March 31, 2025: The southeast Asian city-state of Singapore is responsible for security of the 223 kilometers long and 19 kilometers wide Singapore Strait that connects the Strait of Malacca and the South China Sea. Over a thousand ships a day traverse this seaway. Until recently security consisted of shore based sensors and offshore patrol ships. Recently Singapore added some Maritime Security Unmanned Surface Vessels or MARSEC naval drones. These 30-ton drones are 16.9 meters long and 5.2 meters wide. Top speed is nearly 50 kilometers an hour and endurance is up to 40 hours at sea.

A two man team ashore or in a nearby vessel controls the MARSEC drones. They are equipped to identify a ship by reading its mandatory transponder and track its movement through Singapore controlled waters. The drone’s electronics handles avoiding obstacles. Additional equipment includes a strobe light, siren, an LRAD/ Long Range Acoustics Device for interrogating people on small boats that lack a radio, and a 12.7mm machine-guns that includes a non-lethal laser dazzler to temporarily blind suspicious subjects. MARSEC has been successful at increasing security at a lower cost and using less manpower.

MARSEC is not the first such drone. For years America and China have been competing to develop more drones similar to MARSEC. So far China has produced the Zhu Hai Yun, a 2,000-ton ship that carries up to fifty drone submarines, surface and airborne vehicles. Zhu Hai Yun is operated remotely to get it out to the high seas, where the ship operates autonomously to carry out a variety of missions it is capable of. China is depending on its Artificial Intelligence/AI software to effectively carry out its mission and then signal that it is returning.

The U.S. Navy has similar but smaller 145-ton unmanned surface ships that do not carry and operate other drones, but can stay at sea for up to sixty days carrying out Anti-Submarine Warfare/ASW missions. The navy has also developed larger autonomous cargo ships to move supplies long distances. Smaller armed and unarmed autonomous vessels have been in service for decades to patrol ports and coastal areas. China believes it has a lead in AI control software and the Zhu Hai Yun is an effort to test that. The Americans are depending on less ambitious technologies that have produced impressive results so far, and a new Orca autonomous submarine takes those proven concepts further than ever before.

A month before China presented the Zhu Hai Yun, the Americans received the first of 24 Orca 80-ton Extra-Large drone/XLUUV drones that can carry and deploy a variety of naval mines and evade enemy detection due to their small size.

Orca was the U.S. Navy solution to the difficulties with deploying offensive mobile naval mines and a robotic submarine in enemy controlled waters, like the South China Sea. Orca could even operate as an offensive weapon against Chinese submarines seeking to block access to the South China Sea and Taiwan. China is considered the major submarine threat in the Pacific and the South China Sea is seen as a major future battleground.

Currently China has about 55 diesel-electric subs of recent design in service versus 42 operated by Japan and South Korea, each with 21. Malaysia and Indonesia each have two and Australia has six. The United States has about 30 nuclear attack subs in the Pacific. The anti-China coalition also has a large array of surface and aerial ASW forces.

To even the odds China has built a network of underwater sensors in the South China Sea that is complemented by ASW aircraft and surface ships. South Korea and Japan have similar technology monitoring their coastal waters. The only nation capable of blocking Chinese subs from moving out of the South China Sea is the United States, which has underwater sensors and a large fleet of ASW aircraft. The problem is defeating the Chinese diesel-electric submarine force. China has been trying to build effective SSNs for decades and that is still a work-in-progress. Chinese non-nuclear subs are another matter and they have become world-class.

The U.S. Navy believes robotic subs carrying mobile mines would be an effective new ASW asset because the U.S. is already developing some of the new ASW technology needed for this. This includes underwater drones and mobile mines. Over a decade ago the navy adopted civilian underwater drones used for monitoring the oceans, and has been using them to do that as well as collect data useful for wartime submarine operations. With a growing number of civilian and military customers, American drone developers and manufacturers have been coming up with new ocean research drones that also have military applications. The latest example of this is the new class of XLUUV with the ability to go deeper, carry a cargo bay for other research gear to be stored and deployed from, and operate autonomously for up to six months. The first of these XLUUV was the Echo Voyager, which Boeing developed from a research project and had the first one ready for testing in 2016. The tests were successful and have involved more complex and completely autonomous operations.

In 2019 the navy ordered four militarized Orca versions of the Echo Voyager for $11 million each. Both models are diesel-electric powered autonomous subs that are 16 meters long with a payload compartment 9.1 meters long and 2.6 meters in diameter, and is located within the pressure hull. Propulsion is by battery powered electric motors and diesel generators to recharge the batteries when on or near the surface. This XLUUV has no topside sail and can stay underwater for days at a time because there is no crew on board to sustain. While submerged these drones can move at 14 kilometers an hour and have sufficient generator fuel to travel 10,500 kilometers. The main difference between Echo Voyager and Orca is that Echo Voyager is built to dive to extreme 3,400 meter depths. Endurance is over 60 days. Orca does without that but adds additional passive sensors and signal processing computers to detect other submarines or surface ships. There is also an underwater communications system for arming the dozen Hammerhead mobile mines Orca is designed to carry and place on the ocean floor in areas like the South China Sea. These Hammerhead bottom mines carry a Mk 54 lightweight torpedo, which is normally carried by ASW helicopters and aircraft. Mk 54 has a range of ten kilometers and a guidance system that is regularly updated. Hammerhead is being used in a similar fashion to a larger version of this used during the Cold War that deployed a larger Mk 48 torpedo. Hammerhead is an encapsulated system equipped with passive sensors to detect and identify submarines and surface ships and attack specific types of targets, like diesel-electric subs larger than Orca.

The first Orca was delivered on time in 2022 and entered service in 2024. The navy plans to buy as many as 24 Orcas and use them for a variety of tasks while trying to avoid Chinese efforts to accidentally or deliberately capture one.