SAVANNAH, Ga. -- Five mega ships — one as long as three-and-a-half football fields — line the wharves of this bustling port as towering cranes pluck containers stuffed with products destined for the shelves of Southeast retailers.

While tourists may know Savannah for its historic homes, ancient azaleas and leisurely charm, its port based in Garden City — about a 10-minute drive from downtown — also happens to be the second-largest container port on the East Coast.

Too large to transit the Panama Canal, the ships known as post-Panamax vessels have arrived in Savannah’s river port via the Suez Canal and with the help of high tide. It helps, too, that they are not fully loaded.

“The Panama Canal has always been a speed bump for us,’’ said Curtis J. Foltz, executive director of the Georgia Ports Authority.

But not content to rely on the vagaries of tides and light loads, Savannah wants to dredge its 42-foot-deep channel to a depth of 47 feet — deep enough to handle the big ships that will transit the Panama Canal once its expansion is completed in 2015.

That’s 40 miles of dredging from the Atlantic to Garden City — and it doesn’t come cheap. It adds up to $652 million, with the federal government expected to chip in about 60 percent.

Savannah is hoping to win big when the canal expansion is completed, but so are Miami, Port Everglades, Jacksonville and ports from Houston to New York, which want to attract the big ships that can carry more than twice as many containers as the vessels that now transit the canal.

There will be winners and losers, but no one wants to be left out of the race as ports arm themselves with deeper harbors, stronger wharves, larger cranes and other improvements in hopes of snagging the big ships.

Norfolk, Va., and Baltimore already have harbors deep enough to handle the super-size ships, but Baltimore needs to overcome transportation bottlenecks once the containers reach port. The Port Authority of New York and New Jersey expects to have its harbor deepened to 50 feet by 2014, but it still must raise the deck of the Bayonne Bridge 64 feet above the roadway so the ships can reach the port’s main terminals.

“If all the ports are preparing, you’re probably going to get excess capacity,’’ said Daniel L. Gardner, president of Los Angeles consulting firm Trade Facilitators and a logistics expert. “There may be a few white elephants decorating the East Coast.’’

There’s a limited pot of federal money for the expensive channel deepening projects and Florida reached into its own pocket to help finance the Miami dredging project when federal funds didn’t materialize.

During congressional testimony last year, Paul Anderson, chief executive of the Jacksonville Port Authority, lamented that the federal government has bestowed “step-child” status on the nation’s ports for too long and argued that the United States needs to invest in them.

The typical American consumer, he said, “gives little thought to how products move to the shelf at their local supercenter or mega-grocery or mom and pop, how the item we need is ready for purchase as we dash in to grab that container of coffee or computer part … I shudder to think of the outcry should our consumer products get stuck on the docks because we no longer have the infrastructure to move them.’’