Many ships in the galaxy require a large number of crew to operate them. The number of crewmen on a ship is not the number of beings required to pilot the ship, but is the number required to maintain and operate the ship for any substantial period of time.
For each week that passes without the required number of crew onboard to maintain the ship, the ship moves -1 step down the condition track. This is a persistent condition that lasts until the crew compliment has been brought up to required levels. If a ship moves to the bottom of the condition track due to lack of sufficient crew, it remains disabled until overhauled. An overhaul costs 5,000 credits times the ship’s cost modifier (pg 38, SotG).
A character may use the Jury-Rig application of the Mechanics skill to get a disabled ship moving again, thus allowing a ship disabled due to insufficient crew the ability to get to a space-dock.