A tugboat operator spotted the overturned 25-foot vessel at around 7:45 p.m. near Pier 70, Petty Officer Caleb Critchfield said.
The tugboat crew alerted the Coast Guard and rescued the man who was perched atop the hull, Critchfield said.
The man was taken to emergency medical responders who were waiting at the pier, he said.
The man's condition was not immediately known.
Critchfield said they have confirmed that the man who was rescued was the only person aboard the vessel when it overturned.
