TM 9-1220-238-14
Weight ....................................................... 106 lb
1-5. Tabulated Data.
b. Plotting board chest
a. Board plotting M18
Length........................................................ 44 In
Azimuth calibration.................0 to 6400 mils clockwise
Width ......................................................... 44 in
Grid scale...............................40 millimeters = 1000
Height ........................................................ 11 in
meters
Weight ....................................................... 118 lb.
Diameter (without
c. Plotting board M18 W/E
brackets) ...........................41 in
Total weight (packed in chest) ............................... 224lb
Height ....................................35 1/2 in
Section III. THEORY OF OPERATION
obtained, will depend to a large degree on the exactness
1-6. Scope.
of the operators.
This section contains the overall functional theory of
(1) If the base line 00' (fig. 1-3) Is plotted on the
the board plotting.
grid disk, and the azimuth of the target as observed
functional theory with each self test discussed
from each observation post is laid off along the lines OT
separately.
and O'T, the point of intersection of the two lines will be
the true observed position of the target The azimuth of T
1-7. Purpose.
from any point can be determined easily by measuring
The purpose of this section is to familiarize
the angle between the line connecting that point and T,
personnel with the function of the board plotting. The
and grid north line, and the horizontal range of OT or
information presented provides both a basic and a
O'T or any other desired line, can be determined readily
detailed understanding of the board plotting
by scaling off the distance, using a straightedge
graduated to the same scale as the grid disk In practice,
1-8. Functional Description.
however, the X and Y coordinates of the point are the
a. General. The theory of the plotting board is
information usually desired.
fundamentally simple, and accuracy of the results
Figure 1-3. Location of target
1-4
