bound lane Track "B" and the need for a continuous patrol was obvious. 

 These two cutters maintained the patrol rotating at 17-day intervals 

 until 7 July. From 7-1 1 July the Oceanographic Vessel USCGC Evergreen, 

 (Lt. Comdr. J. H. Bruce, USCG,) which had completed the fourth and 

 last oceanographic survey, did the final patrol duty. 



On two brief occasions there was no surface patrol technically present. 

 From 11-13 May the Androscoggin was diverted to an assistance ease 

 described in the previous section. It is ironic to note that during this same 

 period occurred the only sudden eruption of ice into the effective shipping- 

 tracks. Again, from 5-9 June the Androscoggin acted as guardship for the 

 iceberg bombing experiments in the vicinity of the Virgin Bocks. 



Within the period of surface patrol (20 April 1 1 July) ice existed in the 

 effective transatlantic shipping tracks during a total of 20 days, and for 

 another 10 days ice lay within 30 miles of the track in current use. Thus, 

 over 4-1 per cent of the time which the patrol vessels spent on duty, the 

 major steamer lanes were under active ice menace. These figures apply 

 only to the United States-European tracks. The Canadian routes were 

 under constant threat. 



It is of equal significance to note that occasions existed, such as from 26 

 April to i) May, when the southern limits of ice were constantly obscured 

 by fog. Another instance which demonstrates the importance of ship- 

 board observation and patrol is from 10-26 June when only one aircraft 

 observation flight to the southern and most critical area was successful 

 and that only partially so. Fog prevailed over the areas where the patrol 

 vessels operated for 41 per cent of the time. 



During the 1959 season all ships assigned to the Patrol conducted a 

 series of precise tests and measurements to evaluate accurately the per- 

 formance of radar as a reliable aid in the detection of ice. The results of 

 these studies are presented in a special section of this Bulletin. 



The usual routine of a cutter during its patrol was to remain with the 

 southernmost or most hazardous ice known during fog and at night. 

 "Safety" messages were broadcast on 500 Kc/s. as advisable and ships 

 observed on radar to be standing into danger were warned by visual, 

 sound or radio means. During daytime periods of good visibility the 

 cutter searched for unknown or un-relocated ice. Scientific studies were 

 conducted whenever possible. 



It often became necessary for the cutter, on orders from Commander, 

 International Ice Patrol, to abandon one berg and proceed to or search 

 for another reported to be in a more critical location. The combined use 

 of aerial observation, the oceanographic survey and the sea temperature 

 program served to assure that the surface patrol was at the most ad- 

 vantageous position. 



In addition to its regular patrol cruises each cutter made one short 

 cruise devoted to radar ice detection measurements. 



The operations of the patrol cutters is summarized by the statistics 

 presented in 'Fable 1. 



