Complex sentence: When he took one of his early demonstration jet boats to the US, the media scoffed when he said he planned to take it up the Colorado river, but in 1960 a Hamilton jet became the first boat to travel up through the Grand Canyon.
Split into simpler sentences: When he took one of his early demonstration jet boats to the US, the media scoffed when he said planned to take it up the Colorado river. In 1960 a Hamilton jet because the first boat to travel up through the Grand Canyon.