General Duties of the QMOW, Continued
Allowing for Set and Drift: Once you have determined set and drift,
you can allow for it to make your desired course and speed.
Example: Lets assume that you need to make course 265° and speed
15 knots good to arrive at the desired location on time. Set and drift are
determined to be 185° at 3 knots. Use the following table and figure
11-9 for this example.
From your latest fix (A), lay out course and speed to make
From A, lay out a line in the set direction of 185° and the
amount of drift of 3 knots (3 nmi), which gives you point C.
Determine the course to steer by finding the direction between
C and B. This is equal to 276° in our example
Determine speed necessary to make 15 knots good by dividing
the distance between C and B by the time of the run.
Figure 11-9. Allowing for estimated current.
You now have the knowledge to make recommendations to the OOD.
Remember, after each fix you should make a report and any
recommended course and speed changes required. Also, when
maintaining the DR plot, always check to see that new courses ordered
by the conning are clear of obstructions. The OOD will often have to
maneuver the ship to avoid other ships.