Meredith said:
relative mass increases, mass according to your reference frame inside of the vehicle would remain the same.
So if someone from a planet you were passing by would measure your mass they would find it larger than if you inside your own ship would measure your mass. At near the speed of light your ship would be flatter than a dime (as viewed from a passing planet), from inside the craft all would seem normal, mass, measurement and time are all relative and change depending on relative speed.
i've always wondered: where does that relative mass come from? doesn't that contradict conservation laws?