I think the Uboat icon on the map was purpousefully disabled in OLC's gui. I'm sure there are descriptions in one of his threads on how to get it back. But as a quick fix you can leave a waypoint on the map, and set a different course to ignore it. Then the end of the line points to someone very close to you.
And if you control left-click somewhere then your uboat gets panned to under your mouse cursor.