All ships use impulse (chemical) engines to move around in space. These engines use liquid Hydrogen as fuel (H) (Green drops=1 unit, Green 10mm cubes = 5 units).
All ships move with a semi-Newtonian type of movement. They MAINTAIN their velocity and course if no corrective thrust is applied.
There is no theoretical “speed limit” for the movement of ships using their impulse engines. HOWEVER, whatever speed you’ve built up, needs to be offset when attempting to stop. Also the faster you’re going, the less turn-radius you’ll have. Add additional impulse engines to your craft to not only go faster, but turn faster.
Standard Level 1 (L1) hulls of 100 tons (10 Hull Spaces) will typically have an impulse drive that takes 2 of the 10 available hull spaces. This drive will provide enough thrust to change the trajectory of the ship by 2 hexes.
More documentation and hopefully a video or two will be coming shortly to explain this better.