One of the two contemporary FTL drives available for use on starships, spindrive technology is based on "classic" hyperspace theory, and was the first successfull attempt to create an artificial equivalent to Otherspace-traversing FTL.
Contrary to what one might expect, however, a spindrive does not actually propel the ship forward. Rather, its two rotating nacelles generate a graviton field by orbiting each other at high speeds. Once sufficient velocity has been achieved, the graviton field "disconnects" from normal space, creating its own miniature universe. Free from Newtonian and Eisteinian confines, the ship's normal sublight engines then propel this graviton bubble at incredible speeds relative to normal space. The disconnect from normal space also prevents time dilation.
The dangers of spindrives lie in the fickleness of the artificial field surrounding the ship during FTL speeds. Even minor mechanical or calculatory flaws can spell disaster, as there is no telling where the ship will revert to normal space. If anything happens to the drive, power supply or the FTL computer systems, the ship could pop back up anywhere. This is similar to known Otherspace malfunctions, such as the one that caused the displacement of Vanguard vessels from Val Shohob to Kreton, demonstrating that both drives work along the same lines.