Introduction

Piloting is the navigation process required to navigate a vessel through restricted waters using sea marks and prominent land marks as direction fixpoints. Frequent determination of the vessel's position relative to the available geographic and hydrographic features must be performed in order to verify the vessel is on the planned sailing track, keeping it on a safe distance to potential hazards.

Coastal mariners often use reference manuals, called "pilots" for navigating coastal waters. In addition to providing descriptions of shipping channels and coastal profiles, they discuss weather, currents and other topics of interest to mariners.


Dead Reckoning allows a navigator to determine his present position by projecting his past courses and speeds over ground starting from a known and verified past position. With the same technique he can also determine his future position by projecting the current course and speed from a present position. It is generally accepted that only course and speed determine the Dead Reckoning position. Therefore, the Dead Reckoning position is only an approximate position because it does not take into account deviations such as leeway, current, compass- and steering errors.

Correcting the Dead Reckoning position for these inherent deviations results in an "Estimated Position". How close this Estimated Position is to the actual position, depends on how accurately leeway, current and steering errors can be determined for each of the stretches involved in determining the Dead Reckoning position.