398 HAYES— U. S. NAVY MV TYPE OF HYDROPHONE. 



U. S. S. Blakeley. 



The U. S. Destroyer Blakeley is equipped with an " acoustic- 

 blister" type of MV hydrophone which has been used continuously 

 for navigational purposes during the past year and has proved to 

 be very reliable and advantageous. Two instances will be cited : 



In June, 1919, the Blakeley was ordered to leave Philadelphia 

 and to rendezvous with four other destroyers five miles south of 

 Nantucket lightship. Upon clearing the Delaware Capes a heavy 

 fog was encountered which held during the entire run to the Nan- 

 tucket lightship. Difficulty was encountered in attempting to ob- 

 tain "fixes" by means of radio compass bearings from shore sta- 

 tions, but at a distance of 12 miles the Nantucket lightship submarine 

 bell was located and, by virtue of hydrophone bearings taken on this 

 bell, an accurate position 3 miles south of the lightship was reached 

 and a departure made for the Azores without sighting the lightship. 

 During the fog and while in the vicinity of Nantucket, the propeller 

 sounds of another vessel were picked up by the hydrophone at a 

 bearing dead ahead. The course of the Blakeley was changed and 

 the shift in bearing of the other vessel, which was not sighted, was 

 followed until the assurance was given that she was well clear. 



While en route from Pensacola to New York the B/a^^/^y passed 

 Hatteras during a certain forenoon in December, 1919, and laid a 

 course to make a landfall on Barnegat Light. Before reaching this 

 light, however, the vessel ran into a heavy fog and nothing was 

 sighted until the Ambrose lightship was picked up about 8 : 00 A.M. 

 the following morning. From the time the fog was first encoun- 

 tered the position of the Blakeley was checked by constant hydro- 

 phone soundings. A definite " fix " for latitude was obtained in 

 crossing the deep water gulley off the entrance to New York harbor 

 and the submarine bell of Ambrose lightship was picked up at a dis- 

 tance of about 7 miles, whence the ship's course was laid from bear- 

 ings obtained on the hydrophone until the lightship was brought 

 within sighting distance close abeam. The hydrophone could be 

 relied upon to give warning of the approach of steamers from 

 ahead and 15 knots speed was therefore maintained through the fog. 



