RESTRICTED 



ports. Although open water and icefields can be seen a great distance 

 from the air, the nature of the ice and its navigability often remain 

 to be determined by the vessel itself. 



Wlien working in ice, the maneuverability of a ship is reduced. At 

 the slow speeds often required, a vessel will answer her helm badly and 

 be slow in turning. A short ship turns more readily and is thus easier 

 to maneuver in ice. When the use of full power is limited, a kick at 

 full speed after the helm is put over may be found of assistance. If the 

 ship is down by the head, steering will be especially difficult. On the 

 other hand, although some protection may be offered the propeller and 

 rudder by trimming the vessel down by the stern, if overdone this 

 impairs the maneuvering properties of the ship. The bow, because of 

 its large sail area, will fall off in a moderate breeze. The result is that 

 the stern will be brought up against the ice. Stopping the engines to 

 protect the propeller results in losing headway and accelerating the 

 falling off. If way is lost entirely, the ship will gather sternway in a 



Figure 17. — U. S. C. G. C. Norfhwind breaking through ice in McClure Straits, showing 

 upended ice cakes which present a danger of fouling the propellers. 





^TRICTED 



