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action is taken by the second icebreaker upon hearing the same sip;nal 

 from one of the ships astern, provided there are no more icebreakers 

 in the convoy. If there is a third icebreaker, she breaks out the sliips 

 following the second icebreaker. Ships must be broken out while 

 proceeding, in order not to delay the progress of the entire convoy. 

 When several icebreakers are present in line of bearing for break- 

 ing out, they follow behind the leader at a set distance to leeward in 

 such a way as to thin out the ice in the channel made by the leader, 

 and remain always in readiness for breaking out or towing any ship 

 that gets stuck or lags behind. 



DISTANCE BETWEEN SHIPS 



Prior to entering the ice, the captains of all ships must be carefully 

 briefed as to the order in which they are to follow the icebreaker. 

 They must understand the importance of maintaining the distance be- 

 tween the ships and the icebreakers and between the other ships as 

 ordered by the leader while moving in ice. Accurate station keeping 

 is essential for the safe and speedy progress of the convoy. 



If the condition of the ice is not too bad, say less than 70 percent 

 coverage, the ships can follow the icebreaker without much diffi- 

 culty. The beaminess of the latter makes it especially easy for the 

 ships closest to her, but as the channel closes in farther astern, the 

 ships at the end of the convoy encounter greater difficulties than those 

 in the van. It is, therefore, unwise to have the convoy strung out in 

 too long a line. At the same time, the distance between ships should 

 be great enough for way to be checked and collision averted if a "Stop" 

 signal is given by the icebreaker. As a rule, way can be checked in 

 clear water by going astern over a distance of 3 to 3i/^ ship lengths, 

 provided a full back bell is given. This distance should therefore be 



Figure 20. — Line of bearing for breaking-out. 



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