Susan Murphy revels in odd jobs. She’s performed ocean rescues in storms, oystered in the dead of winter and hand-fashioned a banjo. She’s been a postmaster and cemetery superintendent.

“My sister said to me one time, ‘You have always had a knack for picking the most unusual job,’” Ms. Murphy said.

Perhaps her strangest job — and the one everyone always asks her about — is when she towed by boat the mechanical shark for the movie Jaws. This year marks the film’s 50th anniversary of filming on the Vineyard.

In 1974, Ms. Murphy and her husband, Lynn Murphy, were hired to drag the 25-foot-long mechanical fish through the waters off Edgartown, Oak Bluffs and Katama during filming. Their job was not only to get the shark from one place to another, but also to work with the special effects department to ensure its movements felt as real — and frightening — as possible.

Mr. Murphy died in 2017.

“We never got royalties but we got a lot of good memories,” Ms. Murphy said during an interview in her kitchen in Chilmark.

Her densely-packed dining room bookshelf holds many copies of Jaws: Memories from Martha’s Vineyard, the coffee table oral history book by Matt Taylor. She and her late husband are referenced amply throughout.

The huge mechanical shark was a cumbersome beast in the water. — Edith Blake

The Murphys were tapped by Universal Studios because of Mr. Murphy’s boating experience. He did a lot of salvage work and was no stranger to rough conditions. He also helped inspire the personality of the shark-hunter Quint, played by Robert Shaw.

“They really needed somebody who knew the water and could do difficult things,” she said.

Ms. Murphy had no boating experience but her husband brought her on as first mate. She operated both the boat that towed the shark and the boat that taxied crew to and from the shore.

“​​I would have given anything to learn how to run a boat and I did that summer,” she said. “I had a film crew of 75 watching me learn . . . . It was a little nerve wracking.”

The shark was connected to the Murphys’ boat with a series of hydraulic cables, long enough so that the boat and its wake wouldn’t be visible in shots. A mechanical arm beneath the shark was added to the equation when it needed to lunge up and out of the water. The special effects department controlled the shark from the mast using a duct tape-bound panel of buttons and switches.

Producing machine-based special effects of that scale in the open ocean was an unprecedented feat. The crew came up against challenges with the shark constantly.

“They had very little time to actually test any of these things in California, and they certainly didn’t do it in the Pacific Ocean,” she said. “By the time they got here, it was like the sea trials.”

Getting the shark to move at the right time, at the right speed and in a way that audiences would find believable was a herculean set of tasks. Harsh conditions on the water meant the shark’s chassis was constantly in need of touching up to preserve continuity. All of the setbacks made for a grueling 20 weeks of filming.

State Beach during the filming of Jaws. — Edith Blake

The issues also meant cuts to the shark’s screen time ­— it is visible for only about seven minutes of the entire film. Ms. Murphy said that the shark’s unplanned absence from the screen made its presence all the more powerful.

“I think because we had difficulties with the shark, it made a better, more suspenseful movie,” she said. “They had to be stingy with it.”

As one of the few women on set, Ms. Murphy contended with challenges of her own. She said the men around her often assumed she was incapable of doing her job and would offer unsolicited help. Mr. Murphy was an important ally to her in those moments.

“All these guys would come and think they were gonna rescue me, and I’d have to yell to Lynn, ‘I’ve got help!’ and he would know that somebody was trying to interfere,” she said. “He’d say, ‘Leave her alone. She knows what she’s doing.’”

Ms. Murphy looks back fondly on her husband’s presence on set. She said he was a creative problem solver with a knack for working with machines ­— the ideal candidate for the job.

“He was brilliant,” she said.

The Murphys were just two of the countless Islanders employed by Universal that summer.

“None of us working on the movie had any idea in the world that it was going to be as big as it was,” she said. “For most of us, it was the very first movie we really had anything to do with.”

After filming concluded, the Murphys thought about moving to Los Angeles to find more work on film sets, but couldn’t bear to leave the Island behind. Though Jaws was their first and last foray into Hollywood, they will always have a place in cinematic history.

“I remember my son was taking a class on the history of film in college and he had his textbook home, and I said, ‘Oh, I wonder if they’ll mention Jaws,’” she recalled. “It was the fourth word on the first page.”