THE INTERNATIONAL ICE PATROL 



1935 



The International Ice Patrol is 22 years old. The present organi- 

 zation is the result of these years of experience, experimentation and 

 study. New methods and better organization are the aims of the 

 future and this seems an opportune time for a review of the many 

 problems of the Ice Patrol and of the efforts in the past to solve them. 



At some time between the last days of February and the first of 

 April, usually around the middle of March, vessels crossing the 

 Atlantic bound for Canadian ports begin to report patches of field 

 ice and icebergs moving down from the north. The first ice is usually 

 reported in the vicinity of the place where the Canadian track F 

 crosses the 100-fathom curve about 120 miles east-northeast of St. 

 John's, Newfoundland. Field ice in this region is the first indica- 

 tion that the vast areas of pack ice along the Labrador coast to the 

 northward are beginning to break up and move south. Not long 

 after these early reports are received the Coast Guard cutter afi-ives 

 and begins the annual ice-patrol season. The region which comes 

 under the scrutiny of the Patrol for the study of ice movements, 

 here called the Ice Patrol area, lies between latitudes 39° N. and 

 49° N. and longitudes 42° W. and 60° W. The principal activities 

 of the patrol are concentrated to the southeast of Newfoundland, 

 outside of the 50-fathom curve, between latitude 41° N. and latitude 

 46° N. ; bounded on the east by the forty-sixth meridian, and on the 

 west by the fifty-second meridian. The most critical area, which 

 is within this principal region of activity, lies along the eastern and 

 southern slopes of the Grand Banks south of latitude 44° N. be- 

 tween the 50-fathom curve and a line 60 miles outside thereof 

 extending west to longitude 52° W. (See fig. 1.) The extent of sea 

 ihat any one ship can search thoroughly being limited, the Patrol 

 vessel is constrained to spend almost her entire time within the 

 principal region of activity, and must scout out the critical area every 

 3 or 4 days. The "critical area" is so called because icebergs found 

 in this area are potential obstructions along tracks B and C. Under 

 normal conditions such bergs will, within a period of 2 days, cross 

 track C and in 3 or 4 days cross track B. It is in this region that the 

 most rapid change in current takes place, and it must be closely 

 watched. This last area cannot be rigidly defined, because its limit- 

 ing lines are continually changing from year to 3'ear, week to week, 



(1) 



