How Fast to Travel Through Space

To travel through space efficiently a space vessel would have to move at a high velocity. The speed limit would depend on the mass of the vessel per the energy it can produce. The time traveled would be determined by the distance traveled. Time dilation does not occur with velocity because time is a separate quality then velocity. The same amount of time would pass for the observed object, then for the observer. The mass of the space vessel would not increase because velocity increases momentum, not mass. Mass times speed equals momentum, and the momentum would be a finite number at any velocity. I didn't say the space vessel could move faster then light, because I don't know that. Velocity would be determined by how much energy can be generated for the propulsion.

I remember this spaceship which can hit speeds of 47,000 km/h.

On another note, I've always wondered, and maybe someone here can answer this for me, in space there is no gravity, so does mass affect speed in space?