This instrument is also used for plotting courses and bearings, but has the disadvantage that the area of the chart covered by the fixed perspex square is not available for plotting.
Esi sixhobo sikwasetyenziswa ekuzobeni iindlela neempawu, kodwa inokungalungi ekubeni indawo ye chart egqunywe engesikweni sesigxina esibonisayo ayifumaneki ekuzobeni.