49 



(q) That growlers and very small bergs did nbt reflect the sound 

 very well under normal conditions. 



(r) That the hulls of vessels will reflect the sound as, in a number 

 of cases, the hulls of fishing vessels in shallow water, reflected echoes 

 at 1,000 yards and less. 



(s) That hard bottom gave better echoes than soft. That a 

 variable contour bottom caused considerable trouble in determining 

 proper depths in both methods. 



U) That sloping bottom caused erratic soundings. 



RECOMMENDATIONS 



(a) That further experiments be carried out with the sonic 

 apparatus. 



(6) That a number of the crew of the Tampa be given instruction 

 in the use of the sonic. 



(c) That the apparatus be overhauled and placed in first-class 

 condition. 



(d) That the super sonic equipment be investigated with a view 

 of carrying out experiments with that installation. 



(e) That the forward oscillator be sheathed with cement. 



(/) That lines of sounding be run every 20° from latitude 44° 

 longitude 50° from west, south, and east, for a distance of 120 miles 

 from center at 10-mile intervals, except where abrupt changes in 

 depth are noted when the intervals should be shortened. 



OPERATION OF SONIC APPARATUS 



The apparatus worked very well during the first part of the patrol. 

 There was considerable noise in the worm, motor, and gears, and this 

 was adjusted by proper aligning. During the third cruise it was 

 found that two solenoids of the starting relays had burned out. 

 Upon the arrival of the vessel in port the apparatus was tested and 

 found in good shape. New parts were however taken on board. 

 When the vessel returned on patrol the apparatus failed to function. 

 The machine could not be started even by working the relays by 

 hand. The solenoids were removed and the apparatus tested and it 

 was found that the solenoids were shorted and the bank resistance 

 in the first starting stage burned out. 



The type of starter used must necessarily have a long time interval 

 from to full speed. Due to line voltage, this interval was nearly 

 one minute. As the location of the remote control was in the chart 

 room, it was rather difficult at times for the operator to tell when the 

 machine was up to speed. If a load was given the machine before 

 it was up to speed, the time interval in starting was increased. By 

 increasing this time interval, additional load was thrown on the 



