But the length at the water line of a Nimitz class carrier is 1,040 feet... Based on the well known formula for hull speed(1.34x sqrt of the length of the waterline), that puts the max speed of them at about 43 knots... Or right about 50mph. While some designs allow for exceeding hull speed, It's fairly doubtful that a ship the size of an aircraft carrier can utilize those methods. It's possible that they don't have the engine power to make 43 knots, but I bet that they come very close to it.
Actually, most cats will have an estrus cycle (the technical name for heat) within six to eight weeks after giving birth. In rare occasions, a cat will have an estrus cycle within a week after her kittens were born.
Now your pregnant cat will start to have major contractions. She will be breathing deeply and you will see visible movement and shuddering of her belly. In the beginning, the contractions for cats giving birth to kittens may be once every 30 minutes and possibly longer. They gradually become more frequent and occur every 30 seconds until right before the birth of the first kitten.