So here's the basics of how to plot using the radar:
Terms for Plotting:
E: position drawn so that the vector E-R represents your own course and speed
R: the initial position of the plotted object
M: the second/final position of the plotted object
E-R: "OuR," our course and speed. More exactly, a leg of the plotting triangle that is as
long as our distance run between plots and running along the course we are heading
E-M: "ThEM," the course and speed of the other guy. More exactly, a leg of plotting triangle
as long as the distance the other vessel ran between plots and running along their true course
R-M: "Relative Motion Line," displays the relative motion between you and the other vessel