Navi is the term used to refer to a vanship navigator.
A typical vanship has two seats. The pilot, who controls the vanship, sits in the front seat, while the navi sits in the back. A navi's duties include map-reading, monitoring certain instrument gauges, and communicating with other ships by means of flashing a light. In a military vanship, the navi is also responsible for reloading ammunition when it runs out.