NASSCO began building commercial cargo ships in 1959 , eventually including large cargo ships and Alaska class oil tankers . Its most famous commercial ship was the '' Exxon Valdez '' tanker , which completed construction at NASSCO in 1986 , and in 1989 returned to NASSCO for repairs after its accident and oil spill in Alaska . In December 2012 the company signed a contract to build two container ships powered by liquefied natural gas ( LNG ) . When completed they will be the largest LNG-powered ships of any kind in the world
oil spill
Exxon Valdez oil spill
National Steel and Shipbuilding Company