jgnfld wrote:Keith_w wrote:...
When there was a discussion about teaching navigation and the new math, I seem to recall that Charisian captains sailed by memory (log books), wind and currents.
As for the sky, I don't recall any mention of any pre-sextant methods of measuring the angle between celestial objects and the horizon such as Back-Staffs, or Cross-Staffs for determining latitude, (nor timers to determine longitude) so it may be possible that they didn't spend all that much time looking at the stars. I do recall mention that Charisian captains were more likely to dare the open ocean than other nations galley captains who were more likely to hug coasts while sailing to their destination.
In equatorial waters it is hypothesized that Polynesian navigators used lunar, solar, stellar cues based on rising and setting points on the horizon. That said, I suspect what was in the DW's mind is sailing based on rutters which was popular early in the Western commercial age. These were compilations of sailing directions including courses, times sailed, prevailing winds, coastal outlines, and the like created by pilots over time.
Indeed they did use rutters, which were basically sailing directions, just like the ones that were stored in the Royal College before it burned down.