With 60 percent of the Delaware River navigation channel now at or deeper than 45 feet, steamship lines and port officials say the dredging will do two things:

Put more cargo on ships currently coming into the ports of Wilmington, Philadelphia, and South Jersey, and allow larger ships from Asia to sail the river when the Panama Canal expansion is completed in 2015.

It's been 30 years since Congress directed the Army Corps of Engineers to investigate the feasibility of deepening the channel from 40 feet to 45.

Since the project began in March 2010, 42 miles of the 102-mile channel from Camden to the Atlantic Ocean have been deepened. Thirty-five miles are already naturally at or below 45 feet, which leaves about 25 miles left to be dredged.

The result will be "bigger ships, and more ships, coming up the river," said Stuart Jablon, Dole Fresh Fruit Co.'s vice president of operations in Wilmington. "The longshoremen are going to benefit, the tugboat operators are going to benefit, the river pilots are going to benefit. It will make the industry healthier."

Cargo activity at public and private terminals on the Delaware in 2010 supported 134,945 jobs, generated $53 billion in economic value to Pennsylvania, New Jersey, and Delaware and $7.8 billion in wages and salaries, and contributed $781.4 million in state and local taxes, according to a study for the Maritime Exchange for the Delaware River and Bay by Martin Associates, a Lancaster-based economics consulting firm.

Currently, large ships have to be careful coming up the Delaware. Some transfer cargo onto smaller vessels, a process known as "lightering," in the Delaware Bay before coming upriver.

Hamburg Sud vessels from South America, Australia, and New Zealand get "wiggle room" with the depth restriction by waiting for high tide - which brings several feet more water, said Rainer Dehe, assistant vice president for operations.

"It was much easier in the past when fuel prices were not as high," Dehe said. "The times that you wait today until high tide sets in are extremely expensive to recover. If I wait six hours for high tide to have enough water to reach Philadelphia, or delay my sailing on the way out again, that is time that I need to compensate for somewhere."

At the current depth, a ship can carry the equivalent of 4,000 loaded 20-foot steel cargo containers, said Robert Blackburn, the Philadelphia Regional Port Authority's senior deputy executive director.

With an additional five feet, ships will be able to travel the river carrying 6,000 containers, Blackburn said.

At 11 p.m. last Sunday, the Jennifer Rickmers docked at the Packer Avenue Marine Terminal in South Philadelphia. Longshore workers unloaded commodities that included citrus fruit and raw materials used in construction and manufacturing. With a cargo capacity equivalent to 5,060 containers, the ship, if fully loaded, would require the deeper 45-foot channel.

"There is not a specific commodity that we will be able to access that we can't access now," Blackburn said. "But we will be much more attractive to steamship lines and shippers as they determine ports to call in the United States."

With deeper water, Philadelphia could be a ship's first port of call instead of second or later.

"It certainly will make the river and the ports on the river more attractive," said Dehe of Hamburg Sud. "Obviously, there are many facets that determine the flow of cargo, but the draft limitation is certainly an obstacle at times today, and the need for more water will become more pressing as we go forward."

A deeper shipping channel is key to the planned new Southport Marine Terminal at the Navy Yard in South Philadelphia.

The Delaware River Stevedores, operators of the Tioga Marine Terminal in Port Richmond, and DRS's parent companies, Ports America and SSA Marine, global marine terminal operators and stevedores, are continuing discussions with Philadelphia port officials about developing Southport.

"We are resurrecting the team and finalizing the plan for the possible development of Southport," said Robert Palaima, president of Delaware River Stevedores. "We are talking to potential carriers that would be likely candidates to come to Philadelphia. Clearly, one of the conditions was a deeper Delaware."

Ships are getting bigger, and the largest U.S. ports already have deeper water - Baltimore, Norfolk, Va., and Oakland, Calif., are dredged to 50 feet. Charleston, S.C., is at 45 feet, Savannah, Ga., 42 feet. Los Angeles soon will be deepened to 53 feet and Long Beach, Calif., to 76 feet. The Port of New York and New Jersey is being deepened to 50 feet from 45.

With China's slowing economic growth and a recession in Europe, shipping lines around the world are hurting, Palaima said. "I don't want to be Pollyanna and say everybody and his brother is interested in helping us develop a new terminal. But if anybody has their finger on the pulse of what's going on among the carriers it would be our partners," Ports America and SSA Marine.