Complex sentence: The Great Depression had a devastating effect on the pleasure-boat market, but in 1935 Hacker took on a business partner, John Mcready, who quickly assumed day-to-day control of the company.
Split into simpler sentences: The Great Depression had a devastating effect on the pleasure-boat market. In 1935 Hacker took on a business partner, John Mcready, who quickly assumed day-to-day control of the company.