National Steel and Shipbuilding uses a traveller-mounted GMA gun to make vertical up butt and fillet welds on ship bulkheads. An oscillator mounts on a travel carriage that moves upward on an aluminum track attached to a steel rack. Solid-state speed controls make possible precise inches-per-minute travel settings. Overall welding time is 40 to 45 percent less than the time required to weld the same joint manually.