Until about the 17th century, nowhere in the world could longitude be determined at sea other than by dead reckoning. Longitude fixing only became practicable, and initially only for European navigators, following advances in instrumentation (primarily the marine chronometer and sextant) and the availability of astronomical data in the late 17th and 18th centuries. In the absence of information on longitude, latitude and azimuth determination were crucial for early Polynesian navigators, in addition to a range of other navigation strategies including the use of swells, birds and techniques to expand landfalls (e.g., Evans 2011: 55-72). Neither latitude nor azimuth could be determined exactly, and extensive use of stars was required for both. For azimuths, complex star compasses have been important throughout Polynesia