The availability and quick response of a new LNG escort tug and its render-recover winch set the stage for the successful ocean tow of a disabled cruise ship off the Mexican Riviera.
The 952-foot Carnival Splendor, one of Carnivalâ€™s largest ships, experienced a blackout following an aft engine room fire off Ensenada, Mexico. On board were 3,299 passengers and 1,167 crew.
|Tugboats tow the disabled Carnival Splendor into San Diego Bay after the cruise ship experienced a fire and power failure at sea. (Photo courtesy U.S. Coast Guard/Petty Officer 3rd Class Cory J. Mendenhall)|
Fortunately, the incident occurred only about 55 miles offshore from Sempra LNGâ€™s Energia Costa Azul LNG terminal where the specially equipped escort tug SMBC Monterrey is based. Servicios Maritimos de Baja California (SMBC) is a joint venture between Moran Towing Corp., based in New Canaan, Conn., and Grupo Boluda Maritime of Spain.
Advanced and powerful winch technology from Markey Machinery of Seattle aboard Monterrey played a critical role in towing the disabled cruise ship through nearly 300 miles of Pacific Ocean swells in November 2010.
The 6,600-hp RAstar class z-drive tug was designed by Robert Allan Ltd., of Vancouver, Canada, and was built by the Union Naval shipyard of Valencia, Spain. Along with four sister tugs, Monterrey serves LNG tankers calling on the terminal. Central to Monterreyâ€™s design is an innovative forward-mounted render-recover hawser winch designed and built by Markey Machinery to handle large vessels in the rough seas and 10-foot swells common along this section of the Mexican coastline.
Markey President Blaine Dempke said Monterrey took the 113,300-ton Carnival Splendor in tow from the cruise shipâ€™s bow. Assisting were two conventional z-drive tugs dispatched by Grupo Boluda Maritime Mexico: VB Coral and VB Chihuahua. VB Chihuahua assisted in the actual tow while VB Coral served as escort to Carnival Splendor.
|Markey Machineryâ€™s render-recover hawser winch is forward-mounted on the z-drive SMBC Monterrey. (Photo courtesy Markey Machinery)|
Dempke said that the nearly 300-mile, two-and-a-half-day tow to San Diego would not have been possible without Monterreyâ€™s 760-hp DESDF-48WF Class III electric winch. Designed for a maximum bollard pull of 75 tons in 10-foot seas with a render-recover speed of 328 feet/minute, the computer-assisted, asymmetrical render-recover winch is the first of its kind and the largest in the world. Its double-drum â€œwaterfallâ€ design features a powerful render-recover system that automatically keeps the line tension constant, compensating for the motion of both vessels and preventing catastrophic loads on the hawser. Tension can be pre-set and digitally selected and monitored from the wheelhouse. A single automatic line level wind serves both drums, which carry just over 600 feet of 10-inch UHMW-PE soft line.
To tow Carnival Splendor, the line from each drum was spliced together to achieve a 1,000-foot towline, Dempke said. Towing from its bow with its stern ahead, the tug averaged about 4.5 knots. Average bollard pull was about 40 tons all the way to San Diego.
â€œTo the best of my knowledge, this is the first open-ocean tow ever done using soft line,â€ Dempke said. He said that it would not have been possible to do using a conventional wire hawser. â€œWire only works due to catenary (effect),â€ he said.