Unmanned surface vehicle

An unmanned surface vehicle, unmanned surface vessel or uncrewed surface vessel, colloquially called a drone boat, drone ship or sea drone, is a boat or ship that operates on the surface of the water without a crew. USVs operate with various levels of autonomy, from remote control to fully autonomous surface vehicles.

Regulatory environment

The regulatory environment for USV operations is changing rapidly as the technology develops and is more frequently deployed on commercial projects. The Maritime Autonomous Surface Ship UK Industry Conduct Principles and Code of Practice 2020 has been prepared by the UK Maritime Autonomous Systems Regulatory Working Group and published by Maritime UK through the Society of Maritime Industries. Organisations that contributed to the development of the MASS Code of Practice include The Maritime & Coastguard Agency, Atlas Elektronik UK Ltd, AutoNaut, Fugro, the UK Chamber of Shipping, UKHO, Trinity House, Nautical Institute, National Oceanography Centre, Dynautics Limited, SEA-KIT International, Sagar Defence Engineering and many more.
By the end of 2017, Sagar Defence Engineering became the first company in India to build and supply USV to a government organization.

Development

As early as in World War I Germany designed and used remote-controlled FL-boats to attack British warships. At the end of World War II, remote-controlled USVs were used by the US Navy for target drone and minesweeping applications. In the twenty-first century, advances in USV control systems and navigation technologies have resulted in USVs that an operator can control remotely from land or a nearby vessel: USVs that operate with partially autonomous control, and USVs that operate fully autonomously. Modern applications and research areas for USVs and ASVs include commercial shipping, environmental and climate monitoring, seafloor mapping, passenger ferries, robotic research, surveillance, inspection of bridges and other infrastructure, military, and naval operations.
On January 17, 2022, the Soleil succeeded in completing the first fully autonomous sea voyage by ship. Built by MHI, the demonstration was conducted in cooperation of Shin Nihonkai Ferry. The seven-hour, 240-kilometre voyage, from Shinmoji in Northern Kyushu to the Iyonada Sea, recorded a maximum speed of 26 knots.
In August 2022, the MV Mikage of the Mitsui O.S.K. Lines sailed 161-nautical miles over two days, from Tsuruga to Sakai, successfully completing the first crewless sea voyage to include docking of an autonomous coastal container ship, in a two-day trial.

USV autonomy platforms

A number of autonomy platforms tailored specifically for USV operations have been developed. Some are tied to specific vessels, while others are flexible and can be applied to different hull, mechanical, and electrical configurations.

Name	Vendor	Type	Deployed vessels	Vendor bespoke USVs	Conversion to USV / OEM	COLREGs
Typhoon	Satfinder	Commercial	2
ASView	L3Harris	Commercial	100+
Sense	MAHI	Commercial
MOOS	MIT	Open source
SM300	Sea Machines	Commercial	7
SDE	Sagar Defence Engineering Private Limited	Commercial	7
Voyager	Robosys Automation	Commercial	24

Computer-controlled and operated USVs

The design and build of uncrewed surface vessels is complex and challenging. Hundreds of decisions relating to mission goals, payload requirements, power budget, hull design, communication systems and propulsion control and management need to be analysed and implemented. Crewed vessel builders often rely on single-source suppliers for propulsion and instrumentation to help the crew control the vessel. In the case of an uncrewed vessel, the builder needs to replace elements of the human interface with a remote human interface.

Technical considerations

Uncrewed surface vessels vary in size from under 1 metre LOA to 20+ metres, with displacements ranging from a few kilograms to many tonnes, so propulsion systems cover a wide range of power levels, interfaces and technologies.
Interface types in order of size/power:

PWM-controlled Electronic Speed Controllers for simple electric motors
Serial bus, using ASCII-coded commands
Serial bus using binary protocols
Analogue interfaces found on many larger vessel
Proprietary CANbus protocols used by various engine manufacturers
Proprietary CANbus protocols used by manufacturers of generic engine controls

While many of these protocols carry demands to the propulsion, most of them do not bring back any status information. Feedback of achieved RPM may come from tacho pulses or from built-in sensors that generate CAN or serial data. Other sensors may be fitted, such as current sensing on electric motors, which can give an indication of power delivered. Safety is a critical concern, especially at high power levels, but even a small propeller can cause damage or injury and the control system needs to be designed with this in mind. This is particularly important in handover protocols for optionally manned boats.
A frequent challenge faced in the control of USVs is the achievement of a smooth response from full astern to full ahead. Crewed vessels usually have a detent behaviour, with a wide deadband around the stop position. To achieve accurate control of differential steering, the control system needs to compensate for this deadband. Internal combustion engines tend to drive through a gearbox, with an inevitable sudden change when the gearbox engages which the control system must take into account. Waterjets are the exception to this, as they adjust smoothly through the zero point. Electric drives often have a similar deadband built in, so again the control system needs to be designed to preserve this behaviour for a man on board, but smooth it out for automatic control, e.g., for low-speed manoeuvring and Dynamic Positioning.

Oceanography, hydrography and environmental monitoring

USVs are valuable in oceanography, as they are more maneuverable than moored or drifting weather buoys, but far cheaper than the equivalent weather ships and research vessels, and more flexible than commercial-ship contributions. USVs used in oceanographic research tend to be powered and propelled by renewable energy sources. For example, Wave gliders harness wave energy for primary propulsion, whereas Saildrones use wind. Other USVs harness solar energy to power electric motors. Renewable-powered and persistent, ocean-going USVs have solar cells to power their electronics. Renewable-powered USV persistence are typically measured in months.
As late as early 2022, USVs had been predominantly used for environmental monitoring and hydrographic survey and future uptake was projected to be likely to grow in monitoring and surveillance of very remote locations due to their potential for multidisciplinary use. Low operational cost has been a consistent driver for USV uptake when compared with crewed vessels. Other drivers for USV uptake have changed through time, including reducing risk to people, spatio-temporal efficiency, endurance, precision and accessing very shallow water.
Non-renewable-powered USVs are a powerful tool for use in commercial hydrographic survey. Using a small USV in parallel to traditional survey vessels as a 'force-multiplier' can double survey coverage and reduce time on-site. This method was used for a survey carried out in the Bering Sea, off Alaska; the ASV Global 'C-Worker 5' autonomous surface vehicle collected 2,275 nautical miles of survey, 44% of the project total. This was a first for the survey industry and resulted in a saving of 25 days at sea. In 2020, the British USV Maxlimer completed an uncrewed survey of of seafloor in the Atlantic Ocean west of the English Channel.

Environmental Research Vehicles

Saildrone

A saildrone is a type of uncrewed surface vehicle used primarily in oceans for data collection. Saildrones are wind and solar powered and carry a suite of science sensors and navigational instruments. They can follow a set of remotely prescribed waypoints. The saildrone was invented by Richard Jenkins, a British engineer, founder and CEO of Saildrone, Inc. Saildrones have been used by scientists and research organizations like the National Oceanic and Atmospheric Administration to survey the marine ecosystem, fisheries, and weather. In January 2019, a small fleet of saildrones was launched to attempt the first autonomous circumnavigation of Antarctica. One of the saildrones completed the mission, traveling over the seven month journey while collecting a detailed data set using onboard environmental monitoring instrumentation.
In August 2019, SD 1021 completed the fastest uncrewed Atlantic crossing sailing from Bermuda to the UK, and in October, it completed the return trip to become the first autonomous vehicle to cross the Atlantic in both directions. The University of Washington and the Saildrone company began a joint venture in 2019 called The Saildrone Pacific Sentinel Experiment, which positioned six saildrones along the west coast of the United States to gather atmospheric and ocean data.
Saildrone and NOAA deployed five modified hurricane-class vessels at key locations in the Atlantic Ocean prior to the June start of the 2021 hurricane season. In September, SD 1045 was in location to obtain video and data from inside Hurricane Sam. It was the first research vessel to ever venture into the middle of a major hurricane.
In June 2025 the Danish ministry of defence deployed four Saildrones in the Baltic Sea to monitor Russia's "shadow fleet" of embargo-breaking oil tankers, and potential threats from that state to underwater infrastructure.