DISCUSSION ON MAY MEETING PAPERS. 45 



in the construction of these engines and, except in one or two cases, where certain firms 

 have scrupulously followed continental practice, the results have not been altogether suc- 

 cessful, and it has been anything but a money-making proposition. Only one or two ship- 

 owners have fleets of motor ships, while, on the other hand, firms who adhere to steam- 

 driven ships are alive to the situation and are considering the whole matter from every 

 point of view. 



Very few references are made in the paper regarding the actual manufacture of these 

 engines, but accuracy in workmanship is of the most vital importance, and unless this is 

 clearly realized the chances of success are materially lessened. 



It can be stated with certainty that this type of engine cannot be regarded in the 

 light of a manufacturing proposition ; many of these engines are most complicated in every 

 respect and are still in the experimental stages of development. 



Turning to the tables of figures comparing a steam-driven ship with a motor ship, 

 after considering the data it would seem to me that the figures are properly made to show 

 that the motor vessel is more economical in every respect. For instance : 



1. The mechanical efficiency of the motor ship is about 80 per cent of that of the 

 steamer, yet both vessels make a voyage of 15,500 knots in the same number of days, 

 whereas the authors must realize that with bad weather conditions at sea the motor ship 

 cannot maintain full speed, and estimates covering a number of days should make allow- 

 ances for such conditions. 



2. The oil consumption per shaft horse-power of the steamer is about right for satu- 

 rated steam conditions, but with superheat of 150° F. this will be reduced by at least 10 

 per cent. 



3. The oil consumption per indicated horse-power per hour, all purposes, of the motor 

 ship — namely, 0.310 poimd — is based on good trial-trip conditions, and a more conserva- 

 tive figure for a usual sea performance would be somewhere between 0.330 and 0.370 

 pound of fuel per indicated horse-power per hour, all purposes. 



For further information dealing with the results of Burmeister & Wain motor ves- 

 sels, I refer you to Engineering of February 15, 1915, where trial data and sea-going results 

 are tabulated in various lists. 



I have read over the paper by Mr. Warriner with a great deal of interest and also 

 had the pleasure of listening to the discussion, but did not have an opportunity of taking part, 

 due to the large number of speakers. It seems to me that the statement of the author in 

 the first paragraph is hardly in order. 



Mechanical reduction gears for turbine-driven vessels have fully justified all that the 

 original promoters claimed for this system, and up to the outbreak of war, in 1914, there 

 had been no serious breakdowns or setbacks with turbine reduction gears. During the 

 first two years of the war a large number of geared-turbine contracts for freight vessels 

 were secured by one or two builders in this country, and at that time these firms had prac- 

 tically no experience in manufacturing gears, with installing same in vessels, or in taking 

 care of them whilst in operation. This abnormal condition resulted in bringing about many 

 failures and breakdowns, and some of these would undoubtedly have been avoided if the 

 gear designers and builders had been more conservative in their proposals. 



On the other hand, it should not be overlooked that the chief reason for installing 

 mechanical reduction gears in such a large number of vessels was probably due to the suc- 

 cessful results obtained with this form of drive in vessels built in England. Many of the 



