General Dynamics' (NYSE:GD) NASSCO subsidiary announced Wednesday that it will be building two tankers for the Seabulk Tankers subsidiary of SEACOR Holdings (NYSE:CKH).

The tankers, 610-foot-long, 50,000-deadweight-ton, LNG-conversion-ready product carriers, will both have the capacity to carry 330,000 barrels of liquefied natural gas. Construction will begin late next year, with deliveries of the two vessels slatedĀ for Q2 2016, and Q1 2017, respectively.

In a statement, NASSCO noted that both tankers will follow the "ECO tanker design" developed by South Korea's Daewoo Shipbuilding & Marine Engineering. This design, says NASSCO, "offers improved fuel efficiency and incorporates the latest environmental protection features, including a Ballast Water Treatment System." These two tankers will bring to six the total number of ECO tankers being built by NASSCO, as the company received an order for four such tankers back in May from privately held American Petroleum Tankers.

Financial terms of today's announced construction contract, like that of the contract announced back in May, were not disclosed.