You are still thinking about positions and the sight of you U-boat on the Navigation Map is confusing you. Try rolling your map to Siberia for instance and do your maneuvering board work there.
Mobo work can be pretty difficult to comprehend at first. I think downloading an electronic maneuvering board might make the principles of mobo work clearer:
http://www.subsim.com/radioroom/down...do=file&id=648
The Electronic MoBo also has many tutorials with pictures on how it works.