Commitment (C) Class LNG-Powered ConRo Ships, United States of America
The Commitment (C) Class liquefied natural gas (LNG) powered combination container Roll-On/Roll-Off (ConRo) ships are being built by VT Halter Marine for Crowley Maritime Corporation's liner services group.
Crowley signed a contract with VT Halter Marine, a subsidiary of VT Systems, for two vessels of the new Commitment (C) Class in November 2013. The total value of the contract is estimated to be $350m.
The two C-Class ships will be named El Coquí and Taíno respectively. Construction of the first vessel of this category began in October 2014, with the first steel cutting ceremony at VT Halter Marine shipyard in Pascagoula, Mississippi. The first and second vessels are scheduled to be delivered to their owner in the second and fourth quarter of 2017, respectively.
The ConRo vessels will operate under the Jones Act trade and will transport containers and vehicles between the US and Puerto Rico.
The Commitment Class, Jones Act ships will replace Crowley's fleet of towed triple-deck barges, operational since the early 1970s. New ConRo vessels will be fitted to offer world class performance and optimum safety, reducing transit times and setting new standards of environment-friendly shipping.
Design of the Commitment Class ConRo Ship
The facility will provide for development of various small and remote offshore fields, which have not been tapped so far for their uneconomical propositions.
The Commitment Class ships have been designed by Wartsila Ship Design, in collaboration with Seattle-based naval architecture and marine engineering firm Jensen Maritime, a subsidiary of Crowley. Jensen will also manage and supervise the construction activities at the shipyard.
Double-hulled ConRo ships will be designed to carry 2,400 TEUs (20ft equivalent units) with a standard length of 20ft to 53ft and width of 102in. The vessels will also offer enough space to hold up to 300 refrigerated containers. They will also have extra space to accommodate 400 cars and larger vehicles in an enclosed, well ventilated and weather insulated spacious Ro/Ro garage.
The Commitment Class ships will have an overall length of 219.5m and beam of 32.2m. The depth and draft of the vessel will be 18m and 10m respectively and the deadweight will be approximately 26,500t.
The vessels will be highly energy-efficient and are expected to receive the CLEAN notation, as well as the Green Passport issued by Det Norske Veritas (DNV) classification society. Commitment (C) Class ships were assigned the DNV class notation and classified as 1A1 general cargo carrier, container, Ro/Ro, Nauticus (new building), gas fuelled, drawn, ground and polished (DG-P) BIS, TMON, BWM-T, E0, NAUT-OC, CLEAN.
Engine and propulsion
The main propulsion and auxiliary engines of the C Class vessels will be powered by LNG. The use of LNG will eliminate sulphur oxide (SOx) and particulate matter (PM) emissions. It will also bring down nitrogen oxide (NOx) and carbon dioxide emissions by 92% and 38%, respectively.
Dual-fuel vessels will use LNG as primary fuel and can also operate on traditional ultra-low sulphur diesel oil. The propulsion system allows the vessels to sail at a maximum speed of 22kt.