able. During this period a new method of target detection had 

 been developed at a rapid pace. This new method was radar. Its 

 rapid development was in a great part first due to the vital neces- 

 sity for advanced warning of the presence of enemy planes and 

 vessels in a defensive war, and later, for information which per- 

 mitted accurate gun laying under conditions which would render 

 the enemy otherwise unseen. With the advent of the plan position 

 indicator (PPI scope which presents data on a circular trace at the 

 correct range and bearing) the value of radar as an aid to naviga- 

 tion became very apparent. It was easy to see that radar would 

 have a wide use in the peacetime Navy and Merchant Marine once 

 its ability as a navigational aid was established. Considerable ex- 

 perimentation has been conducted in determining the ability of 

 radar to detect surface craft and land masses, normally hazards to 

 navigation. In the area of the Grand Banks a third danger which 

 is increased by the prevalent dense fog of that region is that of 

 floating ice in the form of icebergs, growlers and field ice. Al- 

 though much information had been gathered during the early years 

 of radar on the behavior of radar in detecting ice, no actual experi- 

 mentation had been carried out along these lines. The many re- 

 ports were conflicting in their content and lacked the quantitative 

 data such as had been gathered from other type targets. 



When the war in Europe had reached a stage where the Inter- 

 national Ice Patrol could be resumed, an experimental program on 

 the radar detection of floating ice was inaugurated. The ground 

 work for this program was laid in the late fall of 1944 and in the 

 spring of 1945. Competent authorities on the subject of radar 

 were contacted and their opinions and recommendations were the 

 base from which the program grew. The radar equipment to be 

 tested was procured and installed along with the necessary test 

 equipment on the U.S.C.G.C. Mojave, the vessel which had been 

 assigned as experimental vessel. Installation and complete check- 

 age of the gear on that vessel was completed by May, 1945, and the 

 experimental cruises were commenced late in May. Three experi- 

 mental cruises were made in 1945 from May to early August. In 

 conjunction with the shipboard work, a program of air-borne radar 

 experimentation was carried out to as great an extent as possible. 

 During the war years aircraft played an increasingly important 

 part in ice scouting and the efficiency of this scouting was greatly 

 enhanced by the use of radar. Operational commitments pro- 

 hibited the use of aircraft for the sole purpose of experimentation 

 so the work accomplished with airborne radar was primarily quali- 

 tative. Practical experience in the use of radar for ice scouting 

 was the primary consideration. 



At the end of the 1945 ice season the data obtained were analyzed 

 thoroughly in order to obtain as much information on the subject 



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