It was a small circular board on which the rhumb-lines were marked by a series of equidistant holes, representing the hour, or two hour periods during which the ship sailed on a particular compass course.
Ibiyibhodana nje engqukuva apho imigca elandelwa yinqanawa kwindlela yayo, lemigca ibiphawulwe liqela lemingxuma eqelelanisiweyo imele iyure okanye ezimbini ezihanjwe yinqanawa kwindlela ethile yekhampasi.