ROCKLAND – After 76 years of business, family-owned Rockland Boat will change hands this week when veteran marine supplier Hamilton Marine of Searsport closes on a purchase and sales agreement.

Atlantic Dive & Marine Supply in Southwest Harbor is also part of the purchase by Hamilton.

In 1928, the Gronros family started Rockland Boat as a wooden boat building operation.

Over the years, the company produced more than 150 vessels of all types and sizes. In the 1960s, the family turned its attention to marine supplies. The shop moved to its present location in 1993.

The family decided to sell the business “because the industry has changed so much … we thought we needed to team up with someone else,” owner Leni Gronros said Monday.

The owners of Hamilton Marine – Wayne and Loraine Hamilton – also have a family history in the marine business.

Wayne Hamilton, who opened his first store in his Searsport garage in 1976, and his wife, Loraine, now own full service marine supply stores in Searsport and Portland.

The timing of the purchase was right, said David Normann, Hamilton Marine’s sales and marketing manager. He said Gronros and Wayne Hamilton had been talking about the idea for a long time.

“It finally came together,” Normann said Monday.

Neither Normann nor Gronros would disclose the selling price.

Growth in the recreational boating population in Rockland was one of the signals for Hamilton Marine to make its move into the Rockland market, Normann said.

“What makes us different” is that Hamilton Marine caters to commercial fishermen, recreational boaters, boat builders and industrial marine concerns, whereas smaller suppliers often specialize in one area of marine supply, Normann said.

When the sale of Rockland Boat is completed, the couple will add it and a dive shop in Southwest Harbor to its growing list of stores. The latter, known as Atlantic Dive & Marine Supply, is part of the Rockland Boat deal. That store will continue to be managed by Beth Gronros.

The Rockland store, which will become Hamilton Marine, will continue to be managed by Leni Gronros, Normann said.

Although the Searsport store does not deal in dive equipment, the dive shop in Rockland will remain, Normann said, noting the retail space at the Rockland store is a bit larger than Searsport.

“It’s sort of a one-stop outfit,” Normann said, pointing to the many products carried by Hamilton Marine, from marine paints and fishing gear to safety equipment and fashionable yachting clothes.

In the coming months, the Rockland store, at 20 Park Drive, will be spruced up with interior and, eventually, exterior painting and signage, Normann said. New shelving will be installed inside and floors will be painted, he said. It may be several weeks before the store is fully stocked.

In the meantime, supplies not available in Rockland will be shipped to the Rockland store from Searsport.