dodo - Mariner's astrolabe

http://en.wikipedia.org/wiki/Mariner's_astrolabe

the instrument was certainly known by the end of the 15th century. The earliest known description of how to make and use a sea astrolabe comes from Martín Cortés de Albacar’s Arte de Navegar published in 1551

 The mariner's astrolabe would have replaced or complemented instruments such as the cross staff or quadrant as a navigator's instrument. The mariner's astrolabe was used until the middle or, at the latest, the end of the 17th century.

It was replaced by more accurate and easier-to-use instruments such as the Davis quadrant.