A federal map of the Port of Charleston has been expanded and updated with more details to help guide larger vessels safely through the waterway, official said.

The National Oceanic and Atmospheric Administration's new nautical chart provides details such as depth and obstructions farther east in the harbor. It also covers an additional 345 square nautical miles missing from the old map, NOAA said.

This is the first update to the local mapping since 1936.

The new navigational details were intended to help recreational boaters and harbor pilots, who steer large cargo vessels through local waters as they cruise to and from the port, officials said.

"The creation of this chart directly responds to requests made by Charleston pilots, who bring in larger ships with deeper drafts than they did when we made the original harbor chart in 1936," said Rear Admiral Gerd Glang, director of NOAA's Office of Coast Survey. "This new chart will meet current needs and, even more important, the future needs of maritime commerce in the Port of Charleston."

The new mapping comes as the State Ports Authority is seeking to deepen its shipping channel in Charleston from 45 to 50 feet to accommodate larger cargo vessels from an expanded Panama Canal.

Officials said the previous nautical chart was outdated because past deepening projects changed the sea buoy and channel entrance over nine nautical miles.

"This gives you more clarity of the water depth as you go to coastal water from truly deep ocean water," said John E. Cameron, executive director of the Charleston Branch Pilots Association.

Cameron added that the new mapping gives more details about the waters at the entrance of the shipping channel, allowing for better navigation of larger vessels.

"Ships are getting deeper and an element of that are the margins are closer to the bottom of the ocean," he said.

Contact Tyrone Richardson at 937-5550.