DISCUSSION ON MAY MEETING PAPERS. 47 



long periods, but for naval vessels considerably higher constants can be used with abso- 

 lute safety. 



Mr. Martin L. Katzenstein, Member (Commimicated) : — On page 8, Messrs. 

 Metten and Shaw, referring to the Diesel electric drive, enumerate disadvantages which 

 such a system suffers when compared with the direct drive. As regards the electric 

 equipment and its functioning, I shall enter no discussion, leaving that to the manufactur- 

 ers of that equipment, who are more familiar with the transmission and control of electric 

 current as applied to shipboard use, but concerning the Diesel engine running at moder- 

 ately high speeds, I believe that it is the opinion of many reputable engineers that the so- 

 lution of the problem of re-engining many of the present Shipping Board vessels will be 

 brought about by the use of the moderately high-speed Diesel engine transmitting its power 

 through electricity or some other means to the existing single-screw shaft. 



The disadvantages named by the authors, while applying possibly to engines run- 

 ning at such high speeds as would bring them near to submarine practice, are no doubt 

 justified, but when applied to moderate-speed engines will not hold in the face of current 

 experience. 



Taking up the objections as named, I should say that No. 1 as to loss in reliability in 

 prime movers is answered by the authors' reference to the motor ship Selandia, which, they 

 state, was put into service in February, 1912, and is still going strong. The auxiliary 

 engines on that vessel consisted of two four-cylinder 200 horse-power at 225 revolutions 

 per minute, and so far as I have been able to find, they are still running. The William 

 Penn, I believe, is fitted with auxiliaries of 100 horse-power, operating at 320 revolutions 

 per minute, and I doubt whether the three-year limit placed on the life of high-speed en- 

 gines by Mr. Shaw will be found to apply to those units after that period. Even when 

 run up to speeds as in submarine practice, the German submarine engines certainly 

 showed reliability under the tremendous stress to which they were subjected. 



No. 2, as to more major overhauls, such as lifting of cylinder covers, etc., and 

 discharge of lubricating oil from crank case — these appear to be questions of design which 

 improvements of the art are overcoming. 



No. 3, concerning 30 per cent more fuel per knot, of which 15 per cent is chargeable 

 to the higher fuel consumption of the engines — this might apply to very high-speed en- 

 gines, but not to the moderate-speed engine of comparatively large size as applied to main 

 propelling units. 



No. 4, as to lighter grade and more expensive fuel oil required — the oil that is 

 burned in auxiUary engines certainly should not differ from that burned in the main en- 

 gines, and there is no reason why just as heavy a grade of oil cannot be burned in the 

 moderately high-speed engine as in the slow-turning engine used by the authors. 



No. 5 — the same answer as for No. 2 applies. 



No. 6 depends upon the number of cylinders used and the design. 



No. 9 — if the engines are not run at too high a speed, there is no reason to expect 

 that the personnel will be overworked any more than they would on direct coupled twin- 

 screw installations. A subdivision of the total power for electric drive, if not carried too 

 far, should give satisfactory results if the engines are properly designed. 



No. 11 — the same answer would apply here as to No. 1, and in addition I might add 

 that the Worthington Pump and Machinery Corporation has over one hundred success- 



