Portland Plotter

A proprietary chartwork plotting instrument combining a rotating compass rose with straight edges and distance scales.

It is placed on a paper chart and aligned with a meridian or parallel so courses and bearings can be plotted or measured without walking parallel rulers across the chart. Versions may include common chart-scale distance markings and conversion aids.

The user must align the plotter correctly, read the intended scale and distinguish true, magnetic and compass directions. Because Portland Plotter is a product name, the generic class is a rotating navigation plotter, and equivalent instruments may use different markings or procedures.

Terms with the same meaning:

Plotter, Breton Plotter, Portland Course Plotter, Course Plotter

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