A local entrepreneur who passed away recently, James M. Knott Sr. transformed the lobstering industry. And the company he founded in 1980, Northbridge-based Riverdale Mills, continues to do well under the leadership of his son, James Jr.

Before getting into the fascinating story of Riverdale Mills, I should mention why this story caught my attention. For generations, my family has been visiting Gloucester’s Good Harbor Beach – and if you haven’t been there, I can highly recommend it.

If you have been there, you know that Good Harbor Beach is mostly public — but across from Salt Island there is a strip of beach, called Briar Neck, that is private above the high-water mark. As a teenager, I was friends with a family that owned a house on Salt Island Road, which overlooks the island. I used to dive for lobsters at high tide — scooping them off the sandy-bottomed area between the beach and the island and into a mesh bag.

And I remember that my friend there mentioned the name of Janet Knott — who was then a photographer with The Boston Globe. I don’t remember why my friend mentioned Ms. Knott, and I never met her or her family.

Yet when I read Mr. Knott’s obituary on Aug. 26, I wondered whether he was any relation to Ms. Knott – and discovered that he was her father.

I had something in common with Mr. Knott — we both caught lobsters in Gloucester. But he did it in a much more commercial setting than I did. As the Wall Street Journal reported, when he was a teenager he fished for lobsters near his family’s summer cottage in Gloucester and recalled “hauling 125-pound wooden lobster traps up from the ocean floor.”

Mr. Knott told the Harvard Business School Bulletin that hauling those heavy traps strengthened his upper body, which helped him win a wrestling match at what was then called Governor Dummer Academy in Byfield (the school changed its name to Governor’s Academy in 2006.)

Mr. Knott studied mechanical engineering at Northeastern before transferring to Harvard, where he earned a degree in economics in 1954.

By 1980, when he started Riverdale Mills, he had enjoyed prior entrepreneurial success. After serving in the army, he founded Coatings Engineering Corp. (CEC) in South Natick to make plastic coatings for products such as pliers and stethoscopes. He sold that company to Gilbert & Bennett Manufacturinh Co. (G & B) of Georgetown, Connecticut, in 1962.

He was president of CEC and a director of G & B until 1978, when he left to start Riverdale Mills. He paid about $90,000 out of his own pocket for an abandoned mill in Northbridge on the banks of the Blackstone River that had made bayonets during the Civil War and converted it into a maker of PVC-coated wire, according to the Journal.

Beginning in the mid-1960s Mr. Knott experimented with wire lobster traps. He was well-acquainted with the problems of traditional wooden ones: They needed to be weighted down with rocks and bricks to keep them from floating. And once on the ocean floor, the wooden traps absorbed water — making them very heavy. Not surprisingly, Mr. Knott found that his metal lobster cages were far more durable.

Riverdale began making zinc-galvanized, plastic-coated welded wire mesh, which in the next 38 years accounted for 85 percent of all lobster traps, thanks to the superior durability of its Aquamesh product. In 2012, 70 percent of Riverdale’s sales came from selling to makers of lobster traps – there are between 8 million and 10 million such traps along the Atlantic coastline — and much of the balance of its revenues came from selling a similar product, WireWall, which was used in security fences, according to the HBS Bulletin.

It was not all smooth sailing for Riverdale. After all, it lost business to a China-based competitor that in 2000 launched a product like Aquamesh. As Mr. Knott explained to the HBS Bulletin, this rival charged 30 percent less for the product and the lobster industry bought it. Within two years, the traps rusted and the welds broke. “Our customers came back, because they realized cheaper wasn’t better,” Mr. Knott said.

The company remained competitive by using technology to boost quality. For example, Riverdale bought a $2.5 million computer-controlled welding machine that automated repetitive tasks and enabled the company to pay higher wages to a small number of trained workers and still charge lower prices than its Chinese rivals.

Indeed, Mr. Knott consistently invested in technology to boost quality and lower cost.

For example, while rehabilitating the Northbridge mill, he cannibalized parts from the printing press that a previous owner had left behind, cutting and tacking up pieces of metal and assigning a welder to assemble the parts into his manufacturing machines.

Mr. Knott kept innovating to save money as the company matured. For example, it generated electricity via hydropower, recirculated heat from its manufacturing processes to keep the factory complex warm, and cooled machinery with water from its own wells. Riverdale also fended off rivals by investing in quality control and other up-to-date equipment.

The Journal wrote that all three of Mr. Knott’s sons clashed with him when they worked for the company, and all of them quit. However, he ultimately turned over the top job in 2015 to his son James Jr. — who worked there on and off for more than 30 years.

WireWall seems to offer significant growth prospects for Riverdale. As Mr. Knott Jr. explained in an Aug. 28 interview, “The fencing market is expected to reach nearly $32.4 billion by 2022. Sales for WireWall have increased 57.2 percent annually since 2007, due to increased concerns about industrial and personal security, the superior quality of the WireWall product and Riverdale’s commitment to outstanding customer service.”