A quiet swarm over disputed waters: China's wave gliders take to the ocean
The experimental glider "Hai-Yao". The above-water and underwater parts are clearly visible.
Chinese science and industry have long been exploring the concept of unmanned wave gliders. Such vehicles are capable of long-term operation in the open sea and can perform a variety of tasks, from oceanography to naval patrols. According to Chinese industry publications, such platforms are capable of carrying search equipment and enhancing situational awareness. fleet.
On the pages of print
The topic of Chinese wave gliders has been regularly raised in the press in China and other countries in recent years. Most publications focus on the development and testing of specific prototypes and the assessment of their potential.
A recent issue of Naval and Merchant Ships, a magazine published by the China State Shipbuilding Corporation (CSSC), revisits this topic, this time from a military perspective. According to the article's authors, unmanned wave-driven systems offer a number of important features: the ability to conduct long-term patrols, transit between zones, and achieve high levels of autonomy due to the propulsion principle itself.
To operate effectively, the glider must carry modern equipment: optical, radar, and hydroacoustic, depending on the mission. The publication notes that the control system may include elements of artificial intelligence.
The authors of the article also consider practical applications. For example, they propose using similar technology in the South China Sea, where China has territorial disputes with several of its neighbors (with Vietnam, the Philippines, and Malaysia around the Spratly and Paracel Islands) and where the US Navy regularly patrols. The gliders could monitor foreign naval activity near disputed waters. In the future, deployment areas will be determined by the military-political situation and the needs of the PLA Navy.
Glider on the water
This article only addresses general issues related to the use of wave gliders; specific models and their characteristics are not discussed. Apparently, such issues are being worked on behind closed doors.
Wave principle
A wave glider is an unmanned vessel without its own propulsion system, using wave energy for propulsion. The classic design, developed abroad and adopted in China, is a semi-submersible double-hull: a flat-bottomed platform above the water carries control instruments, batteries, solar panels, and communications equipment, while an elongated underwater module, connected to it by a tether, is equipped with a set of transverse planes. Fully submersible versions also exist, discussed below.
The underwater module's automation monitors the wave conditions and adjusts the angle of attack of its surfaces. Vertical water vibrations are converted into horizontal thrust: the underwater section begins to move, pulling the surface platform along with it.
The main advantage of this design is its efficiency: wave energy is virtually free and not limited by fuel. The device produces virtually no noise and is compatible with a wide range of payloads.
The disadvantages are no less significant. The speed does not exceed a few knots, the vehicle loses power in calm weather, and maneuverability is limited. Some models are equipped with an auxiliary electric propeller for operation in calm weather, but this reduces endurance. For military use, this profile limits realistic missions to a narrow range: long-term stationary observation, hydroacoustic barriers, data relay from underwater vehicles, and weather reconnaissance for the navy. Active target pursuit, covert reconnaissance (the surface section always reveals the vehicle), or operation in poor weather are difficult or impossible. Vulnerability to capture or damage is a separate issue: the glider is slow and unable to evade attack. An additional practical limitation is biological fouling of the hull, which means that the real-world endurance of even the best models is measured in months.
Gliders are nevertheless considered a successful platform for surface and underwater surveillance equipment. The deployment of weapons is theoretically possible, but, as noted in the Naval and Merchant Ships publication, impractical.
In further developing gliders, Chinese developers are counting on AI and group deployment—even to the point of "swarming." It's worth noting here: for slow, wave-sensitive vehicles, a "swarm" makes more sense as a distributed sensor network (for example, a hydroacoustic barrier consisting of dozens of nodes) than as a maneuverable flock in the military sense.
Foreign context
Wave gliders are not a Chinese development. The lead belongs to the American company Liquid Robotics, whose Wave Glider SV2 entered service around 2009, and the more advanced SV3 in the mid-2010s. These vehicles are used by the US Navy, NOAA, and a number of commercial customers, collectively logging hundreds of thousands of nautical miles. The UK and Australia also developed their own programs. Therefore, Chinese projects are a catch-up, but an independent direction, rather than pioneering work.
Chinese development
The wave glider project was officially included in the state scientific and technical program "863" in 2014, at which time targeted funding was allocated for this area. By the early 2010s, two parallel developments had effectively emerged in China: the military-industrial and the academic. The press often conflate these projects, although they are structurally distinct.
Sea Ray (Hai-Yao) — Research Institute No. 710 (Yichang, Hubei Province), historically part of CSIC and, after the 2019 merger, part of the redesigned CSSC. It is a specialized military-industrial contractor. The Qingdao National Laboratory of Marine Science and Technology, with which the project is sometimes associated, acted only as a customer for joint civilian missions, not as a developer.
According to the Research Institute's official announcement No. 710 from September 2017, the Hai Yao 6000 model completed 94 days of comprehensive sea trials in the South China Sea, including operation in a typhoon zone. The device collected meteorological data and transmitted it to the operator. Following the trials, it was declared "ready for serial production," but there is no information available in open sources about the actual launch of serial production—it is primarily a pilot production at the Research Institute's own facilities.
"Hai Shao Bing" (Sea Sentry, 海哨兵) — a civilian academic project with no direct affiliation with CSSC. Its developer, the Ocean University of China (OUC, Qingdao), has developed its own line of wave gliders (including the Black Pearl series). The device is smaller and lighter than the Hai Yao and optimized for operation in stormy conditions; according to Chinese reports, it was used in the impact zones of typhoons Hato (2017), Bailu (2019), Lingling (2019), and Mitag (2019). For commercialization, the Qingdao Haizhou Technology (青岛海舟科技) company was established in Qingdao, mass-producing these climate monitoring platforms.
Thus, today in China there are actually two distinct lines of wave gliders, each with its own customers, different manufacturers, and varying degrees of transparency. The military-industrial line (Research Institute No. 710) is developing in a closed circuit, while the academic line (OUC / Qingdao Haizhou) is developing in a commercial and public sphere.
The CSSC is likely continuing to develop new vehicles for the armed forces. According to the author, these are most likely new platforms for hydroacoustic and other surveillance equipment.
A related class of gliders is also worth mentioning: underwater gliders. These are essentially miniature submarines with a similar principle of long-term autonomous operation (in Russian literature, the terms "underwater glider" and "underwater gliding vehicle" are also found). China has its own line of gliders in this area: the deep-sea glider "Haiyi" (Sea Wing, 海翼), which are technically hydrodynamic rather than wave-powered: they utilize buoyancy changes, but perform similar tasks of oceanographic and hydroacoustic reconnaissance.
The reaction of the United States and regional neighbors
The active deployment of Chinese unmanned naval systems—both surface (unmanned surface vehicles) and underwater (unmanned underwater vehicles)—is causing a noticeable reaction in the United States and countries in the region. It's important to distinguish between official statements and analytical assessments from the expert community—the two are not always the same.
US position. The Indo-Pacific Command and Pentagon analysts view Chinese oceanographic unmanned vehicles as a dual problem. First, collecting temperature, salinity, and current data directly improves the operating conditions of Chinese sonar systems—a classic task of hydrographic preparation of a theater of operations, undertaken by all navies worldwide. Second, a hypothetical threat to US underwater communications and fixed sonar networks in the Western Pacific is being discussed; there are no confirmed incidents involving Chinese vehicles in this area, but related concerns are regularly noted in the Pentagon's Annual Report to Congress on Military and Security Developments Involving the People's Republic of China. As an asymmetric response, the US is developing the Replicator initiative—the mass production of inexpensive, domestically produced unmanned platforms for saturating the waters.
There have been previous instances of mutual "fishing" of drones. In December 2016, a Chinese ship seized an American underwater glider deployed from the USNS Bowditch in the South China Sea (it was soon returned). Later publications also noted the opposite—the discovery and recovery of Chinese drones by military and civilian vessels from countries in the region.
Regional neighbors. The Philippines has detected Chinese unmanned vehicles (UAVs) in its exclusive economic zone (EEZ) and has declared its intention to disrupt their operations. Indonesia is the most prominent example: fishermen and the country's coast guard recovered Chinese-made Haiyi-class underwater gliders in December 2019 near Sulawesi Island, in December 2020 in the Selayar Strait, and in January 2023 near the Selayar and Natuna Islands. These discoveries fall along routes crucial for submarine passage from the South China Sea to the Indian Ocean through the Sunda, Lombok, and Makassar Straits; Jakarta has sent official notes to Beijing. Vietnam has expressed concern about the presence of Chinese UAVs near the Paracel Islands. Japan views the activity of Chinese UAVs near the Senkaku Islands as part of pressure in the "gray zone" and is expanding its own underwater robotic programs.
Legal context. The United Nations Convention on the Law of the Sea (UNCLOS) does not clearly define the status of unmanned marine vehicles. China insists that its civilian gliders are free to conduct scientific research in any waters, but simultaneously classifies similar US activities in its EEZ as exploration. The US and most regional states believe that unmanned vehicles without obvious naval affiliation lack sovereign immunity, and their operation in another state's EEZ without notification constitutes a violation of the coastal state's sovereign rights. Due to this legal uncertainty, practice outpaces norms: unidentified vehicles are increasingly being confiscated or studied on the spot.
Сonclusion
Over the past 10-15 years, Chinese scientific and defense organizations have developed a wave glider concept borrowed from American experience and brought it to practical use. Two parallel lines have emerged—the military-industrial (Research Institute No. 710 / CSSC) and the academic (China Ocean University / Qingdao Haizhou), which are often conflated in public publications. The publication of a review article in the CSSC journal does not prove the existence of a new generation of military-grade prototypes, but it does indicate continued industry interest in this topic. At the same time, international reaction is growing: China's unmanned vehicles are increasingly viewed by their neighbors and the United States as an element of their naval presence rather than a neutral scientific instrument—and this shifts the topic from a technical to a political and legal dimension.
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