At first glance, it doesn't look like a fair fight: a 135-foot-long tug boat pushing a 587-foot-long tanker — all the way from South Carolina to Texas and back.
Crowley Maritime Corp. christened two of the latest additions to its fleet in downtown Charleston on Wednesday, the tanker known as "650-4" and her powerful sister ship, the tug Integrity.
The two vessels will travel back and forth between BP America plants in Texas City, Texas, near Galveston, and the petrochemical company's manufacturing site on the Cooper River in Wando. The tanker, which is a barge, can carry a payload of up to 185,000 42-gallon barrels— or more than 7.7 million gallons.
The barge does not operate under its own power. Instead, the tug propels it by using two "pins," about 4 feet in diameter, that stick out of the port and starboard sides of the Integrity's bow. The giant pins latch into notches at the stern of the barge, giving the tug a firm grip to push it along.
The arrangement, called articulated tug and barge, or ATB, allows the two vessels to pitch independently in response to waves when under way.
The 650-4 will transport a chemical called paraxylene from Texas City to the Charleston plant for conversion into purified terephthalic acid, or PTA, which is used to make polyester products such as plastic soda bottles.
BP's local plant is the largest producer of PTA in North America, said Robert Genovese, a BP division president based in Naperville, Ill., who attended the ceremony at the State Ports Authority's cruise terminal.
The christening was held in Charleston to recognize Crowley's relationship with BP, said Steven Collar, a senior vice president and general manager of the Jacksonville, Fla.-based shipping line.
The vessels will be crewed by nine Crowley personnel and chartered exclusively to BP. The journey between the East and Gulf coasts typically will take about 4 1/2 to 5 days, Genovese said, which is about a day and a half faster than with earlier-generation vessels.
Also, the 650-4's double-hull construction helps protect against environmental damage should the tanker become involved in an accident, Genovese said.
The tanker, still spotless and clean after three voyages, took three years to build at the VT Halter Marine yard in Pascagoula, Miss.
"It's a huge piece of equipment," said Tom B. Crowley Jr., Crowley's president, chairman and chief executive.