Ship Range is the maximum distance a fleet can be from a planet or starbase.
Upon selecting a fleet, the 
Ship Range is visually represented by a dashed border. By holding down the Control key, a tool tip will display showing the distance the tile under the mouse cursor is from the currently selected unit.
The larger the map size, the longer the base Ship Range.
Bonuses to Ship Range
The primary way to increase Ship Range is by adding a Life support module to a ship. The 
Interstellar Travel branch provides upgrades to life support, as well as direct Ship Range bonuses.
Other bonuses include:
- The Adventuresome trait
- The Determined ability
- The Starfaring ability can construct the
Hyperion Supply System improvement - The Ship Range anomaly in the Precursor Worlds DLC
- Certain planet types construct ships with increased Ship Range in the Precursor Worlds DLC
