Moving a 694' floating drydock from land into the Mobile River required a nine-day dock build, roughly 1,500 crane mats, and little room to spare between two massive steel structures.
Austal USA, Mobile, Ala., has launched AFDM 15, the first Auxiliary Floating Dry Dock Medium built for the U.S. Navy in more than 40 years. Austal said the approximately 12,000-ton structure is the largest vessel launched into the Mobile River in the company’s 26-year history.
The 157'-wide drydock has an 18,000-long-ton lifting capacity and more than 90,000 square feet of clear working deck. It is designed to accommodate Navy destroyers and cruisers for maintenance and repair.
AFDM 15 was assembled by Austal at Alabama Shipyard, Mobile, Ala., before being moved from the transfer bulkhead onto the shipyard’s Dry Dock Alabama. Preparing the drydock to receive the vessel took nine days as crews positioned crane mats and dock blocks according to the approved docking plan.
“Receiving AFDM 15 into our drydock and supporting its launch into the Mobile River was a highly coordinated operation that required months of planning, engineering, and collaboration,” said Alabama Shipyard CEO Greg Wagner.
Berard Transportation, New Iberia, La., then used self-propelled modular transporters to move AFDM 15 from land onto the drydock. Austal said crews used approximately 1,500 crane mats to create an elevated travel path 4' above the drydock’s caisson deck.
Clearance was tight between the walls of AFDM 15 and the wing walls of Dry Dock Alabama, adding another complication to a transfer that involved Austal teams, Alabama Shipyard, Berard, tug operators, river pilots, and other vendors. Austal said scheduling also had to account for the availability of each company, facility, and piece of equipment involved.
Once the transfer was complete, Dry Dock Alabama returned to its berth and was lowered in stages. Alabama Shipyard paused the operation between stages so Austal could perform watertight-integrity checks before the drydock was lowered further.
Mobile Harbor pilots and tug crews then assisted as AFDM 15 floated clear of the drydock and entered the Mobile River.
“The entire evolution required extensive planning, precise execution, and coordination among Alabama Shipyard, Austal USA, Berard Transportation, and the Mobile Harbor pilots and tug crews,” Wagner said.
Although AFDM 15 is the largest vessel launch Austal has coordinated, the company said the overall process resembled the launches of 36 other Navy vessels it has completed during the past 14 years.
Work remaining before delivery includes crane installation, generator light-off, builder’s trials, and acceptance trials. Austal expects to deliver AFDM 15 to the Navy in the first quarter of 2027.
