"Scattered ice" (4 to 6 points) — in such ice, navigation is possible for all vessels, vi'ith al- 

 most no loss in speed for icebreakers and ice-breaking steamships, but with a 20 to 30 per cent 

 loss of speed for ordinary steamers. 



"Heavy" or "frequent ice" (7 to 8 points) — during navigation through such ice, icebreakers and 

 ice-breaking steamships lose 20 to 30 per cent of their speed and ordinary steamships cannot navi- 

 gate without the assistance of icebreakers. 



"Compact ice" (9 to 10 points)--the possibility of navigation in such ice is determined by the 

 thickness of the ice and the power of the icebreakers. 



In the navigational characteristics of ice which have been given, it is assumed that ice fields 

 and floes filling a given area are distributed in it equally, are sufficiently strong, and are split by 

 a ship only with difficulty so that navigation is possible mainly along the channels. It is necessary 

 to note, however, that the possibility of navigation is determined not only by the thickness and 

 point-frequency of the ice, but also by the degree of their compression. Thus, for example, seven- 

 point ice, whose ice fields and floes are wedged against each other at their corners, can prove to 

 be impassible even for powerful vessels. Compact ice can also be compressed or weakened. The 

 following examples affirm what has been said. 



In the middle of February, 1938, the icebreaker Ermak traveled from Kronstadt to the Baltic 

 Sea without any special difficulties. From the beginning of March, when returning to Kronstadt, 

 the Ermak had such difficulty in forcing the ice 50 to 70 m thick that it was feared there would not 

 be enough coal, and we were forced to return to Tallin for refueling. In March, the ice was neither 

 more durable nor thicker than in February. 



LITERATURE: 23, 62, 77. 



Section 47. Fast Ice 



As has already been said, fast ice, during the winter, borders shores, islands, and also ice 

 standing in shallows . 



The initial form of fast ice is "new shore ice, " which forms first of all along the shores of 

 bays, fjords, and straits well protected from winds and waves. Gradually, new shore ice, when 

 increasing in thickness, extends further and further from the shore, (including in it the ice which 

 had formed in the sea itself), and in narrow places, it reaches fast ice stretching from other 

 shores. 



At first, while the fast ice is thin, it is frequently broken by currents, tidal phenomena, and 

 particularly by heaping and scattering winds. Scattering winds break considerable areas of ice 

 from the edge of the fast ice. When the scattering winds change to heaping winds, the parts which 

 are broken off from the fast ice and also the floating ice return. At this, the sea-side edge of the 

 ice undergoes hummocking, and the parts broken off from the fast ice, along with the floe ice 

 blown against the fast ice, freeze to the fast ice, thus increasing its area. 



112 



