examined periodically, turned and trimmed to their original size, if necessary. Their condition as well as that of the condensers, at each examination, shall be noted in the steam log, with all further information that may be considered

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