With the 95,000-ton cargo ship Dali powerless and hurtling helplessly toward the Francis Scott Key Bridge, the harbor pilot commanding the vessel had just minutes to make his last, desperate attempts to avoid disaster. He declared distress, dropped anchor and, notably, called for help from nearby tugboats.

Two 5,000-horsepower tugs, which only minutes earlier had helped guide the ship out of its berth at the Port of Baltimore and peeled off, quickly turned back and raced toward the Dali. But it was too late. The massive ship stacked with cargo slammed into the bridge in the predawn darkness Tuesday, toppling the span and killing six construction workers.

Whether those tugs could have averted the disaster with the Dali already out of control is debatable. But maritime experts interviewed by The Associated Press say they could have made a difference if the tugs had stuck by the ship longer, escorting it on its 18-minute trip through the port’s deep-water channel, in a position to see it drifting off course and potentially nudge or tow it back in line.

Such extended tugboat escorts aren’t required or even customary in Baltimore or at many other U.S. ports, mostly because of the costs they would add for shippers. But with the increasing size of cargo ships and the threat they pose to bridges and other critical infrastructure, some are questioning whether they should be.

“I’m a big fan of tug escorts,” said Joseph Ahlstrom, a member of the Board of Commissioners of Pilots of the State of New York, which regulates the state’s harbor pilots. “If applied early enough and effectively, yes, a tug escort could prevent a collision with the bridge or with another ship, or going aground.”

“Going to sea is danger,” added Ahlstrom, who also teaches at the State University of New York’s Maritime College. “But if you’re going to go to sea, if you’re going to put yourself at risk, do whatever it takes to minimize risk.”

Maritime experts told the AP that the Baltimore disaster highlights how each individual port makes its own tugboat rules, resulting in a patchwork across the nation, and how competition among ports for business from cost-conscious shipping companies has trumped calls for extended tugboat escorts that can add tens of thousands of dollars to every transit.

Baltimore’s port, operated by the state of Maryland, ordinarily uses tugboats to help maneuver big ships out of their docks and doesn’t require extended tugboat escorts into the port’s channel and broader Chesapeake Bay unless ordered by local harbor pilots or the U.S. Coast Guard over safety concerns tied to weather, traffic, cargo or mechanical issues. Shippers can also request tugs.

In the case of the Dali, two state harbor pilots boarded the Singaporean-flagged ship to take over navigation through the port as the vessel set out on a trip to Sri Lanka. Two tugboats, the Eric McAllister and the Bridget McAllister, guided the massive vessel out of the tight spaces of the dock and then released when the ship was safely in the channel.

But within minutes, according to satellite data that tracks vessel traffic, the 984-foot (300-meter) Dali began to drift out of its lane and veered more sharply before slamming into one of the main pillars of the bridge, which is a critical conduit for Baltimore truckers and commuters.

The National Transportation Safety Board, which is investigating the crash, said a review of the ship’s voyage data recorder showed the pilot’s 1:26 a.m. call for help from nearby tugs came about four minutes before impact.

“One of the things that was hard for me to believe is that they didn’t require tugs on the vessel as it was traversing towards the bridge,” said David Heindel, president of the Seafarers International Union, which represents U.S. merchant mariners.

“Some ports require tugs, depending on the vessel, usually tankers. You see where tugs have to escort ships in and out of port, especially narrow ports,” Heindel said. “In the end, I think that that may be exactly what happens in the Port of Baltimore.”

The Maryland Port Administration did not immediately respond to requests for comment. A U.S. Coast Guard spokesman said the service doesn’t direct tug operations in the port and the Dali’s departure “is the typical outbound scenario for these types of cargo ships.”

The Dali is owned by Grace Ocean Private Ltd. and managed by the Singapore-based Synergy Marine Group. Synergy spokesman Darrell Wilson said the pilots guide the company’s ships in and out and that he didn’t know how tugs are coordinated.

The Eric McAllister and Bridget McAllister are muscular machines. Called tractor tugs, they don’t just nudge ships. The Eric McAllister, the bigger of the two, is 98 feet (30 meters) long and equipped with a thick steel cable and winch that, when attached to even a large cargo ship, can potentially pull it away from trouble.

The 1989 Exxon Valdez disaster in Alaska’s Prince William Sound spurred Congress and a few states to require tug escorts for oil tankers. But those limited requirements were aimed at protecting wildlife from spills, not safeguarding critical infrastructure such as bridges.

Jennifer Carpenter, president of the American Waterways Operators, a trade group that represents tugboat and barge companies, said that given the Dali tragedy, she expects regulators to look closely at whether more stringent tugboat escort requirements are needed.

But she said tugboats are just one part of a complex safety matrix that also includes concrete fenders for bridges and emergency response systems.

The supply of tugboats is limited and using them more frequently entails risks, she said, primarily pollution and increased sea traffic.

“The last thing we want to do is have two tugs escorting every vessel,” Carpenter said. “That would have massive implications for the efficiency and safety of our waterways, which are already pretty crowded.”

Some ports have tried to boost vessel escort requirements. But they often face resistance from shippers, who are under pressure from customers to move goods as cheaply as possible.

In 2004, California’s Legislature passed a bill requiring tug escorts for chemical tanker ships in San Francisco Bay, but it was vetoed by then-Republican Gov. Arnold Schwarzenegger amid protests by the shipping industry over cost concerns.

“Tugs are a big upfront cost and a lot of companies don’t want to pay for that,” said Sal Mercogliano, who writes a widely followed shipping blog. “And if Baltimore starts mandating it, you’re going to see ships go to Norfolk, Philadelphia, New York — wherever is cheapest.”

McAllister Towing, which operates the tugboats that guided the Dali, can charge $15,000 or more for one or more of its ships to lead a large cargo vessel out of its berth, according to a recent rate sheet, with more charges for extended escorts.

That may be small change for a big shipping company but the costs can add up.

John Konrad, a licensed captain, said there’s an “unspoken tension” between shipping companies and pilots over how many tugboats should be used and how long they remain with a seagoing vessel.

“The pilots would like, in an ideal world, to have extra tugs with them all the time until the ship gets out to the ocean,” said Konrad, founder and CEO of gCaptain, a website for maritime professionals.

“But the shipping companies don’t want to pay for those tugs,” he said. “So there’s always this push and pull.”

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Associated Press reporter Josh Funk contributed.

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Contact AP’s global investigative team at Investigative@ap.org or https://www.ap.org/tips/