Local Woman Christens Navy Concrete Barge Mrs. D. M. Callis of Coronado, wife of the naval architect responsible for obtaining the initial agreement for construction of the concrete barges at National City, christened the fifth of these giant fuel-carrying barges, at ceremonies at the Ship Construc tors yards in National City at 10:30 Tuesday morning. The vessel, of 14,000 tons displace ment, will be turned over to the Navy as part of its tanker fleet. Two other yards, in Savannah, Ga., and Houston, Texas, which received contracts about the same time as the National City firm, have yet to launch their first craft and are subjects of a senate committee investigation. Launchings have been occuring here periodically since last October 18th. The barges are not self-propelled, and must be towed by powerful tugs. Use of concrete saves approximately 40 per cent of the steel which would ordinarily be required in construction.