Planning and Constructing Restricted Water Tracks, Continued
Red and Yellow
Red soundings are defined as the minimum depth beneath the keel that
the CO deems acceptable. For example, the CO may desire that the
ships draft + 3 feet equal the value for red soundings. For a ship with
a draft of 30', the red sounding would equal 33'. This means that at no
time may the ship enter water with a depth of less than 33'
Yellow soundings are defined as the depth beneath the keel that
indicates potential danger. This depth is also determined by the CO. It
may be the ships draft + 6 feet.
Red and yellow soundings are marked on the chart using a fine felt tip
marker of the correct color (red or yellow). After studying the charted
depths, freehand draw the red and yellow soundings limits. The result
will yield a red or yellow line similar to a fathom curve.
All prominent NAVAIDS must be highlighted in yellow. This includes
any radar navigation points that are selected for use. Radar points
should be labeled beginning with the letter A in the direction of travel.
Turn bearings and ranges indicate the instant at which the rudder is put
over to execute a left or right turn. Turn bearings and ranges are created
by using the advance and transfer quantities (see fig. 12-4) of your
ships handling characteristics to plot a point on your track to which a
bearing line or range arc is laid to a prominent NAVAID. A lighted
NAVAID is best for day and night versatility for bearing lines only.
The NAVAID should be as nearly perpendicular to the ships track as
possible. In narrow channels or tight turns the ships transfer quantity
must be closely considered when laying the turn bearing or range arc.
See figure 12-5.
Turn ranges present a few differences from turn bearings. The turn
range is an arc segment and should be identified on the primary chart by
a unique color or plotted only on the CIC secondary plot chart. If the
use of turn ranges is necessary, for example, fog restricted visibility, the
navigator will normally shift his or her station to the CIC secondary
The slide bar technique is accomplished by paralleling the next intended
course to the ships actual course. By doing this, the turn bearing can
be easily revised as shown in figure 12-5.