RUDDER TRIALS, U. S. S. STERRET. 333 



maximum helm-angle 32° was read off directly by an observer stationed aft 

 for that purpose. During this second turn, which occupied 82^ seconds, 

 the average revolutions while backing, but before putting the helm from 

 amidships to port, were 297.1 port and 337.1 starboard. The average 

 revolutions for a short period just after putting the helm over were 340 

 per minute port and 356 starboard, and at the end of i minute the revolu- 

 tions averaged 400 per minute on both engines. The average revolutions 

 for the turn, from the time of putting the helm over, were 378.9 per 

 minute port and 379.6 starboard. 



It is interesting to note that the maximum moment obtained on the 

 backing tests is 57.9 per cent greater than the maximum obtained at 27.0 

 knots ahead, with 35° of helm. 



After backing at full power, two turns were made at approximately 

 half of full power, the helm being put over to 35° port after the ship had 

 gathered sternway. 



On the first turn the moment rose in | minute to a value of 77,630 

 lbs. -feet and remained nearly constant for J minute, then rose slowly to 

 84,040 lbs. -feet at the end of i minute, remaining steady at that value till 

 the test was concluded. The average revolutions for i minute preceding 

 the turn were 225 per minute port and 199 per minute starboard. During 

 the turn the revolutions averaged 262 per minute port and 256 per 

 minute starboard, both being pretty uniform during the turn. 



On the second turn at reduced power, the moment rose in about | 

 minute to 88,500 lbs. -feet, then more slowly for a period of j minute to 

 95,980 lbs. -feet, the maximum; for the remaining j minute of the turn the 

 moment fluctuated between 79,980 lbs. -feet and 90,650 lbs. -feet. The 

 average revolutions during the turn were about 288 per minute port and 

 283.2 per minute starboard. 



DISCUSSION. 



The Chairman: — Gentlemen, the paper on "Rudder Trials, U. S. S. Sterrett," 

 is now open for discussion. 



Prop. W. Hovgaard, Member: — The data given in this paper I consider of 

 great interest, for experiments on this subject are, on the whole, badly needed. 

 The modern increase in speed and length of ships has necessitated the use of very 

 powerful steering gear, and experiments on such high speed vessels as destroyers 

 are, therefore, of very particular value. 



It is to be regretted that complete turning trials, including the determination 

 of the various elements of the turning circles, were not undertaken at the same time 



