In addition to megaphone, radio, and blinker
messages, various visual signals are used in beach
operations, as shown in NWP 22-3, appendix C.
Visual Emergency Signals for Boats
The following signals are visual emergencies:
OSCAR flagMan overboard
Life jacket on perpendicular boat hook
ZULU flagLoss of receive/transmit communications
GRID REFERENCE SYSTEM
LEARNING OBJECTIVES: Explain the
purpose of the grid reference system. Identify
procedures for using it.
The amphibious grid reference system is used
primarily to control waves moving in the lanes from
the rendezvous area to and across the LOD and until
they land on the assigned beach. The grid is an overlay
composed of a series of boat lanes (LOD to beach),
one for each scheduled wave. Each boat lane is marked
with the time and speeds applying to that specific
wave. A standard voice procedure is used that reduces
voice transmissions to a minimum while transmitting
accurate positions to the waves. The procedure
virtually eliminates the probability of pyramiding
vectors to the waves.
The system may also be used in the approach lanes
and enroute from the parent ship or transport area to the
rendezvous area or LOD provided frequencies are
assigned that prevent interference. Boat waves or
nonscheduled units may be guided effectively by this
system during periods of darkness or reduced visibility.
Before debarkation of the boats and amphibious
vehicles of an amphibious assault, the BGC, all
BWCs, and all wave guide officers are issued a
gridded diagram of the boat lane to be used (see fig.
12-14). The diagram is an approximate picture of the
boat lane from the rendezvous area to the beach.
Longitudinal lines in the diagram divide the lane
into three sections: L (left), C (center), and
R (right). Left and right sections are each 40
percent of the total width; the center section is
20 percent of the total width.
Lateral lines are drawn at 200-yard intervals
along the lane and are numbered to indicate
distance to go in hundreds of yards.
Lane positions are described by a letter (L, C, or
R) followed by a number of one or two digits.
Positions outside the lane are indicated by a
double letter: RR or LL.
Time lines should be plotted on the grid overlay
by the following method:
Using the given wave speed of advance (SOA)
and touchdown time, determine LOD crossing
time for that wave.
For the final l,000-yard transit, waves will be
making battle speed (BS); therefore, count
backwards from touchdown time to the BS line,
accounting for the complete time (whole
minutes and fractions).
Divide the time from LOD to BS, again
accounting for every whole minute and fraction.
Label all times on the boat lanes blank, as shown
in figure 12-14.
When more than one wave is being controlled,
the time clock will be divided into four primes:
52 l/2 to 07 l/2
1, 5, 9
07 l/2 to 22 l/2
2, 6, 10
22 l/2 to 37 1/2
3, 7, 11
37 l/2 to 52 l/2
4, 8, 12
If the 15-second primes for grid construction (and grid
position transmission) are used, the complete time for
the transit can be accounted for.
The control party has the gridded boat lanes
plotted to scale in CIC, one lane for each wave to be
tracked and controlled, to minimize confusion and
obtain a clear and concise picture of the movement of
In the rendezvous area, boats should be provided
navigational assistance to keep the waves in their
rendezvous circles. In addition, CIC tracks the waves
and fixes the position of each wave on the grid upon
the departure of the waves from the rendezvous area.
The control party then transmits the position to the
BWC by flashing light or by voice radio. The BWC,
on receipt of a grid position that indicates the wave is