After its long service life, on February 20, Electric Boat’s Graving Dock 3 (GD3) pontoon left Electric Boat and traveled up the Thames River to its new home at Mohawk Northeast, Inc. in Groton. In 1978, the pontoon was certified for launching Ohio-class submarines. The pontoon is a 550’ x 105’ steel box weighing 5,000 long tons that was raised and lowered within GD3. When raised, a submarine can be rolled onto the pontoon deck and lowered into GD3 in preparation for float-off.
Since its certification, EB’s pontoon launched 18 Ohio, three Seawolf and 14 Virginia-class submarines. One Los Angeles-class boat, Jacksonville (SSN 699), was launched using the pontoon as a test prior to the launch of SSBN/GN 726, Ohio. In addition, several boats undergoing maintenance and modernization were dry-docked in GD3 including USS Virginia (SSN 774) and NR-1, which were dry-docked in GD3 simultaneously in May of 2007; USS Dallas (SSN 700), which was dry-docked in GD3 March 2007 and USS Memphis (SSN 691), which was dry-docked in GD3 in January 2007.
After SSN 799, Idaho, left GD3 in December 2024, the pontoon was de-certified and preparations began to ready its removal.
“This pontoon outhaul was truly a team sport,” said Pete DiNapoli, senior manager of Ships Management. “This required support from Docking Operations, Facilities, Engineering, Naval Architects, Program Office, Operations, Risk Assessment Engineering, Planning, Safety, Environmental, EBFD, Transportation, Optical Tooling, EB Security, Temporary Services, Tug Operators, Mohawk Northeast and Ships Management, demonstrating unity of effort across Electric Boat.”
At a high level, the outhaul work included removing the pontoon’s bearings, making it watertight, which took the most time and effort, and adding bumpers on the dock and the pontoon to move it safely within GD3 as the team was working with inches of clearance. Since Electric Boat had never removed a pontoon before, the team conducted a series of table-top exercises and a dry run to ensure success.
A new pontoon is being constructed at Bollinger Shipyard in Louisiana and will be installed in Graving Dock 3 this summer.
