How to Shape a course. Let us assume that we wish to sail from A to B and that A is the departure point and B is the arrival point.

Using your parrellel ruler and a pencil draw a line joining the two points A and B. This line is the track you need to follow over the seabed to arrive at point B — it is called the Ground Track. We mark this track with 2 arrow heads

The next and very important step is to check that the course you draw over the seabed is clear of any hazards such as dangerous wrecks or rocks.

Now find out how many nautical miles it is from A — B. — in other words the distance to your next point or destination.

Using your dividers you will find that the distance is 16 nautical miles.

Let’s assume that your anticipated boats speed is 8 knots.

Dividing the distance of 16 nautical miles by the boats speed of 8 knots gives us a passage from A to B of 2 hours.

If you depart from A at 0800 hours your ETA or estimated time of arrival at B

Will be 1000 hours.

Using your parallel ruler you will find that the Course to Steer is 045 degrees True.

In this example we have not allowed for either the Wind or the effects of the Tidal stream.