The 0 -180° line which meets the straight edge of the half-moon window at right angles, can be used to draw a right-angled cross of 1 inch legs on either side of the selected chart point.
Umgca ongu0°-180° odibana nesiphelo esithe ngqo sefestile yecala lenyanga kwi-mbombo yenyanga kwimbombo ezilungileyo zingasetyenziswa ukuzoba imbombo elungileyo egqitha i-intshi enye yenyawo kwelinye lepoyinti ekhethiweyo yetshati