Idle
From BotE Wiki
The more ships a player has, the more effort is takes to watch and coordinate them.
Computer
For easier ship management Hotkey "n" is available, which jumps through idle ships (minimum one ship must be idle in the sector). Key "n" works after clicking into Galaxy Map.
Tablet/Mobile
There is no "n" available for such devices (maybe with a connected keyboard there is -unconfirmed-). To jump through idle ships click the Empire icon under Options button.
When you have too many ships
It may be better to look at the Ships overview instead.