When plotting a course, it is necessary to make certain mathematical adjustments in order to obtain correct
magnetic compass readings. Plotting a course is accomplished by the use of a DR Track (Dead Reckoning),
a line drawn on a chart which runs from the point of departure to the intended point of
arrival. Plotting a course is a matter of correcting conditions of variation, deviation, converting bearings,
taking into account conditions of set and drift, and other factors necessary to arrive at the intended destination.
In addition to indicating degrees of latitude and longitude, factors concerning time, speed, and distance must
also be indicated on the DR Track when plotting a course.
Magnetic compass error and magnetic compass correction of correct variation and deviation, whose corrections are normally aided with the formula solve tvmdc, can now be corrected with this navigation tool, the Course
Conversion Calculator. Solve tvmdc is a formula, which helps when making a magnetic compass correction of magnetic compass error regarding the misalignment of true north, and magnetic north,
deals directly with the magnetic compass. T = true north; V = variation in degrees between true north and magnetic north; M = the magnetic compass reading
after adjustment is made between true north and magnetic north; D = deviation of the magnetic compass as it may be affected by the magnetic forces on the boat
such as electronic devices and/or metal parts located near the magnetic compass. This navigation tool, the Course Conversion Calculator, also is used to convert
relative bearings to true bearings and to give reciprocals. The above will make plotting a course much easier and more accurate.
After only a few moments of experimentation with this navigation tool you will be able to solve tvmdc, correct magnetic compass error and make magnetic compass corrections of correct
variation and deviation, find course to steer
and convert relative bearings to true bearings easily, quickly and accurately with a turn of only three dials.
A simplified explanation of true course, the magnetic compass, compass error and compass correction of correct
variation and deviation and relative bearings is given on this navigation tool.
A clear and simple approach to determining the conditions of "set and drift" is given on the reverse side of the calculator. This navigation tool also
has a convenient ruler/straight edge to use when making arbitrary speed scales and drawing current vector triangles. These factors will also assist in plotting a course.
A video is also available from Navigation Aid which among other details, illustrates correct variation and deviation, explains solve
tvmdc and how it relates to true north and magnetic north, shows an example of relative bearings, explains magnetic compass error,
magnetic compass correction, and demonstrates the use of the Course Conversion Calculator. The video will also give a better understanding of plotting a course.
This coastal navigation tool is non-electronic, made of a durable plastic with holes made for a three ring loose leaf book and is guaranteed to be
accurate within ¼ of 1 degree, simple to use, and inexpensive. No pencil is needed when using this device.
The calculator is an incredible device that will benefit any boater, whether it be in a classroom or on a boat.
It can also be used to verify GPS or other electronic readings. The Course Conversion Calculator comes with easy to follow instructions and an
Members of the United States Coast Guard Auxiliary may purchase this calculator through their district materials center.
Click here to see a Product Review and a Video Demonstration of the Calculator.