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follow the crack and seek easier ones than to attempt to break tlie 

 heavy ice and proceed directly into the next lead. While the convoy 

 is often led on a directly opposite course, going from lead to lead, it 

 should proceed in the required general direction. 



In zones of close pack, there are places where an icebreaker cannot 

 penetrate. The gi-eat amount of friction created by the ice against 

 the icebreaker's sides may hinder her advance causing her to stop. 

 The power of the engines in these cases is insufficient and the ship 

 gradually loses way. Such ice can be broken only by backing and 

 ramming. 



From the thickness and compactness of the ice, the captain of the 

 icebreaker determines the distance from which he nnist start tlie ice- 

 breaker in order to attain sufficient momentum required for the initial 

 blow. The momentum must be added to the power of the engines, 

 since they alone cannot overcome the obstacle. Usually an icebreaker 

 backs up a distance of from 1 to 3 ship lengths, then goes full speed 

 ahead until her stem is pushed into the ice. It must be remembered 

 that the ice must be struck only by the stem and not by the turn of 

 the bow; in the latter case, the ship's hull might be damaged. If the 

 obstruction is strong and extends over a great distance, the blow must 

 be repeated for many hours in succession. 



If the ice has not been broken after one blow, the icebreaker upon 

 losing its momentum stops. As soon as the icebreaker slackens speed, 

 the engines should immediately be reversed to full speed astern. If 

 this moment is lost and the icebreaker stops in the ice while the en- 

 gines are going full speed ahead, the ship will invariably wedge in and 

 time may be lost in releasing her. When the engines are going astern, 

 the rudder must be amidships. Once clear, the icebreaker backs the 

 required distance and repeats the blow. It may be necessary to make 

 either a simple channel, equal to the width of the beam of the ice- 

 breaker, or a double or triple one, depending on the strength and 

 character of the ice. After making a channel, the icebreaker returns 

 to the ships, and if the channel remains open, the icebreaker will be 

 able to lead two or three ships at a time. If there is much ice in the 

 channel and several ships cannot pass unescorted, the ships are taken 

 through the ice one by one. 



If the condition of the ice gets worse en route, and a convoy of three 

 or four ships becomes too large, the assistance afforded by the ice- 

 breaker will be lost on the rearmost ships, which will have to be broken 

 out continually. If, in such circumstances, a radical and rapid change 

 in the condition of the weather or ice is expected, it is better to wait 



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