The world’s first articulated tug barge (ATB) designed for LNG bunkering and coastwise shipments has been launched at Pascagoula, Mississippi, writes David Tinsley. The ATB combination, which comprises a 4,000m3-capacity tank barge and a dedicated, 39m push tug, will be handed over by VT Halter Marine in Q1 2020.
Contractual owner Quality LNG Transport (Q-LNG) has entered into a 15-year agreement with Shell Trading (US) to deploy the ATB to conduct LNG deliveries along the southeast US eastern seaboard and Gulf of Mexico (GoM). One regular recipient will be Carnival Cruise Line, which has two dual-fuel LNG cruise ships under build in Germany. The ATB concept is well proven in the US coastwise and inland waterway trade, having become a vital element in petroleum and chemical product distribution, but has never before been applied to LNG transportation.
The barge has a notched stern and coupling system for the tug. The articulated or hinged connection between the tug and barge allows independent movement between the two vessels, for better performance in rougher sea conditions and improved manoeuvrability, speed and efficiency. The tug, Q-Ocean Service, has been specified with two GE six-cylinder L250MC main engines and a twin Z-drive configuration based on Wärtsilä nozzled, steerable thrusters. The diesels generate 3,800kW in total and are EPA Tier 4-compliant without the need for additional exhaust treatment measures.
The barge, named Q-LNG 4000, is designed to meet the requirements of the International Gas Carrier (IGC) Code, and is laid out with four 1,000m3-capacity, IMO type C LNG tanks within a hull envelope of 98.7m overall length, 19.5m beam and 9.8m depth.
In addition to performing direct ship-to-ship transfers, the ABS-classed barge will also be used for ship-to-shore unloading to small-scale marine distribution infrastructure in the GoM and abroad. While propulsive force is exerted by the tug, the barge is not entirely ‘dumb’, having been fitted with a Wärtsilä bow thruster to assist in manoeuvring.
Based at Port Canaveral in Florida, Q-LNG Transport will draw loads from the Elba Island LNG terminal in Savannah, Georgia. It is understood that Q-LNG has a letter of intent with VT Halter for a second, significantly larger LNG ATB of up to 8,000m3 capacity.