
256
RADAR AND ARPA MANUAL
4 Where direct tidal inputs are not supplied (see Sec-
tions 2.6.4.4 and 6.8.1.6), use the known values of the
observing vessel's course and speed together with the
set and drift established in step 2 to construct a vector
triangle, the third side of which is the observing ves-
sel's track over the ground. Figure 6.9 includes an
example of such a triangle. The construction can be
carried out on the reflection plotter by transferring the
plot of the set and drift through the end of the plot
used to monitor the tracking of the origin, assuming
that the latter is correct. Alternatively, the construc-
tion may be carried