Plot (Navigation)

A graphical representation of positions, courses, bearings or other navigational information on a chart or plotting display, or the act of creating it.

A plot may show a vessel’s fixes and dead reckoning, a planned route, a contact’s relative motion, tidal vectors, clearing bearings or danger limits. Paper-chart and electronic plotting use different tools but both depend on correct time, scale, datum, symbols and source data.

A plotted line is a model, not proof that the vessel is on it or that the route is safe. Position uncertainty, chart quality, updates, depth, traffic and cross-track monitoring must be considered and the plot revised as new observations become available.