The U.S. Coast Guard determined this morning that a an overturned johnboat found floating in the Charleston Harbor was unmanned.

Coast Guard officials found the 15-foot boat at around 8 a.m. in the water near the Columbus Street port terminal, according to Petty Officer Patrick Schwab.

Authorities later determined that the vessel belonged to a construction company that was completing a project on Drum Island, officials said.

The johnboat was unmanned when it broke free from the site, according to the Coast Guard. It is currently at the Charleston Maritime Center waiting for pickup.

Reach Natalie Caula Hauff at 937-5594 or