Rescuers working to free the trapped crew members wanted to send word that help was on the way. They telegraphed the message of hope from the hull of the disabled ship.

Tap, tap, tap.

Most crew members of the Golden Ray, which capsized Sunday off the coast of Georgia, were already safe. Four remained onboard Monday morning as the ship lay on its side within view of the St. Simons Island Pier.

“Eventually, (rescuers) got tap backs,” said Capt. John Reed, commander of U.S. Coast Guard sector Charleston. “Knowing that the people were alive made all the difference.”

Three of the crew members had been together on the ship and had been rescued by midday Monday. A fourth had been stuck behind glass in an engineering control room. By Monday evening, the final crew member was being escorted onto dry ground, smiling and wrapped in a blanket.

“Daylight,” he said with relief.

Georgia Ports Authority executive director Griff Lynch greeted news of the successful rescues with a word of thanks.

“Our prayers have been answered,” he said. “Right now we are working closely with the Coast Guard to reopen the channel so vessel traffic can move safely to and from our Brunswick terminals.”

The Golden Ray, a South Korean vessel registered out of the Marshall Islands, had departed the Brunswick port bound for Baltimore about 1 a.m. Sunday when a fire broke out onboard. It capsized in St. Simons Sound off the shore of St. Simons Island with 24 people aboard, including 23 crew members and a pilot from the Brunswick area. Twenty people, including the pilot, were rescued shortly thereafter.

The vessel had approximately 4,200 vehicles on board, according to the Ports Authority. The vehicles remain onboard the disabled ship

The cause of the incident remains under investigation. Authorities do not believe the ship struck anything in the water.

Meanwhile, environmental advocates were worried about the potential damage to the waterway, where crews were removing oil Monday afternoon.

“Any leak is big,” said Susan Inman of the Altamaha Riverkeeper. “This is just another blow to our coast.”

Inman, who serves as the organization’s coastkeeper, said gasoline could be smelled in the area and was visible in the water, both signs of contamination. Crews were attempting to contain oil with booms, or temporary barriers placed in the water, she said.

“This is the waterway from the islands and the mainland and the area between is a marshland, and it’s like a nursery” for a variety of different animals, Inman said.

The work was just beginning late Monday, with plans underway for eventually righting the ship and moving it, officials said. Several agencies and businesses were assisting the Coast Guard, including the Georgia Department of Natural Resources, Moran Towing, SeaTow, Brunswick Bar Pilots Association, and the Glynn County Fire Department.

“While this is only the first part of the Golden Ray and the St. Simons Sound incident, there remains a lot of work to do, threats to the environment, hazards to people and to the economy through the port of Brunswick continue to be addressed through a unified command,” Reed said.

Inman said she it will take a collaborative efforts to remove the cargo ship while also minimizing environmental impact: “It’s fair to say we have no idea how this is going to be or how long it’s going to be.”