3. Administrative drafting, or drafting done
in support of the administrative and operational
functions of your unit, such as technical and
display charts, safety and embarkation signs,
project completions, and unit readiness graphics.
In performing drafting duties, you will be
working from sketches, field notes, or direct
instructions
Engineering
Graphic
from your drafting supervisor.
Charts and Graphs
presentation of engineering data
means using CHARTS and GRAPHS, rather than
numerical tables or word descriptions, to present
statistical engineering information. Properly
constructed, each form of chart or graph offers
a sharp, clear, visual statement about a particular
aspect or series of related facts. The visual
statement either emphasizes the numerical value
of the facts or shows the way these facts are
related, A chart or graph that emphasizes
numerical value is called quantitative; one that
emphasizes relationships is called qualitative. The
trend of an activity over a period of time, such
as the mishaps summary report of a deployed unit
rendered over a 6-mo deployment period, is more
easily remembered from the shape of a curve
describing the trend than from numerical
statistics. Successful graphic presentation of
engineering data requires as much drafting ability
as the graphic representation of engineering
objects. Lines must be sharp, opaque, well
contrasted, and of uniform weight. Letters and
figures are normally executed with the standard
lettering set according to accepted conventions.
Charts and graphs are classified as technical
or display charts.
TECHNICAL ENGINEERING CHARTS
usually are based on a series of measurements of
laboratory experiments or work activities. Such
measurements examine the quantitative relation-
ship between a set of two factors or variables. Of
the two variables, one has either a controlled or
regular variation and is called the independent
variable. The other is called the dependent
variable because its values are related to those of
the independent variable. The line connecting
plotted points is called a curve, although it may
be broken, straight, or curved. The curve
demonstrates the relationship between the
variables and permits reading approximate values
between plotted points.
DISPLAY CHARTS are organized primarily
to convey data to nontechnical audiences. The
message presents a general picture of a situation,
usually comparative. There are many varieties of
display charts, including bar charts, status charts,
and training aids. In a SEABEE battalion, display
charts are frequently used in operations and
training departments. When so used, they must
conform to minimum standards prescribed by the
command.
Any construction job involves quantities of
people, materials, and equipment. Efficient
operation and completion of the job result from
planning, organization, and supervision. Graphic
presentation of data is important. Statistics based
on the results of past jobs with similar working
conditions provide a basis for predicting the
amount of time that a proposed job will take.
These statistics offer the best possibilities for
study when presented graphically, usually in the
form of a curve. The prediction of expected
achievement usually is presented as a bar chart
and is called a time-and-work schedule, When the
scheduled work progress is compared with the
actual progress (work in place), the chart is
called a progress chart.
Drafting Guidelines
As stated earlier, there are definite guidelines
in drafting. These guidelines provide uniform
interpretation of all engineering drawings. Any
drawing prepared by or for the Navy must be
prepared following the latest military standard
(MIL-STD), Department of Defense Standard
(DOD-STD), and applicable NAVFACENGCOM
design manuals. For subjects not covered by
these references, you might refer to civilian
publications, such as the Architectural Graphic
Standards. Or, you may devise your own symbols,
provided that any nonstandard features in your
drawing are supported with adequate explanation
by notes or by legend.
Many drawings continue in use for years.
Therefore, you will have occasion to work with
drawings that contain obsolete symbols. Look for
a legend on the drawings; it should help you in
reading symbols with which you are not familiar.
If there is no legend, study the drawing carefully
and you should be able to interpret the meaning
of unfamiliar symbols and abbreviations.
DoD drawing standards, which are constantly
being updated, are published by the Assistant
Secretary of Defense (Supply and Logistics),
Office of Standardization. Any Navy activity can
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