navigational

All vessels. This is Avonport. Navigational warnings. There are pipelaying operations near gas leakage.

各船请注意，行警告，在气体泄露处附近有管道敷设作业。

Sophisticated instruments which were to make possible the European voyages of discovery, such as the astrolabe , the quadrant, and good navigational maps, were also developed by Muslims.

复杂的仪器使得欧洲人得以进行险,例如星盘、象限仪及好的图都是由穆斯林所发明的。