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34 "TAE MARINE. REVIEW ACCEPTANCE TRIAL OF THE PENNSYLVANIA The recent performance of the Cramr-built armored cruiser Pennsylvania during her final acceptance trial is worthy of careful study. The Pennsylvania is one of six cruisers, built or building at the Union Iron Works, Newport News Co. and Cramps, two at each yard. They are all sisters, identical in type and specifications. The final acceptance trial was conducted with the navy department's crew of engineers and firemen, and the. Pennsylvania is the only vessel of the American navy which has accomplished a trial of four hours with forced draft with the regular crew wherein the contract speed has been exceeded. - Prior to the Colorado and Penn- sylvania it was the custom of the navy department to conduct the final acceptance trials so that the boilers were run under maximum natural draft conditions for a set period. On these two cruisers a full forced draft four hours' trial was added and the success achieved was so marked that in the future such forced draft trials are apt to be required for all vessels. Such a policy would do much towards inspiring the entire service with the capabilities of the fleet. It also tests the drill and efficiency of the engineering force and refutes the old idea that naval vessels could never attain the speed that the contractors could under more advantageous conditions. The trial was conducted by the Board of Inspection and Survey, Capt. James H. Dayton, president; Capt. H. C. Leutz, Capt. Joseph J. Woodward, Com'dr Isaac S. Reeves and Com'dr Templin M. Potts, recorder. The contract for the six vessels of the Pennsylvania class called for the development of a speed of 22 knots an hour with an indicated horse power of 23,000. Under the former policy of the Bureau of Construction and Engineering certain lati- tude was allowed the builders in modification of design in order to enlist their heartiest cooperation. In the case of the Pennsylvania the results obtained ere directly attributable to certain modifications in the boiler room and engine room which resulted greatly in improving the speed and efficiency of the ship. The changes allowed by the government were the installation of a battery of thirty-two modified Niclausse boilers, the modifications being in the direction of larger tubes and drum and general simplification of details. The main steam pipe was increased from 13 in. to 15 in. diameter, because it was considered that for a piston speed of nearly 1,100 ft. a minute a pipe of the larger diameter would be a necessity. The boilers were built 'for 300 Ibs. and the arrangement of the cylinders was modified so as to eve a more direct fow to the steam: the order. in the department design being low. pressure, high pressure, intermediate and low pressure, which is changed in the Cramp design to high pressure, intermediate, low pressure and low pressure. Another radical change was that instead of the low pressure cylinders being assisted by introducing live steam from the boilers, this connection was dispensed with and instead the exhaust from the auxiliary was fed direct to the low pressure cylinders. It will thus be seen that the changes were thoroughly in touch with the latest marine practice involving high boiler pressure, ample steam pipe connections to convey an abundance of steam to the cylinders and a literal adherence to the principles of triple compound expansion by using live steam only in the high- pressure cylinders and allowing it to develop its full ex- pansive efficiency from throttle to condenser. A comparison of the trials of a sistership built at another yard becomes interesting. On her contractors' trial trip the average speed of this ship was 22.12 knots, with 25,750 H. P. on a coal consumption of 3.2 lbs. per indicated horse power per hour. The Pennsylvania on her contractors' trial trip last year averaged 22.43 knots, with an average indication of 27,750 H. P. on an average coal consumption of 2.2 per horse power per hour, the temperature in the uptake in the first case being over 1,000 degrees and in the case of the Pennsylvania 650 degrees. The Pennsylvania left Newport harbor about noon on Tues- day, July 25. At 2:40 p. m. her official forced draft trial lasting four hours was commenced under practically the same conditions as she maintained in the contractor's trial. The engine performance was highly creditable to the engine force of the ship, as the maximum indicated horse power of 30,150 was reached, the average for four hours being 29,843; aver- age speed 22.08 knots. Immediately after the completion of the four-hour forced draft test an eight-hour natural draft trial was commenced This lasted from 7 p. m. Tuesday The average results obtained were with all boilers in use. until 3 a. m. Wednesday. 19.8 speed and the average horse power 17,040. After the completion of the steam trials the baiteries as installed were tested and showed that the ship was perfectly strong in every respect and fit for immediate active service. The speed of 22.08 knots under forced draft was ascer- cnet e tained by plotting the number of revolutions 125.66 for four / hours on the speed curve constructed from the results of standardizing trials made at Provincetown a few weeks before. The draught of water on the trial course does not exceed 25 fathoms, which certainly is not enough for a vessel of the size and draught of the Pennsylvania. Had she been tried on the English deep water.courses she would have possibly increased he: speed one to one and a half knots. As it was the patent log showed an average of 228 knots. The Pennsylvania has not been docked since November which makes the per- formance all the more remarkable. This trial also was a triumph for the Niclausse boilers. At all times during the four hours' run there was an abundance of steam and the safety valves were blowing off. The coal used was run of the /mine "Cunmbertand instead of' Pocationtas ac used by the contractors in the official trials. By reason of the magnificent condition of the vessel in all depart- ments, too much praise cannot be given to the very effi- ' cient organization under command of Capt. T. C. McLean. Data in detail of the forced draft and of the natural draft trials is herewith given. Starboard. Port. Numbers of hours forced draft.. 4. Mean revolutions of engines.... PoA QR 126.37 Mean revolution of both en- PICS oy ek a ee 125.66 Steam 'pressure in boilers... .,. 283.75 Steam pressure in H. P. cylinder 250. Steam Pressure in Ist receiver BUCOLIte AEE a vas ee T2275 125. Steam pressure in 2nd receiver BPSD Oi oe BO-2h is a 40. Steam cut-off in H. P. cylinder.. OOo. an 80 Steam cut-off in L. P. cylinder.. 0 as ae Steam cut-off in L. P. cylinder.. Oo 7 Vacuums oe ee 2A B75 ae 24. Temperatures, fireroom:.... |... POS a 102.5 a injection. 3) yj. | Ga 73. " discharge 2. L322 es 129. . fecd water (0. [90.9.0 570; Revolutions of: air pumps per MOET ab ee aS eae Eley Sal. 20, Revolutions of circulating pumps Del PS id aes es Te 170. Grate Suriace i use. TOO, 3 Cos as loi. Po main éeneines%. © (eT 2he ee 14 480 85 Lowe Br both engines, <4 28,693 Mer i) E. Pu apxiliaties.,. 2 3S 1,149.85 7 a Hegrogeie I Ba 29,843.45 Pounds of coal per hour ' Per sq. ft. of grate in use 32,707 peril, Hi. P. main engines... pet Lo HOP smain engs. & auxs... Mean draft at beginning of trial F. 30' Toe A 25" >" (79 6c" oe ee ; : a