Sublight propulsion

The rag tag fleet of the Original Series traveling at sublight (Saga of a Star World).

Sublight propulsion is the opposite of the apparent faster-than-light propulsion used by many Colonial military and civilian vessels. Essentially, the term "sub-light engines" refers to a ship's conventional drives used for leaving and attaining planetary orbits or traveling short distances. All ships have some manner of sublight flight ability, but any ship that cannot perform a Jump has sub-light flight ability only. Sublight propulsion is convenient for intra-solar system travel (such as to or from the planets that comprise the Twelve Colonies), but cannot be used for travel outside of a solar system as the time to arrive at a destination may exceed the fuel supply of the ship or the lifetime of the crew that fly the ship.

Sublight Spacecraft in the Re-Imagined Series

Spacecraft in the re-imagined Battlestar Galactica universe with sub-light flight ability include the Viper fighter craft and shuttles. There were also many other sublight vessels gathered by President Laura Roslin in the midst of the Cylon Attack in hopes of evacuating them to other civilian vessels with FTL ability. Unfortunately, an imminent Cylon attack did not allow such a transfer in time, and sublight ships such as the Botanical Cruiser were left behind to their doom as the FTL-capable ships made a rendezvous with battlestar Galactica at Ragnar Anchorage (Miniseries).

Sublight Spacecraft in the Original Series

In the Original Series, Battlestar Galactica was the only spacecraft in the refugee Colonial fleet with FTL (or "lightspeed") ability. Normally, Galactica would only travel as fast as the slowest sublight vessel in the rag-tag fleet.

Fuel

Ships in both Original Series and Re-imagined Series use the refined material known as tylium as fuel.