The USS Zumwalt, the lead ship of the U.S. Navy’s Zumwalt-class destroyers, has returned to sea trials after three years following a major modernisation.

The upgrade replaces the ship’s expensive naval guns with missile tubes for the Conventional Prompt Strike hypersonic weapon.

The destroyer had been docked since summer 2023 while the Navy removed its two 155mm Advanced Gun Systems, which were considered too costly to operate.

Each shell for these guns cost about $1 million, compared with $3,000–$4,000 for standard NATO artillery rounds.

The redesign also freed up space beneath the former gun mounts and allows room for future upgrades.

Originally designed for stealthy support of near-shore operations, the Zumwalt is now focused on long-range strike missions in open waters.

The three-ship class limits its overall scale, but the addition of hypersonic weapons gives it a new role.

Named after former Chief of Naval Operations Admiral Elmo Zumwalt, the class was initially intended to include over 30 ships.

Analysts have said that unrealistic cost estimates, immature technologies, and integration challenges led to the reduction to just three ships.

Cost overruns were large enough to trigger the Nunn-McCurdy Act, which mandates review when defence projects exceed budget projections.

The Zumwalt-class is known for its unique tumblehome hull, designed to reduce radar detection, and the extensive use of composite materials.

Automation reduces crew size, and the ships generate significant electricity, intended to support future advanced weapons.

The Advanced Gun System was meant to support land forces during amphibious operations.

However, the guns were incompatible with standard 155mm artillery shells, making them effectively unusable.

Reference: 19fortyfive