On Monday, October 27, 2025, the Swedish Defence Materiel Administration (FMV, Försvarets materielverk) of the Ministry of Defence of the Kingdom of Sweden announced the completion of sea trials of the Mariner autonomous unmanned surface vessel, developed by the Norwegian company Maritime Robotics. The vessel has been given the name Ran, in honor of the goddess of the sea depths in Norse mythology.
Photos: FMV
The two-week tests were recently conducted in the Hårsfjärden fjord area, near the Berga naval base in Haninge Municipality, Stockholm County. During the trials, the software, sailing range, maneuverability, and emergency stop function were tested, among other things.
“We have purchased a small boat — a concept demonstrator — with which we can conduct tests. We want to see how it works, how it behaves, and what can be done with it,” says Johanna Norén, Amphibious, Support and Base Systems, FMV.
The project under which the unmanned boat, an unmanned surface vehicle (USV), was purchased is a three-year research and development initiative commissioned by the Swedish Armed Forces for FMV. This is because the Swedish Armed Forces aim to build knowledge and understanding of unmanned maritime platforms.
“For example, we can look at the war in Ukraine, where USVs play an important role in the Black Sea. And with this project, we want to build knowledge. For the Armed Forces, it’s about what they want to do with USVs — what is possible, what options exist, and what requirements they can set. For FMV, it’s about procurement — how it should be carried out, whether it can be done faster, and what’s available on the market,” says Robert Sandgren, who works with technical support at FMV.
The project also includes market and regulatory analyses and examines which technologies could be useful for unmanned surface systems within the Armed Forces.
“This gives us important opportunities to learn about the possibilities and limitations we may face in future acquisitions and in the use of these types of systems,” says Agnes Moberg, FMV project manager.
The boat purchased by FMV, the Mariner, is a Norwegian model and is used, among others, by the Norwegian Home Guard and the navies of Spain, Denmark, and Portugal. It was showcased during the recent REPMUS 2025 exercise in the latter country.
“It’s a proven system. The boat has a fairly general design, which allows it, during exercises, to simulate different types of vessels with various operational uses. For example, it can be used to transport payloads to an island or to simulate a boat suitable as a patrol craft. It could also be equipped with sensors that can be lowered to map the seabed. Moreover, the boat is maneuverable enough to be relevant for testing and evaluating different systems,” says Robert Sandgren.
The boat is equipped with cameras in all directions and features Lidar (laser radar scanner), which provides an accurate 3D image of the surroundings and enables safe navigation. It can be remotely controlled manually or preprogrammed with a route, and it also has a certain ability to detect and avoid collisions.
“Even though it’s a proven system, there are still parts of it — including those related to the vessel’s ability to avoid collisions — that have a lower level of technological maturity and that the project aims to explore,” says Agnes Moberg.
During the tests, the boat was remotely controlled and monitored by an operator aboard a manned vessel. Using a controller or computer, it is possible to choose how the boat should navigate and which elements to practice. For the operator on the boat to maintain communication, a connection to a Wi-Fi or LTE (4G) network is required.
Further tests of the unmanned boat will be conducted later this year, allowing for continued expansion of knowledge related to public procurement.
The Mariner is 5.98 meters long, 2.06 meters wide, 2.7 meters high, with a draft of 0.5 meters and an empty weight of about 2 tons. It can reach speeds of over 24 knots, powered by Hamilton Jet waterjets driven by a 196 hp Yanmar diesel engine, and has a range of 100–150 nautical miles or up to 72 hours of continuous operation (fuel capacity is 200 liters, with the option to double it). The hull is made of durable polyethylene. Optionally, it can be equipped with SeaCapture software, support Kongsberg MBR or Starlink communication, as well as SeaSight enhanced situational awareness systems, Class A AIS (Automatic Identification System), and VHF communication.
Video: FMV