Use of the parallel ruler 2

Looking at the nautical chart, lets assume you are departing from point A and you want to arrive at point B.
To determine the direction or the true course to follow from A to B, follow these steps:
Firstly, connect the two points A and B with a straight line and make sure that the course you want to follow is clear from navigation hazards and obstructions.
Secondly, line up the parallel ruler with the two points A and B.
Thirdly, move the parallel ruler, by alternating the halves, holding down one half by the handle and moving the other half, repeatedly, until you reach the nearest compass rose.