I'll try to be as accurate as I can in explaining this

The closer to the speed of light you go the more time dilation increases 
   So if a ship was to travel for 2 hours at 99.97% the speed of light, for everyone else 81.6 hours would have passed

And as well there is no way your ship could travel at 99.97% the speed of light in matter form as far as it is known,

Better term sorced from orson scott cards enderverse "relativistic effect"~feldo