General Duties of the QMOW, Continued
After each fix, you are required to make reports of the ships position to
to the OOD
the OOD. When reporting, it is normal to report whether the ship is on
track, the distance left or right of track, course and speed the ship is
making good, any set and drift encountered, recommended course and
speed changes, and estimated time of arrival at the next departure point
(A, B, C, and so on) or rendezvous.
As you can see, there is quite a bit of information to report. To gather
the required information, you will have to evaluate two or more fixes.
This is a simple task that only takes a few minutes with a little practice.
Lets break the evaluation down into sections, beginning with where the
ship is in relation to track.
As you know, a ship steers a course to follow the track to its
destination. The bow is actually always falling off left or right of course
and then the helmsman uses the rudders to correct. This is due mainly
to wind and current. Rarely does a fix fall exactly on the ships track.
To determine how far off track the ship has gotten, simply use the
dividers to measure the distance left or right, 90° to the track, and jot
down the results.
To find the course and speed made good since the last fix, use the
parallel rulers and compass rose or PMP aligned on the last two fixes to
find the course made good (CMG). Measure the distance between the
last two fixes to find the speed made good (SMG). Remember from
earlier chapters to use the time, speed, and distance triangle. Distance
divided by time equals speed. Jot down your results. We now have two
elements of our report. The next element to find is set and drift.
Set and Drift: What exactly is set and drift? Well, the term set means
the direction in which the ship is being pushed off course. Drift is the
speed or velocity that the ship is being pushed off course.
You will need recommended courses and speed changes to offset the
effects of set and drift. In some cases, it may be necessary steer several
degrees left or right of the desired course to make that course good.
Once again, keep in mind that set and drift are directly related to the
amount of wind and current. Lets work an example problem to find the
value of set and drift.