Both instruments are constructed in a similar fashion utilizing two simple component pieces, a ruled baseplate and a rotating compass rose.
At this point in time the most important elements we need to concern ourselves with our the course and direction of bearing line, the rotating compass rose, and the meridians of longitude that run from North to South on a navigation chart.
In this first example we will use the plotter to measure the true course we have laid off between point A due North of The Wallet Buoy No. 4 and B Due North of the Wallet Buoy No. 2
Please note this is True Course between points A and B and not the course to steer (CTS) or the course made good (CMG) as no magnetic variation or deviation or set and drift has been applied..