SEARSPORT, Maine — If Wayne Hamilton hadn’t hurt his back 30 years ago loading ships, his life probably would be much the same as it is today. He’d be working on and near the water, as he still does. He’d be involved in community service work, which still occupies much of his after-work hours, and he’d be living in the town he grew up in.

But that back injury led to one big change. Hamilton now owns and operates Hamilton Marine, the largest marine supply chain north of Boston with stores in Jonesport, Southwest Harbor, Searsport, Rockland and Portland; an online and print catalog that sells products around the world; and 120 employees.

You won’t mistake Hamilton, 65, for a CEO of a company that likely sees seven-figure gross sales — he won’t say. Catching up with him for a chat means finding him between visits to his stores Downeast and shuttling a harbor pilot out to a tanker ship, a job he has done for 40 years even though it sometimes means rising in the middle of the night and piloting his boat through all kinds of weather.

He’s also the town’s harbor master, and can be seen at the town dock keeping an eye on activities in the busy summer months.

And despite his success in business, Hamilton hasn’t strayed far from his hometown. He married his high-school sweetheart, Loraine. He is president of the board of trustees for Searsport’s Penobscot Marine Museum and he serves on the board of Waldo County Healthcare.

But that injury did change the course of Hamilton’s life.

He had worked on an on-call basis at the town’s port facility at Mack Point, loading and unloading ships, supplementing his income fishing for lobster.

“It was mostly newsprint going out and tapioca coming in,” he remembers. By 1974, the back pain forced him to stop the dock work. In April 1977, “I bit the bullet and filled my garage up with gear and took a chance. It worked.”

From selling rope and other gear to his fellow lobstermen, the business grew. He bought an old building that backed against the bay downtown and opened Hamilton Marine. The store has since moved to a larger, former trucking business building east of town, with an attached warehouse that supplies the other stores and the Internet sales.

Despite the recession, sales are strong.

“Last year was very good,” Hamilton said, which he attributes to Yankee frugality, as fishermen are keeping their boats and gear repaired rather than buying new.

“We sell parts and pieces, not whole vessels,” he said. In addition, the recession has claimed some smaller marine businesses, and their customers have come his way.

Browsing at one of Hamilton Marine’s stores gives a landlubber insight into the world of commercial fishing. There’s a wide variety of rope, caulking and sealants, chains and shackles designed to hold up in the corrosive marine environment, fishing gear such as hooks and lures, anchors, knives, buckets, boots, pumps, electronics such as radios and fish finders, foul-weather apparel and survival suits.

The store also does custom rigging and cable preparation for commercial fishing boats.

In a funny story told about Hamilton’s early efforts to sell the survival suits, he would walk into a coffee shop or diner on a particularly cold day and offer to jump into the water off a nearby pier, donning one of the suits. When fishermen who agreed to watch the stunt saw how well the suits worked, they began buying them.

Hamilton has witnessed informal family reunions at his stores, as fishing families from Stonington and Swan’s Island, for example, plan on meeting at the Searsport store to pick up some items and then head out to lunch at a local restaurant.

And customers also hail from far away.

“We have customers in the Caribbean who buy flotation buoys from us,” and recreational boaters on the other side of the globe who order parts, Hamilton said. Japan also has proven to be a lucrative market.

The stores and catalog also have essentials for the recreational boat owner, and even nautical-themed books, calendars, bells, clocks and radios for nonboaters who like the sea.

A radio jingle the company used for a time referred to Hamilton Marine as “the one-stop ship shop that holds the key to the sea.” Hamilton still likes that description of his business. He also accepts the comparison with another Maine business icon, admitting that he wants to be seen as the L.L.Bean of marine equipment.

Hamilton opened the large store in Portland near the cruise ship pier in 1995. “That’s done very well,” he said.

He purchased the former Rockland Boat and a marine supply store in Southwest Harbor in 2005. In 2008, he purchased the former Church’s True Value in Jonesport.

Jonesport, a fishing town in the economically struggling Washington County, is very different from Portland, and he stocks the stores differently to meet customer needs. In fact, the Jonesport store does triple duty, carrying marine items, hardware and auto parts.

“We can adapt,” he said. “That’s what makes us unique.”

Hamilton does a lot of business with large ships, boat yards, pleasure-boat owners and ground fishermen, but feels a special kinship with lobstermen. Most recently it was low per-pound prices, but it seems lobstering is perennially buffeted by some challenge or other.

“It’s a real shame,” he said of the lobster fishery, “with the cost of bait, the cost of fuel, and the cost of equipment that the price of lobster is the same as when I was working out of a skiff in 1965.”

He feels the fishery will survive, and takes satisfaction in helping lobstermen by selling quality merchandise at bargain prices.

“I like to buy right and sell at a good price and have people feel good about what they buy,” he said.

Hamilton doesn’t worry about the business when he’s away from the store on community service or harbor pilot shuttle duty.

“You surround yourself with good people and you trust them,” he said.

Now at retirement age, Hamilton is given to reflect on his success, and expresses gratitude to both employees and customers, both of whom have been loyal to the business, he said.