Dividers

A two-pointed hinged instrument used to transfer and measure distances on a chart.

The points can span two positions, step a distance along a line or transfer a measurement to the chart’s distance scale. On a Mercator chart, distance is commonly read from the latitude scale at approximately the same latitude as the measurement, not from the longitude scale.

Dividers do not measure bearings by themselves, although they can be used alongside parallel rules, a plotter or a compass rose. Their sharp points should be controlled to avoid damaging charts or injuring someone as the vessel moves.