The doomed duck boat that sank in a Missouri lake, killing 17 people, was built by a self-taught entrepreneur with no training in engineering, a report said.

Design Robert McDowell, the ex-owner of the sightseeing adventure company Ride the Ducks, testified in a deposition last year that he taught himself how to maintain and rebuild the duck boats even though he had only completed two years of college and had no background in mechanics, according to the Los Angeles Times, which cited court records.

McDowell came up with the design for “stretch” duck boats more than two decades ago, according to a lawsuit filed over a roadway incident in Seattle regarding a similar duck boat in 2015, the news outlet reported.

McDowell, who grew up in Branson, Mo., sold the business and its fleet of amphibious boats in 2004.

Last Thursday, one of the company’s duck boats carrying 31 passengers — including children — capsized and sank at Table Rock Lake near Branson during a ferocious thunderstorm.

The National Transportation Safety Board is investigating the cause of the tragic sinking.