Great Lakes Dredge & Dock Co. has awarded a $94 million contract to Signal International, of Mobile, Ala., to build the world’s first articulated tug/barge (ATB) dredge.
The ATB trailing suction hopper dredge would be the largest of its kind in the United States and the only ATB dredge in the world, according to Signal International.
The uniqueness of this vessel goes beyond its sheer size. “The new ATB will have a hybrid power sharing system between the tug and the barge,” said Signal International spokesman Joe Mayhall. “It will be fast thanks to its proprietary hull design and able to work in shallow water which will be perfect for beach reclamation projects.”
Trailing suction hopper dredges are designed to vacuum material from the sea floor through drag arms that load the material into the hold of the vessel. The spoil can then be transported to either an ocean disposal site where the material is discharged through an opening in the bottom of the hull or pumped ashore for beach reclamation.
The ATB dredge design will be well suited to all types of dredging, including channel deepening, maintenance dredging and coastal restoration projects with long-distance transport requirements. Great Lakes Dredge & Dock is based in Oak Brook, Ill.
Hull designs for the 15,000-cubic-yard capacity barge and 14,000-hp tug were produced jointly by Signal International, Ocean Tug & Barge Engineering and MARIN (Maritime Research Institute Netherlands), a nautical research and tank testing facility.
“Having modeled and tested many of the world’s modern hopper dredge hull forms, we are very pleased to see the Great Lakes ATB hull achieve similar speed and power results,” said MARIN’s Senior Project Manager Klaas Kooiker. “We believe this is the first ATB hull to equal ship performance capabilities.”
Great Lakes Dredge & Dock’s in-house engineering team worked closely with Massachusetts-based Ocean Tug & Barge Engineering in the design of the proprietary ship-like unit for which a patent is pending.
According to Dave Simonelli, Great Lakes’ president of dredging operations, “Our dredge is a ‘game changer’ in the competitive hopper dredging marketplace and will bring important new capacity to the U.S. hopper dredge fleet. The favorable environmental and safety features of the design, including greater fuel efficiency, green overflow systems and automated processes, were important considerations.”
The tug will be 150 feet long with a beam of 52 feet and a draft of 36 feet. The barge will have an overall length of 410 feet with a beam of 92 feet and a draft of 28 feet. The barge will be fitted with two 36-inch suction pipes and will have the ability to dredge at depths of up to 125 feet. The barge will have two electrically-operated tunnel bow thrusters for enhanced maneuverability.
The tug will be classed ABS with A1, AMS, ACC, towing vessel unlimited notations. The ATB unit will be built to U.S. Coast Guard specification for Dual Mode ITB (integrated tug barge). The tug and barge will be fitted with an Articouple FRC 90 connection system.
The vessel will be equipped with a dynamic positioning system and EPA Tier III compliant engines to minimize emissions. At a draft of 28 feet fully loaded, the barge will have the best carrying-capacity-to-draft ratio in the U.S. dredging industry.
The company is also planning for the construction of two new material scows along with the ATB. The project is expected to add more than 250 new jobs at the shipyard. Delivery is expected in the third quarter of 2014.