Advantages of Aluminum Parts in Shipbuilding

Dry cargo ships have been affected by new design trends that emphasize a need for lower topside weight. Heavier cargo handling gear and related machinery, and more narrow, hydrodynamically contoured, high-speed hulls have increased stability problems. Thus, weight saving is required to permit more efficient hull designs. Approximately 100 tons of welded 5086 plate and shapes 0.25 to 0.75 in. thick was used in the midship structures in each of ten ships built recently. Aluminum structures normally weigh only 40% as much as steel structures, using construction details similar to steel practice (welded plate and stiffeners bracketed at the decks). In some instances, additional weight is saved by application of special extrusions.

Crew boats are normally of hard-chine, planing-hull type, using developable surfaces in the hull form. This results in an efficient hull that is economical to fabricate. The builder also benefits from the lighter weight of the material being lifted into place, since fewer workers and pieces of hoisting equipment are required. One builder of personnel boats has shown that a 50-ft aluminum hull requires a fabrication time 33% less that for steel.

Aluminum is a popular choice for parts, thanks to its light weight and strength. But while it offers great versatility, its many uses can make your choice of protective coatings difficult. Tufram and Nedox engineered coatings are appropriate for a wide range of applications involving aluminum parts. Both coatings have characteristics that make them desirable for certain requirements, and we can modify each one to achieve special performance needs. Be sure to work with us early in the selection process to help you determine the best option for your aluminum parts.

Aircraft Carriers. Aluminum applications totaled over 1750 tons on the carrier "Enterprise" (CVA-65) completed in 1961. The largest single item was the four deck-edge elevators. The first such elevator platforms, employing welded 6061-T6 members in a tubular-truss structure, had been installed on the carrier "Shangri-La" (CVA-38). Later, alloy 5154-H36 was used for the welded elevators on CVA-61. Alloy and welding developments led to application of alloy 5456 plate and extrusions in the elevators on the "Enterprise". These were designed with an open grillwork structure; the deep girders were fabricated from 3/4 to 2 in. thick. The 52 by 85-ft structures weighted 105 tons each, 35 tons less than similar steel units. Reduced inertia, during operation between the flight and hangar decks, permitted reductions in operating machinery. The "America" (CVA-66), completed in 1965, employs elevators of stiffened-plate configuration, using high-strength steels; they weighed 115 tons each. A similar design but employing alloy 5456 resulted in aluminum being specified for the elevators on carrier CVA-67, now under construction, at a weight reduction of 15 tons each. Other uses included the items of equipment mentioned for destroyers, along with radar masts, superstructure, cooling panels in the flight deck, and comparable structures.