SHIPBUILDING: Rivetless Ship

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Into the waters of the East Pascagoula River last week slid the 492-foot, 8,900-ton cargo ship Exchequer - first ship launched from Ingalls Shipbuilding Corp.'s brand-new ways at Pascagoula, Miss. Lat est addition to the Maritime Commission's new U. S. merchant marine (500 ships in ten years), the $2,600,000 cargopassenger carrier held more than passing interest for U. S. shipbuilders. She was the largest all-welded general cargo ship ever built in the U. S.

Although Germany built her famed 10,000-ton pocket battleships without using a single rivet, she kept secret her welding methods and their results. Until last week the only large all-welded U. S.-built ships were tankers. When the Exchequer steams away from her fitting-out dock, she will hold her first trial run over the U. S. Navy speed course off Guantanamo, Cuba. Reason: Navy and Maritime Commission officials are anxious to find out whether her

STEELMAN INGALLS In his yard, only a hissing.

smooth, seamless hull (in contrast to the overlapping plate hull of a riveted ship) will boost her scheduled 16½knot speed.

Ingalls' officials were most interested last week, however, in the fact that they had completed their first big ocean-going ship and made a profit on it. Moreover, they had done the job so cheaply that they expected to turn back money to the Maritime Commission, which limits profits to 10% on its contracts. What helped Ingalls to this astonishing record was the fact that it was streamlined to do the job.

A $500,000 shipyard, built fresh from the ground up, it would have needed ten times as much capital to build riveted ships and equip a plant to fabricate its own steel, which comes from its parent company, Ingalls Iron Works Co., at Birmingham, Ala.

But Ingalls will have to build many more ships to make good its boast that its new methods will revolutionize U. S. shipbuilding. In contrast with the machine-gun clamor of most shipyards, Pascagoula's noises are a sibilant hiss. Biggest plug for welding is the fact that one welder can do the job of a four-man riveting team-a big saving in labor (40% of shipyard cost). Ingalls welds complete stern assemblies, bow sections, etc. up to 75 tons on platforms in the yard, swings them into place with big gantry cranes. It reverses old-line shipbuilding techniques by laying decks on shored-up timbers, then attaching framework (ribs, etc.), instead of building from the keel up. It estimates a 16% saving in steel over a riveted ship of the Exchequer's capacity, which would have needed 1,250,000 rivets as well as overlapping plates. And it claims a maintenance triumph because welded ships can be repaired by welding too. (Cost of repairing riveted ships: $1.50 per rivet.)