Chris, don't forget that they could get to Zeta Reticuli system (39 light years) in 7 years ships time, assuming 1g acceleration to midpoint of voyage, and 1g deceleration the remainder, to destination. Presumedly, they could hyper-sleep through most of the voyage. Max. velocity attained based on these parameters would be 99.89% of c
Unfortunately, the total Earth-time elapsed would be 41 years.
The speed of light limit "c" is not just a good idea...it is the Law.