Bigger cargo ships are planning to call on Charleston Harbor in the coming years, prompting a string of changes to the region's maritime landscape.

One of the latest adjustments comes within the Charleston Branch Pilots Association.

Despite a few retirements planned in the coming years, the organization does not have any immediate plans to add new harbor pilots. The group is predicting that the bigger ships will mean less activity for the 20 staffers tasked with navigating the massive vessels through the local shipping channel.

Industry trends show shippers migrating to larger vessels and forming vessel-sharing alliances to save on the cost to ship cargo on a single route. Experts are predicting that will mean fewer but larger ships to carry the load of today's smaller vessels.

"It's like the railroad with transition to larger trains and more technology, and that means the need for fewer people," said Kent Gourdin, director of global logistics and transportation programs at the College of Charleston.

The scenario led to the S.C. Commissioners of Pilotage for the Port of Charleston to rule this month that more pilots are not needed, even with three mandatory retirements planned through 2017. Policy mandates that pilots retire at age 70.

The panel concluded that there was no need for a new apprenticeship, which is a three-year-long training period mandated to add a new pilot to the ranks.

The commissioners' unanimous decision Jan. 14 followed a year-end report showing a decrease in vessels that called on Charleston Harbor in 2013 and an outlook for the downward trend to continue.

"We acted on their report that there was no need for it ... there was no need to increase staffing at this time," said Henry Hay, chairman of the panel.

The five-page report says the pilots manned 2,156 vessels in the 12-month span, down roughly 1 percentage point from 2,178 in 2012 and 13.9 percent fewer than 2,505 ships in 2006.

The year-end report was presented by John E. Cameron, executive director of the Charleston Branch Pilots Association and an adviser to the commissioners.

"We only had four months of the year where we had year-over-year increase in number of ships," Cameron said following the meeting. "That validates the conclusion that for the number of ships arriving in the harbor, we are confident in our expectation that our workload will not grow and will actually decrease for some time." Cameron's presentation to the commissioners added that the size of big ships in Charleston Harbor has been on the uptick.

For example, 27 percent of all containerships that called on Charleston Harbor last year were in the post-Panamax class. That's up from 20 percent of vessels in 2012 and 15 percent in 2011, Cameron added.

Post-Panamax describes vessels too long or wide to squeeze through the current dimensions of the Panama Canal. The class of vessel can carry the equivalent of at least 8,000, 20-foot-long containers.

The pilot group's super-sizing trend echoes predictions by the State Ports Authority, which wants to deepen Charleston Harbor from 45 to 50 feet by 2018.

Charleston Harbor can receive big ships that draft 48 feet of water and carry the equivalent of more than 9,500, 20-foot, shipping containers when the tide is high enough.

The SPA has been preparing for the larger vessels by lobbying to deepen Charleston Harbor and add more shore capacity.

That includes the SPA's new $700 million container terminal planned to open in 2018 at the southern end of the old Navy base in North Charleston.

The SPA board of directors also recently approved $840,990 for the engineering firm Parsons Brinckerhoff to study improvements that will be needed to accommodate larger vessels and cranes at the Wando Welch Terminal in Mount Pleasant.

Such changes are a response to a series of key reasons why experts believe larger vessels will steam into Charleston Harbor.

That includes the Panama Canal undergoing a massive expansion project to accommodate larger vessels by 2015. Shippers such as Maersk are not waiting for the expansion but using the Suez Canal to send larger vessels to the East Coast.

Also, experts predict the raising of the Bayonne Bridge in New Jersey will remove the size restriction in the New York City metro area, therefore leading to more large vessels calling on ports along the East Coast.

As for the local harbor pilots, the policy establishes that each pilot does not go over 300 jobs in a year. The group has stayed well under the threshold.

In 2013, each pilot had 234 ship jobs, down slightly from 235 a year ago. The lowered workload is expected to continue this year with each pilot predicted to handle 229 jobs, according to the report.

Cameron said that the pilots should have enough manpower to handle the projected number of vessels coming into port. "We have plenty of extra capacity in our staffing now. The trend would have to reverse direction and increase at an unprecedented rate."

Jim Drogan, a maritime professor at State University of New York Maritime College, said there is a likelihood that vessel-sharing agreements do not mean calming on the local waterways.

"On the other hand, larger vessels could, it seems to me, result in the growth of trans-shipment activity at a port that might lead to an increase in smaller vessels serving as feeders to and from smaller ports," Drogan said in an email.

"I'm thinking here of the line haul air carrier/regional airlines model. A similar arrangement exists in the trucking industry with over-the-road and local delivery."

Reach Tyrone Richardson at 937-5550 or twitter.com/tyrichardsonPC.