MARBLEHEAD – Boaters approaching the Statue of Liberty in New York Harbor this summer won’t be allowed past a new security perimeter of floating buoys made by a Marblehead couple.Jim and Kathleen Norgaard, owners of Lynn Marine Supply, a chandlery at 65 Front St., won a government contract to purchase and assemble 15 anchors with chain that will keep the buoys in place.According to the U.S. Department of the Interior, “The anchors and chains will be used to maintain a security zone in lower New York Harbor around the Statue of Liberty National Monument.”The pyramidal-shaped anchors are designed to embed themselves in the harbor bottom. The largest anchor weighs 500 pounds, the others about 135 pounds.”Everything we are selling is going under water, so you really won’t be able to see what we’ve done,” said Norgaard, a former corporate executive who purchased the Marblehead business with his wife in 2008.Once the half-inch or three-quarter-inch diameter chain, anchor and swivels are assembled, the Department of the Interior will transport the devices to New York. Norgaard expects the materials will be delivered to his store within two weeks.The contract is worth about $14,000.Lynn Marine Supply, which began as a downtown Lynn business, has been operating at Tucker’s Wharf in Marblehead since 1955. When the Norgaards purchased it two years ago, the struggling enterprise was located in a ground-floor storefront across Front Street from its present site.”We have a lot more square footage in our new building,” said Norgaard, former vice president of product development at Photovac, a Waltham-based provider of hand-held instruments for monitoring volatile organic compounds in air, soil and water.”It has allowed us to expand to meet the needs of the community.”The store offers maintenance, repair and safety services to sailors, recreational boaters and commercial fishermen.