VT Halter Marine has started construction with a keel laying for the second Commitment-class liquefied natural gas (LNG)-powered, combination container, roll-on / roll-off (ConRo) ship for Crowley Maritime’s liner services group.

Crowley’s two Commitment-class ships are designed to serve the US-Puerto Rico trade lane.

Crowley technical services senior-vice president and general manager Todd Busch said: "The keel laying marks the ceremonial beginning of the construction and formation of the backbone of a ship.

"Today’s event symbolises how far we’ve come in delivering on our commitments to our customers in Puerto Rico.

"We are very excited to continue the construction process for these technically advanced ships."

The two vessels, named as El Coquí and Taíno respectively, are expected to replace Crowley’s fleet of towed triple-deck barges, operational since the early 1970s.

The 219.5m-long and 32.3m-wide vessels have been designed to maximise the carriage of 53ft, 102in-wide containers in order to provide better cubic cargo capacity.

With a deadweight capacity of 26,500 metric tonnes, the ships’ cargo capacity will be approximately 2,400TEUs in addition the space for nearly 400 vehicles in an enclosed roll-on / roll-off garage.

El Coquí is expected to be delivered in the second quarter of 2017, while the delivery of Taínoare is scheduled for fourth quarter of this year.

The vessels were designed by Wartsila Ship Design in collaboration with Crowley subsidiary Jensen Maritime.

Powered by LNG, the vessels will provide a 100% reduction in sulphur oxide (SOx) and particulate matter (PM), and a 92% reduction in nitrogen oxide (NOx).

Image: The keel laying of second vessel. Photo: courtesy of Crowley Maritime Corporation.