Kiekhaefer introduced his own outboards, which he called Mercury motors, to enthusiastic buyers at the 1940 New York Boat Show, but the start of World War II derailed his plans once again. Kiekhaefer spent the war building chainsaw motors, but after the war he was back in the boat propulsion business. His Mercury Lightning outboard, introduced in 1947, was a two-cylinder engine that produced 10 horsepower. The Mercury Thunderbolt, a four-cylinder engine delivering 40 horsepower, followed a year later, and the six-cylinder, 60-horsepower Mark 75 was delivered in 1957.