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CHAPTER X 



OPERATING AN ICEBREAKER 



This chapter is based on the operating experience of the Wind class 

 icebreakers, the characteristics of which are given on x^age 13, Seven 

 of these ships were built at San Pedro by the Western Pipe & Steel 

 Co. The first three were transferred to the Soviet Union under Lend 

 Lease ; two were taken over by the United States Coast Guard as the 

 Northwind and Eastioind; and the last two became the Bwrton Island 

 (AGB 1) and Edisto ( AGB 2) of the United States Navy. They dis- 

 place 6,465 tons on a full load draft of 29 feet, which places the pro- 

 pellers about 20 feet below the surface, 



PROPELLERS 



The propellers are of cast steel, with detachable blades bolted to the 

 hub, and are about 1 inch thicker than standard blades. The Burton 

 Island reported that many times while working pack in the Antarctic 

 in 1948 the propellers were fouled to the point where the main motor 

 would stall. As soon as they were clear, the ship would again resume 

 normal operations without any apparant damage having been done 

 the screws. 



As already mentioned, this class was designed to have a bow pro- 

 peller. The Northwind''s propeller was damaged by grounding in 

 the Arctic in the summer of 1946 and subsequent contacts with ice 

 wrecked the thrust bearing and threatened damage to the motor. The 

 bow propeller was therefore omitted from the Burton Island and 

 Edisto. On Operation HIGH JUMP, later that year, one ship re- 

 ported that the bow screw was unnecessary while the other, experienc- 

 ing some difficulty in clearing the broken ice from the ship's track 

 when traversing solid pack, expressed the opinion that a bow screw 

 would help lay the broken ice back upon the adjacent ice, leaving 

 a clear path. 



The bow propeller has been successfully used on the winter ice 

 of the Great Lakes, the St. Lawrence, and the Gulf of Bothnia. How- 

 ever, this is local winter ice with an average thickness of 3 to 4 feet, 

 although rafted ice up to 30 feet is said to be sometimes encountered. 



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