This is the second commentary in a multipart series exploring ways to strengthen the U.S. Navy’s fleet. The first part is available here.

Recent events in the Middle East raise questions about how best to sustain finite naval power in strategically important waters. The U.S. Navy destroyer Carney fired missiles mere weeks into its deployment; the destroyer Thomas Hudner downed drones twice in eight days; and the destroyer Mason foiled a piracy attempt after which two ballistic missiles were fired toward it. And all this in a maritime theater that does not host America’s “top pacing challenge.”

Like these ships, guided-missile destroyers, or DDG, form the backbone of the U.S. surface force, which operates 73 of them and has plans to field at least 90. While they carry a large arsenal of vertically launched offensive and defensive weapons — as will the forthcoming Constellation-class frigates — onloading missiles takes time and precision. Once their magazines empty, ships must retreat to a safe port to refill while other units replace them — or not.

I have argued that the U.S. should pursue a collaborative shipbuilding approach with allies to increase the supply of forces and reduce pressure on the current fleet. But such a campaign would take years.

Meanwhile, this is precisely why Navy Secretary Carlos Del Toro — a former DDG commanding officer — has issued calls to prioritize concepts like reloading warships’ Vertical Launching System cells at sea to “increase forward, persistent combat power with the current force.”

“If we are able to rearm our warships’ vertical launch tubes at sea,” Secretary Del Toro argues, “we can stay ‘in the fight’ far longer. We won’t have to withdraw from combat for extended periods to rearm.”

Unlike underway replenishments — when ships resupply while traveling tethered — onloading missiles requires immovability. Consequently, aside from strategic, geographic, environmental and logistical factors, stillness becomes a critical prerequisite.

When loading ammunition pierside, the ship is tied to a fixed structure that keeps its direction steady and prevents movement from the lapping waves. The crane sits on land.

However, at sea, ships are vulnerable to the effects of wind, waves and current, which induce rolls and change the ship’s direction, or heading. While commercial technology called dynamic positioning, or DP, allows the crane ship to hover nearly motionless, DDGs lack such capability and are subjected to the powerful hydrodynamic effects of the crane ship’s thrusters.

Nevertheless, recent Vertical Launching System, or VLS, rearming experiments — including one aboard the DDG I commanded — demonstrate its promise. Additional doctrinal advances and equipment investments could help realize at-sea rearming’s operational potential even sooner.

First, refine engineering solutions to steady ships when transferring ordnance at sea. One option is to revive so-called Med Mooring techniques used in ports with tight slips (but less commonly employed by today’s U.S. Navy ships) where both the bow and stern are fixed to an anchor or buoy. This stabilizes the receiving ship’s heading by preventing it from swinging. Another includes lightering, in which the delivery and receiving ships compensate for motion by tying together without engines running, allowing both vessels to move or drift in harmony. Still another is to revisit sea-basing concepts where the DDG first moors to a larger ship — like a tender, expeditionary sea base or auxiliary (the basis for previous trials) — to mitigate the sea churn caused by the DP thrusters. Standard operating procedures and go/no-go criteria would guide commanding officers and ensure safety of personnel and equipment.

Second, identify deep-water harbors, protected anchorages and foreign ports in which to reload safely, and invest in low-cost mobile facility enablers — like those used in the 1940s — as an alternative to permanent infrastructure. These include floating pier-like pontoon platforms to secure ships during ordnance transfers, and fenders and separators for ship classes like DDGs whose bow flare and protruding sensors complicate side-by-side mooring.

Third, procure and pre-position commercially produced offshore support vessels. These ships — with geo-stabilized cranes and DP propulsors designed for oil platform resupply, wind turbine maintenance and more — are built by numerous Gulf Coast-based American firms and can be adapted for military rearming. Navy program experts explored this idea in 2020, and Navajo-class towing, salvage and rescue ships currently in production integrate some of these technologies.

Fourth, incorporate at-sea rearming hull, mechanical and electrical requirements into future platforms like DDG(X), and explore retrofitting them onto newer DDG-51s and frigates whose service lives extend for decades. Absent traditional ballast systems, adding DP thrusters or drop-down auxiliary power units could help DDGs minimize movements during these precise evolutions. A back-to-the-future return of foldable VLS “strike-down” cranes capable of handling modern missile cannisters during replenishments may make operational sense, too.

Fifth, ask allies for help. At least 11 allied nations employ a variant of the American-made MK 41 VLS. Many are home to thriving manufacturing industries capable of tackling these challenges. Collaborating on this capability would fit neatly into the Department of the Navy’s enduring priorities to strengthen maritime dominance and enhance strategic partnerships. Moreover, it would build collective operational resilience among likeminded navies and demonstrate that at their core, alliances are mutually beneficial.

The 2022 National Security Strategy declares: “A combat-credible military is the foundation of deterrence and America’s ability to prevail in conflict.” Reloading ships at sea will — excuse the pun — deliver.

Cmdr. Douglas Robb commanded the U.S. Navy’s guided-missile destroyer Spruance, and is currently a U.S. Navy fellow at the University of Oxford. The opinions expressed in this commentary are those of the author and do not reflect the views of the U.S. Defense Department, the Department of the Navy nor the U.S. government.

This is the second commentary in a multipart series exploring ways to strengthen the U.S. Navy’s fleet. The first part is available here.

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