I'm not too familiar with the ancient history of it, but it requires an accurate clock. There's a good book called "Longitude" that goes over the development o

I'm not too familiar with the ancient history of it, but it requires an accurate clock. There's a good book called "Longitude" that goes over the development of the clock that could be used at sea. But, before then, it was well known that you could measure the altitude of Polaris to get your latitude, so ships would sail to the latitude they wanted, then turn East or West. We've had accurate star charts for a long time, Hipparcus had made accurate enough measurements to detect the Earth's slow 26,000 year wobble called precession. The key piece missing for navigation was a clock.