The tidal vector
Now we can add out tidal vector (Fig 8.2). Unlike a Estimated Position EP where we add the tidal vector to the end of the water track, in a course to steer we position the tidal vector at the beginning of the ground track. This makes sense as we need to know how much the tidal stream will affect the vessel before we start how passage.
Remember this is different from the Estimated Position, where we are calculating our position after we have sailed the passage and therefore place the tidal vector at the end of the water track or heading plot.