OF GYRO-STABILIZER FOR SHIPS. 47 



operation of the plant have reported that they are satisfied that it is "thoroughly 

 practicable and that there will be no difficulty in keeping it in proper operating con- 

 dition." 



Fig. 8, Plate ^2, shows an elevation, partly in section, of the plant with a few 

 rough dimensions. 



Fig. 9, Plate 33, shows the gudgeons as secured to the structural steel supports. 



Fig. 10, Plate 34, shows the detail of one of the gudgeons. 



Fig. II, Plate 34, shows the detail of the shaft with principal dimensions, with 

 outline of rotor. 



Through the courtesy of the owner of the yacht automatic records of the per- 

 formance of the plant have been made, extending over a number of sea trials, in- 

 cluding also some rolling records, all of which are available for use of the Depart- 

 ment. 



The gyroscopic recorder employed to make these records is shown in Fig. 18, 

 Plate 36. 



An attachment was made to the gyro plant so that a pen upon the tape might 

 indicate the characteristic precession movements of the gyro during stabilization. 

 Fig. 12, Plate 34, shows such a curve. This is interesting as it clearly shows the 

 different magnitudes of the precession movements of the gyro as they automatically 

 adjust themselves to the neutralization of widely different wave increments apply- 

 ing forces from the sea to either side of the ship. Some of these wave increments 

 require a full precessional oscillation, others requiring only a very trifling preces- 

 sional oscillation. Instances are also seen where successive wave increments come 

 in from the same side of the ship, requiring a second oscillation in the same di- 

 rection for their quenching. 



This diagram also shows another interesting feature, namely, how the forces of 

 the sea arriving first on one side of the ship and then on the other are transmitted 

 through the structure of the ship to the gyro equipment in the form of static forces, 

 causing very great disturbances and activities of the gyro equipment, while the ship 

 through which these forces are transmitted stands practically quiescent and free 

 from motion (other than the incipient rolls necessary to actuate the little control 

 contacts). 



Fig. 13, Plate 35, shows records taken while the stabilizer was rolling the 

 boat, with the gyro wheel spinning only 1,100 revolutions per minute. This rec- 

 ord indicates that the gyro running at this speed was enabled to impart to the 

 yacht only a trifle over a degree per cycle of the oscillations of the gyro, and this 

 only in the middle of the roll ; an amplitude was quickly reached beyond which 

 the precession motor was unable to oscillate the gyro at sufficient amplitude to in- 

 crease the rolling of the ship. At this point a balance is struck, the energization of 

 the ship from the gyro is just equaling the natural friction increment of the yacht 

 for this amplitude. The back reaction of the movement of the ship gradually cut- 

 ting down the oscillating amplitude of the gyro against the precession motor is also 

 clearly seen in this figure. 



