Baltic Sea Ice Climate Workshop 2005 
70 
Photos 03/1999 by the author 
Fig. 2. Swedish icebreaker YMER and Finnish multi-purpose vessel BOTNICA in ‘navigated 
ice’near lighthouse Norstromsgrund (Bay of Bothnia) and off Helsinki, respectively. 
At sea due to often changing ice conditions and as ships come from different harbours and as 
the convoys are guided not always the shortest but if possible the easiest and perhaps faster 
way, after some time the ice cover is crossed (cut) in several directions as shown on the radar 
images in Figure 3. A variety of aspects of how navigation can work on the ice cover is listed in 
Table 2. 
Aircraft SAR mosaic - Jan. 1985 RadarSat-1 Image of Jan 3, 2003 
Fig. 3. .Navigated Ice’ in the northern Bay of Bothnia. The ship tracks are mainly documented 
by straight white lines.