Harvey Gulf International Marine (HGIM) has received the OK from both the American Bureau of Shipping and Coast Guard on its design for a 4,000-cubic-meter LNG articulated tug/barge (ATB) unit construction drawing package. The design combines a 128'x42'x19', 5,100-hp tug and a 324'x64'x32'6" LNG barge with a draft of 16' and includes ship-to-ship transfer and shore side resupply transfers.
Working closely with its design partner Waller Marine and in conjunction with ABS and the Coast Guard, HGIM has developed the design package ahead of construction thereby minimizing the potential for delays and significant cost impacts to the project during construction. From the initial idea to its approval, it took 2.8 years, HGIM’s chairman and CEO Shane Guidry said in an email. “The next step is to start building one.”
Harvey Gulf has been out front in its development of LNG as a marine fuel, delivering the 310'x64'x25'6" Harvey Energy, the first U.S. vessel to use LNG as a marine fuel, in February 2015, and developing and operating the first LNG marine refueling terminal in the U.S. at Port Fourchon, La.
The new ATB design meets all domestic and international requirements of a gas carrier, including the existing regulatory requirements. “This is a bunkering ATB,” said Guidry. “It can bunker docks, vessels, rigs, etc.”
The design features four independent 999-cubic-meter type “C” cargo tanks, the ability to load and discharge at a rate of 600 cubic meters per hour ,and transit speed in excess of 10 knots. The design incorporates a robust fire and safety system concept for both components of the ATB and the independent ability of the vessels to manage situations as they arise.
Harvey Gulf said that working together with Wärtsilä, the cargo systems integrator on the design, supply, and integration onboard the vessel, assures both functionality and confidence in the operability of the system.
Another key component of the ATB design is the use of a sub-cooler for boil off gas (BOG) management, working in conjunction with Air Liquide using its Turbo-Brayton technology (TB 350) as a means to condition the cargo as necessary to manage BOG.