Yesterday, I was talking to a friend about playing a starship combat game. He's under the impression he can build a ship designed to ram another ship with minimal damage to his own vessel. I disagreed, citing the speed of the ships involved would be great enough to vaporize both ships. Okay, relative velocity counts for a lot, but the ramming ship needs to be able to move quickly enough to actually hit its target. Besides, spacecraft generally don't move at the speed of sailing ships. Who's right? Assume interplanetary flight is available, but not FTL.