Once the Portuguese voyages to India and the Spanish voyages to the West Indies were being regularly undertaken, mathematicians and astronomers pointed out that this was not good enough for correct navigation.
Kanye amaPortuguese kuhambo ngenqanawa ukuya eIndiya nakoma Spayini kuhambo lweqanawa ukuya kwimntla-ntshona zazisoloko zilungelelene nokuthatha, ngolwazi ngeziganga zezibalo nezazi ngenkwekwezi eyalatha ngaphandle leyo ingalunganga ngokwaneleyo ukulungisa kokuqhutywa inqanawa.