Navigation aid with compass rose has detachable extension which can be fitted when compass is being used for charting and detached when it is being used to measure bearing

摘要

Two-part compact navigation aid made from transparent plastic has a first part with a graduated slider and swallow-tail shaped recesses in which matching knobs of the second part engage. The unit can be used with just the first part that includes the compass rose for longer distances not involved with map or chart work, while it can be used with the extension for use in plotting courses.