I love the Idea of Jump drives as the method to exceed the speed of light
Megatraveler an Traveler's drive basically caged the crew an passengers a minimum of 5 - 7 days in a pocket dimension that tunneled through jump space. No turns, no stopping, you were committed to your exit point once you pressed the big jump button
Think of finding a spy on board only trouble is they say they sent word of your destination jump mail 3 days prior, are they lying or are you all yiffed?

Another great thing about Jump is a miss-jump you could just appear back where you started, 10 times farther than the ship could normally or worst no place at all