78 



ENGINEERING PROGRESS IN THE U. S. NAVY. 



Plate 31 shows curves of indicated horse-power and shaft horse-power on a 

 basis of speed for the Delaware and three turbine ships. My view is that the shaft 

 horse-power figures are practically valueless, due to the fact that torsion meters are 

 so erratic. Also, various types of torsion meters have been tried by the Navy 

 Department, which accounts largely for so great a variation in shaft horse-power 

 data of turbine ships. 



A more accurate method of comparison is arrived at by basing water con- 

 sumptions of machinery on the effective horse-power results obtained with the 

 models of vessels pulled in the experimental tank. This was our regular practice 

 before the event of the torsion meter. 



The curves on Plate 32 are based on total water consumption of machinery 

 "as measured " during the builder's trial trips. I do not consider that the Delaware 

 and the Utah can be compared accurately on an equal basis in this manner. The 

 following list gives the total steam consumption of the auxiliary machinery as 

 recorded during the trial trip results of three ships, and for the battleship Utah 

 I have estimated the auxiliary steam consumption from the turbine steam pres- 

 stures, as the water consumptions of the main engines and auxiliaries were not 

 separately measm-ed : — 



WATER CONSUMPTION TRIALS. AUXILIARY MACHINERY DATA — POUNDS PER HOUR. 



*Approximate. 



The figures given show greatly in favor of the Delaware. 



I have tabulated the auxiliary steam consumption of the scout cruisers at 

 three different speeds, which shows that the auxiliary steam consumption of a 

 turbine-driven ship and a reciprocating-engine ship are about alike. 



WATER CONSUMPTION TRIALS. AUXILIARY MACHINERY DATA — POUNDS PER HOUR. 



