What is Dead Reckoning?

It is untrue to suggest that traditional methods of dead reckoning are no longer used as that is precisely what most modern inertial navigation systems depend upon, except that they do it electronically.

However, plotting you DR the old fashioned way is a very simple system which does not rely on any electronics or outside input.

With it you can quickly determine your present position by plotting the course and speed from a previously known position.

It can also be used to determine your future position by projecting the present course and speed from your present position.

DR positions should be plotted at regular intervals depending on the nature of the passage.

They should be updated between fixes and changes in course or speed.

Of course it's important to remember that any direct reckoning position, whether done electronically or manually is only an approximation as it does factor in tidal effects or leeway.

But by plotting the DR manually, as well as fixing your position with GPS, you will have a far better feel for where you are and how you are progressing

In m...