The USS Boxer -- a ship that has struggled to get to sea despite a recent overhaul -- finally managed to get underway on Thursday but seemingly suffered a problem while within sight of San Diego harbor.

The Navy denied any issue with the amphibious assault ship, but video posted online by San Diego Web Cam, a social media account that monitors the harbor, showed smoke billowing from its superstructure as it moved across the water.

"We just had an engineering casualty -- black smoke coming out the stacks," the ship radioed Thursday afternoon -- just hours after leaving her berth at Naval Station San Diego. San Diego Web Cam captured the radio exchange and spotted the smoke coming from the ship.

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Despite the radio traffic describing an "engineering casualty," Cmdr. Arlo Abrahamson, a spokesman for the Naval Surface Force, said the incident was connected to system tests.

"The boilers burn fuel which can temporarily produce black smoke, including when engineering systems are being tested during a sea trial period," Abrahamson said. "There is no current impact to the mission, and Boxer remains focused on executing its sea trials."

According to a video of the incident, the ship appeared to billow the black smoke for a few minutes. It also asked over the radio for other ships to "stay clear."

The ship has been dealing with problems for a while as it tried to deploy, though the Navy has not been forthcoming on what specifically was keeping it in port. The Boxer underwent a $200 million, two-year overhaul that ended in 2022.

After that overhaul, the Boxer briefly put to sea in June 2022 but has been in port since.

Last month, the ship was supposed to set sail on July 21 but couldn't "because of ongoing maintenance issues," Abrahamson told Military.com at the time, but he refused to go into detail, citing operational security concerns.

Although the Boxer's power plant runs on an older boiler system, black smoke is still largely regarded as problematic among mariners.

In 2016, Russia's sole aircraft carrier, the Admiral Kuznetsov, transited the English Channel while billowing black smoke. The move, while likely intended as a power play by the Russians, instead opened the country and the ship to ridicule.

The Boxer began its service in the Navy in 1995, nearly 30 years ago.

Its latest yard period upgraded the flight deck so that it could support the new F-35B Lightning II strike fighter. The ship also received work on its hull, as well as tank and mechanical work and "other shipboard improvements," according to a statement from the contractor, BAE Systems.

-- Konstantin Toropin can be reached at konstantin.toropin@military.com. Follow him on Twitter @ktoropin.

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