at a rate of knots

The ship headed off westward at a rate of knots.

轮船以极快的速度向西航行。

Meanwhile, unless the whole fleet of global capitalism sinks, the developing economies of Asia will continue to catch up at a rate of knots.

除非全球资本主义国家都放弃原有的观念，亚洲的发展中经济体仍将飞速地缩小着与发达国家之间的差距。