If piloting is the art of figuring your position by observing landmarks, then dead reckoning (DR) is the art of making an educated guess as to your position when no landmarks are available.

The first step in plotting a DR track is to start from a known and dependable fix. Using your parallel rulers, draw a line from where you are to where you want to go. Walk this line to the compass rose printed on the chart, and read the direction you will need to steer (course). Using your best estimate of your vessel's speed, mark off the line you've just drawn (the DR track) with ticks where you can expect to be at regular time intervals. These intervals could be minutes, hours, or days apart, depending on the length of the leg of the voyage and the speed of your vessel.

The DR track now drawn on the chart is your estimate of your boat's future progress in space AND time. It gives you the opportunity to look ahead on the chart and gauge potential hazards, and places (and times)where additional landmarks suitable for piloting observations will become available. As you travel along, continue piloting to verify your position, drawing new DR tracks after each fix. This gives you a check on how accurate your boat speed estimate was, and whether a current is pushing you off course or altering your speed.

It pays to maintain a good DR track, even if you know exactly where you are, because if conditions should suddenly change (say a fog rolls in, making piloting impossible) you will have a recent fix and some knowledge of conditions affecting your boat's course and speed to help you navigate. Remember, without making external observations, there is no way of knowing if you are being affected by a current. The DR will at least allow you to make an objective estimate and make allowances for it.

The whole point of navigating a vessel is not just to reach a certain destination, it is to keep the ship safe until you are able to find your destination.