Back during the winter of 2011, Dave Libby, a retired restaurateur, was sitting at his desk when he got a life-changing phone call. On the line was a Cape Cod commercial real estate agent who was sitting in the parking lot of a business he had just listed. He thought the business might interest Libby.

The business was Cape Fishermen's Supply.

When he got off the phone, Libby turned to his wife Caroline, and before he said a word, "she goes, 'go buy it,'" Libby recalled one day last week. Within a few days, Libby visited the business at 67 Depot Rd. in Chatham, and a few days after that struck a deal with owners Bob and Rosemarie Denn.

"I thought it would take a year to sell," Denn says. Today, Denn and the Libbys are seated in the office off the main room reminiscing about the business.

This month it is five years since the Libbys, who live in Dennis, acquired Fishermen's Supply. And this month it is 40 years since the business first opened its doors.

The business was established in 1976 by commercial fisherman Billy Nichols and his wife, Nancy "Peach" Nichols (later) Ryder. At that time, local fishermen had to buy their supplies in New Bedford, says Bob Ryder, who married Peach in 1980, after Billy's death in 1978. Opening the store in Chatham made life more convenient for the fishermen and also eliminated the middlemen.

Denn began working here in 1976, even before it opened, after clocking in two years as a commercial fisherman. (He now serves as an assistant shellfish warden in town.) For 16 years Denn served as Peach's manager. He and Rosemarie bought the business in 1992 and owned it for 19 years, with Rosemarie keeping the books. He now works part-time here in the spring and summer. Including the Libbys, there are four full-time employees and two part-time.

When the business first opened during that Bicentennial year, the customers were "strictly the commercial fleet-longliners, lobstermen, scallopers," Denn says. Today, along with the commercial fleet, the customers are recreational boaters and in the summer tourists who love the nautical belts and other small items such as rope knives that the store carries. The store also sells foul weather gear to landscapers and construction workers.

The Libbys had worked for several decades in the restaurant and catering businesses before retiring in 2006. But after taking some time off, they realized that while the grinding schedule of a restaurant was not for them, they wanted to manage a business. Dave had run a charter boat out of Newbury Port for about 12 years and maintains his captain's license. So a fisherman's supply business was not a huge leap. Still, when the Libbys first took over the business, they were apprehensive. Soon, though, they felt welcomed.

"I love meeting the people," Dave Libby says. "We see a lot of the same people all the time." And like Rosemarie Denn, Caroline Libby keeps the books.

The nearest direct competitor to Cape Fishermen's Supply today is still in New Bedford, Libby says. As a result, customers drive here from Provincetown and all the way down from Boston and the South Shore. The store ships all over the country- even to Alaska. "We price everything for the commercial guys so the recreational people kind of win by that," Libby says.

So to what does Libby attribute the store's 40 years of success?

First off, he says "there are very few businesses that you can buy today that have such a solid reputation and clientele." While the store continuously adapts to the industry it serves, the Libbys didn't change the business' direction. (When the Libbys took over, they created a website and a Facebook page.) The Libbys also believe in solid customer service. Today a rope is stretched out down one of the aisles - one of the store's employees is custom-splicing it. "We still offer that service that a lot of places don't," Libby says, and Caroline Libby adds, "We have a vested interest in it."

Commercial fishing has changed drastically since Denn first came to work here 40 years ago. "Today's fisherman is more business-oriented because he has to be," Denn observes. "It's a way of life and a business." Aquaculture has become a big business since 1976, and Libby stocks whatever those working in that industry need.

Libby leads a visitor through the first floor showroom with its no-nonsense graypainted floors. He points to a display of cans of bottom and topside paints. Then there is a rack of T-shirts and sweatshirts designed by Rosemarie Denn, all with the "In Cod We Trust" logo. A wall displays Grundens orange foul-weather gear. Another section is devoted to lobstering. Out back he has a line of whimsical lobster trap outdoor furniture, and in the basement, 1,000 pairs of knee and hip boots and waders.

"It's a pretty cool little operation," he says, looking at the bags he sells to the people who farm and sell oysters, mussels and clams. And "how many people get to have a whole second career where you get up every day and love it?"