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26 eR 1 NUE HIGH SPEED GASOLINE LAUNCHES One of the interesting papers read at the recent meeting of the Society of Naval Architects & Marine Engineers in New York was Mr. Clinton H. Crane's paper upon "High Speed Gasoline Launches." It received a great deal of comment at the time and Mr. Crane was highly complimented upon the performance. The paper was as follows: "The application of internal combustion engines to the pro- pulsion of launches is by ne means a novelty, but great public attention 'has of late been attracted to the subject owing to the high speeds obtained by a certain number of small launches driven by engines of this type. "Tt might have been expected that the makers of marine gasoline engines would have developed a light engine from the heavy slow moving engine which has been on the market for years. However, the demand for a light weight motor has so far been met only by automobile makers, although marine engine builders are now beginning to take up the . matter. "The older makes of motors weighed from 80 to 200 lbs. per brake horse power, and in sizes up to 75 H. P. have proved extremely satisfactory in all sorts of working vessels. En- gines of this type manufactured by the Pennsylvania Iron Works (Globe motor), Standard Motor Construction Co., and other well known makes have run satisfactorily day in and day out with practically no attention or trouble. "The manufacturers of automobiles have been the first to realize the possibility of a light weight motor, and have been 'able to reduce the weight per horse power to between 8 and 20 lbs. per brake horse power in the best practice of today. To have divided: the weight per H. P. by ten is certainly a remarkable achievement. "The reduction of weight has been accomplished in three ways: "7, The elimination of unnecessary material. 2. 'The employment of higher grade material. "3. The use of higher piston speeds. "The higher piston speed has necessitated modifications of design in four particulars--mechanical balance, ignition, lubri- cation and cooling. All four of these difficulties have been met with entire success in the engines used by automobiles. The slight change of conditions from an automobile to a boat has given rise to unforeseen troubles with ignition and lubri- cation. The ignition troubles have been principally due to water affecting the insulation of the electrical gear for igniting the gases; and this, by care in installation, can be readily corrected. "The troubles with lubrication arise from the fact that in a boat the engine driving the screw is ordinarily set at an incline, the result being that the after cylinders and bearings receive too much oil, the forward too little. It may not be generally known that in a gas engine too much oil is as bad as too little. Several systems of forced lubrication have been designed to meet this trouble, with more or less success, but the adjustment of the oil supply is of such delicacy that I think it safe to say that most people can trace their troubles in high speed motors to this alone. During the past year we have designed a dozen launches to be driven with light weight automobile engines of various makes, and the only troubles experienced have been with one or the other of these diffi- culties. "The extremely light weight per H. P. of the modern gaso- line engines has presented the possibility of attaining high- er speeds on the water than heretofore. The past year, though not yet having realized this possibility in point of ac- tual speed, has brought us to a point in relative speed never before attained to my knowledge. I present to the society as a type of this high speed automobile launch the Vingt-et-un "66 ge £ Vo tt fw IL., designed by my firm. This boat on public performance has shown a speed of over 22 knots per hour. "To attain, for her length, a speed relative to this Turbinia would have had to make 35.5 knots an hour instead of 32.76, as is credited her by report. To attain for their length a speed relative to this, torpedo boats would have had to make 44 knots an hour instead of 30 knots as actually obtained. From the fact that Vingt-et-un has attained such a high point on the speed curve I feel that the record of a progressive trial run last September on this launch over a measured mile would be of interest to the society. '""Vingt-et-un's principal dimensions are as follows: HULL, "LOW L328. ft. 0. in; beam, 4 ft, 7 in.) draught:ot hull, mean, If in.; wetted surface on trial including struts, rud- der, shafting, etc., 146.3 sq. ft.; displacement on trial, 3,850 lbs. ENGINES. : "Smith & Mabley Simplex four cylinders; diameter cylinders, 6%4 in.; stroke, 634 in.; revolutions, full speed, 850; piston speed, 956; brake horse power full speed, 68. TRIAL TRIP 'OBSERVATIONS. Time over measured Average Run. statute mile. revol't'ns 1 (ONGAINSE Ide! oo es, MIDS: Li SECS ee rae ee 380 VET EDO EIAS eerie ae oa eee Acmins. 4D.2-0 SECS... 6... 380 9 Against tide ice. ete, wr © Minsi 7) 2DiSECS. 5,5 cae 438 ; Waithibidier se cence ae 4 mins. 848-5 secs............ 425 3 Against idence SmMiis; SMSCCS Ao. to oe 670 1 With tide.... Peart QMS -491SECS. ee oe 690 4 ) Against TIM Oe ye Ce SINS AESeCSis 2 Va. Rae 740 WeWHTDeTIG ee ae Le Watch stopped by accident... 745 5 § Against tide................... QeNTITIS SS SECS: Leese Lo, 850 We Wathitidie 33 is Q-MINS seOvSECS. 265.2 as es 835 6 IORI IG aa et ora} gre tne Pease es e ) With tide...... ee Sie EB MMMM Se SOCS i os Serhan oes 56 JRun spoiled by drittwood met-) ee is a. he er ers a d ie CINGF ON StEMI et Se ole ee aC ten tetas es Veta aire, 8 WON Cans ttle... cert acer, AAS IESEG tat eee a 564 FWithitide 2. ees Simms. SOSeCS eg Ss 597 "Tn selecting a course to run this trial, owing to the small size of the boat, absolutely smooth water was a necessity. This was especially true with a gasoline motor, as even a small amount of spray on the electrical apparatus for ignition is sufficient to impair the regularity of the engines. It was not possible to count the revolutions without removing the for- ward part of the engine cover. We therefore chose a meas- ured mile course on the Harlem river laid out by the engi- neering department of the New York University, quite recog- nizing the disadvantages due to shallow water (an average of about 16 ft.) and a strong tide (a maximum of nearly two knots). One man was placed at the forward end of the engine with stop-watch and revolution counter to note revolu- tions, the helmsman taking the times over the course with and against the tide. The difficulties of observation were increased by the large amount of floating wood which had to be dodged. "Runs were made with and against the tide with engine speeds between 380 revolutions and 850. It was found im- possible to throttle the engine to a lower speed than 380 and have it run with sufficient regularity to make the result of any value. The engine had before installation been tested on the brake for a maximum power at varying revolutions. This brake horse power curve gave-us a value of 68 H. P. or 850 revolutions. 'The information which we principally desired to obtain was the rate of increase of power at the higher points of the curve not already investigated. The speeds were reduced from statute miles per hour to nautical miles per hour. The speed revolution curve was obtained by laying in all the spots with and against the tide, and figuring the tidal correction for each of runs separately on the assump- tion that for a small variation in revolutions the speed varied with the revolutions. "In constructing the effective thrust curve I made the fol-