BOSTON (AP) – The Nantucket Lightship spent more than three decades off the coasts of northern California, Maine and Massachusetts warning ships to navigate around sandbars.

Saved from the scrap heap six years ago, it’s been turned into a luxury home, and it’s now up for sale. The asking price: $7.6 million.

“We want to recover our costs,” owner Bill Golden said during a tour of the six-bedroom ship, which is docked at Rowes Wharf in Boston Harbor. “She is a museum quality artifact, a real icon of history. You can’t put a price on the history of the ship.”

Bill and Kristen Golden bought the ship on eBay for $126,100 from the state of Massachusetts. They sent it to New Bedford, where craftsmen spent three years working on it. Golden, 57, an attorney and former state senator, says they spent “millions and millions” of dollars.

With a 3-year-old son approaching school age, the Falmouth couple say it’s time to sell. They offered up a time share last year, but found no takers. Now, they’re selling the 128-foot ship outright.

“Our idea was to keep the ship historic on the exterior, and reconstruct the inside totally to give her the value to allow her to be saved,” Bill Golden said from the living room, which like the rest of the 4,000-square-foot interior features mahogany, cherry, and birch wood.

The red-painted steel hull and fog horn are among the only original parts. Everything else – plumbing, granite countertops in the galley, eight heating and air conditioning zones, six-and-a-half bathrooms, Global Positioning System navigational equipment – is new.

Lightships served as floating lighthouses off U.S. coasts beginning in the early 1800s, as commercial shipping increased. Many ships sank because they couldn’t navigate around shoals, so Congress dispatched lightships. By 1900, there were more than 50.

Golden’s ship – officially the Nantucket I – was the next-to-last built – in 1950 – and the last lightship in the service of the U.S. government, decommissioned by the Coast Guard in 1983, he said.

“Lightships today are the endangered species of lighthouses, if you will,” said Golden, an environmental lawyer and co-founder of the group Save the Harbor/Save the Bay.

There are just 14 lightships still afloat, according to Douglas Bingham, a historian for the American Lighthouse Foundation in Wells, Maine. They became obsolete as technology improved, being replaced by navigational buoys.

“That was a very important vessel in our nation’s history,” Bingham said of Golden’s lightship, which was the only one transformed into a home. “The other lightships are either museum pieces, or they’ve been converted into office spaces.”

The Nantucket was the last lightship stationed in each of its four locations – San Francisco; Blunts Reef, Ca.; Portland, Maine, and Nantucket. It was stationed off the San Francisco coast for about 20 years, spent four years in the early 70s off the Portland coast, and from 1975 to 1983 off Nantucket island.

The Secret Service used the Nantucket during President George H.W. Bush’s presidency. It was stationed off the coast of Kennebunkport, Maine, when the president was at his vacation home.

“(Bush) did go aboard several times to communicate with the White House because it had secure transmissions,” Bingham said. “Mrs. Bush hated the site of that vessel.”

The Coast Guard later gave the lightship to the state of Massachusetts, Bingham said, and he’s disappointed that the state didn’t keep it. But he said Golden has “done great things for the preservation movement.”

Finding the right asking price for such an uncommon home is difficult, said Jack Cotton, manager of Sotheby’s International Realty of Cape Cod.

“You can’t go to a computer database to find the right price. It doesn’t exist. You start high and work down,” said Cotton, himself a boat owner.

Annual maintenance, including insurance, fuel and dock fees, costs an owner between 10 and 20 percent of the sale price, he said.

“They’re absolute money pits,” he said. “But when you’re out on the water, it’s pure unadulterated joy. It extends your life. How do you put a price on that?”

Golden’s broker, Coldwell Banker’s Paul Lester, said there have been no offers made yet. Golden hopes the Nantucket ends up staying in Massachusetts.

“Mystic (Connecticut) has historic boats. Even Baltimore has historic boats,” he said. “New York has a whole seaport with many, many ships. We have the Constitution of course, but we have nothing in Boston proper.”