The thing is, we aren't currently able to keep a stable acceleration of 1g.
The ship's mass will also increase relativistic-ally, as it will reach a maximum speed of ~0.9999961c, so more mass will require more force for the same acceleration.
The ship's mass will also increase relativistic-ally, as it will reach a maximum speed of ~0.9999961c, so more mass will require more force for the same acceleration.