Complex sentence: His designs led to many advances which today's boat owners take for granted, but Hackers' combination of design flair and engineering brilliance led him to create the shape and style which was to become the signature look of American speedboats.
Split into simpler sentences: His designs led to many advances that today's boat owners take for granted. Hacker's combination of design flair and engineering brilliance led him to create the shape and style that was to become the signature look of American speedboats.