Mobilizing on September 27, 2024, Phoenix showcased its innovation in Underwater Ship Husbandry through the use of highly trained personnel and specialized equipment. After the removal of fairing plates and fairwaters from all four shafts, divers welded rigging pad eyes onto the ship’s hull to facilitate the installation of custom-designed stern tube cofferdams. These cofferdams-measuring up to 13 feet long, 12.5 feet wide, and 11 feet tall, and weighing as much as 8,000 lbs.-were engineered by Phoenix to form a dry seal while allowing shaft rotation during the flange inspections.
In addition to the stern tube cofferdams, interchangeable intermediate strut habitat cofferdams were also deployed. Divers installed the cofferdams over the Rotating Coupling Covers (RCCs), which were then drained to create a dry working environment. RCCS were removed and recovered to the pier for refurbishment by NNSY personnel.
Phoenix Level II NDT inspectors performed comprehensive evaluations of all shafting, flanges, bolts, and nuts using the company’s Dry and Dry Chamber methods: Liquid Penetrant Testing; Magnetic Particle Testing; and Visual Testing.
Following satisfactory inspection results, all components were cleaned using bristle blasters, painted, and reinstalled with preservatives.
In total, the Phoenix team logged 3,660 hours of bottom time and completed 187 linear feet of welds to support this essential inspection and maintenance effort.
