Chappaquiddick ferry company owner Peter Wells has called for bids to build a new Chappy ferry — a spare, as he calls it.

It would be called City of Chappaquiddick, named after a Chappy ferry going back 60 years, if it is built at all, Mr. Wells said.

It would look very much like the On Time III. But the next Chappy ferry might be built of aluminum, he said, unlike the marine plywood and fiberglass boats now in service.

The boat would resemble the other 64-foot length, three-car ferries in his fleet, Mr. Wells said. The propulsion system would be the same. It would have diesel hydraulics, 225 horse power diesel, with 32-inch propellers. “It is pretty much the same, why change it?” he said.

The reasons for a third ferry are convenience and more certainty in the service.

“So we have a spare,” Mr. Wells said. “It means we can work on the boat when we need to and not do it at night,” he said.

Mr. Wells isn’t yet certain about the business plan for the boat — that depends on the price. And he is not certain it will be aluminum. The marine plywood and fiberglass versions work fine, too.

“Boatbuilders won’t give an estimate unless they have plans,” Mr. Wells said. “We had no idea what the boat will cost. So we had to come up with real plans.”

He got those plans from an old friend, Dave Bonney, a marine naval architect with Bay Marine, in Rhode Island. “He knew the other two boats, having already done stability tests on them,” Mr. Wells said.

The project was just put out to bid. “The idea is to find out what it would cost, whether it is $300,000 or $1 million. And then we look for funding . . . to get started soon.”

Aluminum or wood, Mr. Wells said putting the boat side by side with On Time III, they should look pretty much alike. “Except maybe one will be silver, or it will be white,” he said.

In a perfect world, Mr. Wells said, he could see the vessel going into operation for next summer.

Mr. Wells said he has explored other options. “You can buy a 12-car ferry on Ebay for a dime a dozen. But it is hard finding a three-car ferry,” he said.

The City of Chappaquiddick was a 33-foot powered scow that went one direction. It was built for Tony Bettencourt sometime in 1935. The name is attributed to Vineyard Gazette writer and poet Joseph Chase Allen.