US Marines train in Japan with ALPV Autonomous Low-Profile Vessel based on narco submarine designs for stealth operations.

On April 23, 2025, the Marine Corps Installations Pacific (MCIPAC) reported that on April 9, the 31st Marine Expeditionary Unit’s Combat Logistics Battalion conducted training at the Kin Red Training Area in Okinawa, Japan. The training involved using an Autonomous Low-Profile Vessel (ALPV) to transfer cargo to a Joint Light Tactical Vehicle (JLTV). The unit, the only continuously forward-deployed Marine Expeditionary Unit, is responsible for conducting regular training activities to prepare for operations in the Indo-Pacific region, with an emphasis on logistics under maritime conditions.
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The Autonomous Low-Profile Vessel (ALPV), developed by Leidos, is a semi-submersible unmanned surface vessel designed for logistics support in maritime environments where visual, radar, and infrared detection are likely. (Picture source: USMC)

The Autonomous Low-Profile Vessel (ALPV), developed by Leidos and also referred to as the Sea Specter, is a semi-submersible unmanned surface vessel designed for logistics support in maritime environments where visual, radar, and infrared detection are likely. It is capable of transporting up to five tons of cargo over a distance of up to 2,000 nautical miles. Its low visual profile and semi-submersible form are derived from vessel concepts associated with narcotics smuggling operations, specifically drug-running semi-submersibles. The Marine Corps identified this design as useful for logistics support in denied or contested maritime zones, particularly in scenarios involving peer adversaries. The platform was introduced under the Pentagon’s Rapid Defense Experimentation Reserve (RDER) initiative and has since been evaluated by the Marine Corps Warfighting Laboratory.

The Autonomous Low-Profile Vessel (ALPV), also referred to as the Sea Specter, was developed by the DLBA division of Gibbs & Cox, a Leidos subsidiary. The design effort began in July 2022 with the objective of producing a low-profile, unmanned vessel capable of transporting a five-ton payload for a minimum range of 1,852 kilometers at a cruising speed of 14.8 km/h in Sea State 3, with an objective speed of 18.5 km/h under the same conditions. The vessel was required to have no onboard personnel and a maximum freeboard of 0.61 meters to reduce visibility. Initial autonomy was based on remote control and waypoint navigation, with provisions for enhanced autonomous capability in the future. The prototype construction was carried out at Weaver Boat Works in Deal, Maryland, beginning in November 2022 and completed by March 2023. Land-based testing of the control system preceded the vessel’s launch into Rockhold Creek, off the Chesapeake Bay, on April 17, 2023, 39 weeks after the contract to finalize the vessel’s requirements had been signed.

The ALPV measures 19.75 meters in overall length, has a beam of 2.41 meters, and a full-load draft of 1.47 meters. It has an operational range of 4,074 kilometers at 14.8 km/h and features a payload compartment measuring 8.84 meters in length, 1.22 meters in width, and 1.22 meters in height, with a payload capacity ranging from 2,000 to 4,627 kilograms. The vessel is powered by a single 230-horsepower Cummins diesel engine, with the propeller housed in a protective shroud. The ALPV’s tactical diameter at speed is limited to two boat lengths. It is capable of maneuvering directly to a dock without external assistance, although a tow vessel was used alongside during initial testing for safety purposes. At operating displacement, the vessel maintains less than 0.61 meters of freeboard, contributing to low visual detection. Its configuration was influenced by the profile and operational characteristics of narco-submarines. Gibbs & Cox delivered two prototype vessels within one year of the contract award and is currently developing a production model designed for mass manufacturing. The design allows for ballast modification to adjust payload or range, enabling the platform to meet different mission requirements, including those relevant to the Indo-Pacific region.

Based on the design of narco-submarines, the ALPV possesses a payload compartment measuring 8.84 meters in length, 1.22 meters in width, and 1.22 meters in height, with a payload capacity ranging from 2,000 to 4,627 kilograms. (Picture source: Leidos)

The vessel’s operational testing began in 2023. Two ALPV prototypes were delivered and used in Project Convergence Capstone 4, a joint and multinational exercise hosted by the U.S. Army. One test involved the remote operation of the vessel off the coast of California by a Marine located in Japan using proliferated low-Earth orbit communications. The vessel was also tested for shipboard loading and offloading using stern landing vessels and Spearhead-class expeditionary fast transport ships. These exercises assessed the vessel’s role in supporting the Navy/Marine Corps Expeditionary Ship Interdiction System (NMESIS), a system based on two Naval Strike Missiles mounted on a modified Joint Light Tactical Vehicle. The ALPV is able to transport a reload of two missiles for the NMESIS launcher.

In 2025, three Marine Corps logistics units, Combat Logistics Battalion 31, Combat Logistics Battalion 8 (based at Camp Lejeune), and 12th Littoral Logistics Battalion, conducted operational training with the ALPV. The 12th Littoral Logistics Battalion, part of the 12th Marine Littoral Regiment, emphasized the system’s role in supporting Stand-in Forces and logistics in contested environments. Training included both classroom instruction and hands-on exercises involving the mission planning interface and direct line-of-sight control systems. These activities occurred at Camp Hansen, Okinawa. Marines were also trained in port coordination, safety boat integration, and vessel mooring procedures. Cpl. Gilbert Elliott, a heavy equipment mechanic, described his involvement in both San Diego and Okinawa exercises, citing the development of procedural knowledge and the instruction of other Marines in tasks such as vessel tie-off and pre- and post-operation checks.

In addition to vessel operation, Marines assigned to the 12th LLB undertook daily swim training and prepared for participation in a six-week Maritime Operator Course conducted by the Expeditionary Operations Training Group. This training is intended to qualify Marines to crew Combat Rubber Reconnaissance Craft (CRRC) used for ALPV offloading in remote environments. According to unit personnel, the objective is to increase operational independence and support logistics missions where standard supply lines are impractical or compromised. The ALPV is also expected to be transferred to III Marine Expeditionary Force (III MEF) for further evaluation in the second half of 2025.

At operating displacement, the Autonomous Low-Profile Vessel (ALPV) maintains less than 0.61 meters of freeboard, contributing to low visual detection. (Picture source: Leidos)

The Marine Corps’ interest in the ALPV stems from its utility in maintaining logistics chains under threat conditions, especially within regions covered by adversary air and missile systems. The system has been described by Marine Corps Warfighting Laboratory representatives as “risk-worthy,” meaning it is suitable for tasks where manned platforms would face higher risk. Brig. Gen. Simon Doran stated that the system provides one response to the issue of sustaining operations inside a weapons engagement zone. The Marine Corps continues to evaluate how such platforms might be incorporated into ongoing operations without requiring constant monitoring from manned chase vessels, a current operational limitation being addressed in test plans. Doran also pointed to the need for modular and open-architecture systems to accommodate rapid technological changes and reduce training burdens associated with proprietary interfaces.

The ALPV was developed with reference to narco-submarines, semi-submersible and sometimes fully submersible vessels designed and used by drug traffickers in Latin America since at least the 1980s. These vessels, often constructed from fiberglass or steel, typically carry several tons of cargo and have proven capable of transoceanic travel. Some have been found equipped with satellite navigation and long-range radio communication systems. Narco-submarines are built in concealed shipyards, primarily in the jungles of Colombia, and are designed to minimize detection by radar, sonar, visual, and infrared systems. Several seizures over the past two decades have involved vessels with load capacities ranging from 4 to over 10 tons and capable of speeds around 11 km/h. While some are designed for one-time use, others include corrosion-prevention features for longer service life.

ALPVs and narco-submarines share several design and operational features that provide advantages in their respective contexts. Both utilize low profiles and semi-submersible construction to reduce observability across multiple detection spectrums. They rely on long-range navigation capabilities and low wake signatures to avoid detection during transit. Their hulls, often constructed from composite materials such as fiberglass, offer resistance to radar and sonar tracking. Both vessel types are built to function over extended distances and in environments where interception by opposing forces is a risk. Additionally, neither vessel type requires onboard personnel to function, allowing for the performance of missions where human presence would otherwise pose a liability. These shared attributes illustrate how design principles developed for illicit maritime transport have been adapted into platforms suitable for logistics support under military operational constraints.

Also referred to as the Sea Specter, the ALPV was also tested for shipboard loading and offloading using stern landing vessels and Spearhead-class expeditionary fast transport ships. (Picture source: USMC)