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to the bow turn method because it piles ice about the rudder and screw 

 of the beset vessel. 



Sometimes a vessel gets stuck in a floe of such heavy ice that the 

 icebreaker cannot reach her. In such cases, before releasing the ship, 

 the icebreaker is compelled to force the entire floe on one side or the 

 other. By thus thinning the ice and by forcing it, the icebreaker 

 eventually breaks out the ship and enables her to proceed. Often 

 w'hen such a floe is freed, there is a great separate grinding movement 

 called screwing. Screwing pack should be avoided at all costs, because 

 a ship caught in it may receive damage to her hull before the ice- 

 breaker can break her out. 



It is sometimes necessary to break the ice around the same ship 

 several times before she is freed. This situation usually occurs during 

 ice pressure, or when the ship's engines are very low-powered. The 

 above are the principal methods of breaking out single ships. How- 

 ever, it should be remembered that the other ships, left without assist- 

 ance, are usually blocked by the ice and unable to proceed on their own. 



When the ships are in column, the icebreaker can sometimes pass 

 the entire convoy on the lee side along its course at the greatest possible 

 speed, breaking it out entirely. The ships can then proceed along the 

 channel broken by the icebreaker. 



Usually if one vessel in the convoy gets stuck, they all get stuck. 

 Also, it is not always possible for the vessels in a convoy to maneuver 

 into parallel tracks. Therefore, it is necessary for the icebreaker to 

 maneuver ahead of each ship, back down on the vessel's bow, then run 

 toward the stern of the next vessel, swerving out in time to parallel 

 her, and then repeat the process. This procedure requires rapid han- 

 dling of the icebreaker because each vessel, as soon as the ice is cleared 

 ahead of her, must start moving. By the time the icebreaker reaches 

 her station ahead of the column, the entire convoy is in motion. 



While the icebreaker is breaking out a ship, the ice often cracks 

 toward the ship's sides. If the icebreaker passes her at a great speed 

 the icebreaker's bow will turn along the crack toward the ship. This 

 danger should be carefully guarded against, otherwise collision with 

 resulting damage is probable. 



In general, when passing close to a ship, the icebreaker must make 

 an estimate of the character of the ice between it and the ship. If there 

 is weak ice close to the ship, the icebreaker may be thrown against the 

 ship. Likewise, when breaking a ship out, the strength of her liull 

 must also be taken into consideration, since the icebreaker presses the 



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