Euronaval 2026 – BAE Systems Bofors Sea Tridon family: a flexible C-UAS hard-kill solution based on a well proven gun

In 2024 BAE Systems unveiled at Eurosatory its Tridon C-UAS system, a truck-mounted version of its well known Bofors 40 Mk4 naval gun. Now Tridon is coming back over water, becoming the Sea Tridon, designed to cope with the drone threat from naval platforms and not only

The Bofors 40 Mk4, which appeared on the market around 10 years ago, is in service with several customers: “Among those we have obviously the Swedish Navy, the Finnish Navy, we have Brazil, in the UK the Royal Navy will have it on the Type 31s, the Royal Netherlands Navy has it as a secondary armament on their new frigates, and both the Royal Netherlands Navy and the Belgian Navy have it on their mine countermeasure vessels that are currently in production. We also have a few others, such as the Japanese Coast Guard,” Stefan Löfström, BAE Systems Bofors Director Marketing and Sales tells EDR On-Line.

Following the launch of the land-based version, some naval customer expressed an interest in a similar solution aimed at naval applications, “So now we are circling back, basically taking the naval gun from naval to land and back to naval again with the integrated fire control,” Löfström explained.

The existing Bofors 40 Mk4 40 mm L70 gun mount is therefore giving birth to a whole new family of systems, known as Sea Tridon.

The basic Sea Tridon is an Mk4 with an electro-optical (E/O) fire control solution based on an E/O director, an internal fire control computer and the relevant software and a ballistic kernel. This may evolve with the addition of new functions such as automatic tracking and target detection and identification, possibly based on artificial intelligence (AI) algorithms, such options being considered as part of the development programme, EDR On-Line understood. The Sea Tridon has an integrated 30-round primary magazine, but if the ship dimensions allow an optional below-deck loading can be added with 70 more rounds. Depending on the ship, the system can receive cueing from longer-range sensors mounted on the same platform, or get them via datalink from another platform, or operate as a stand-alone system, in that case with lesser detection range and capabilities, especially against fast moving targets such as jet-powered drones.

The second member of the family is the Sea TridonC, the “C” standing for “containerised”. This variant is aimed at those naval and maritime platforms that are not usually fitted with such type of defensive assets, but have to operate temporarily in critical areas. Fitting the system before entering the dangerous area, a choke point such a strait (of Hormuz?) and removing them at the other end, fitting them again on a ship going in the other direction might be a viable solution, once legal and ethical issues will be solved, especially when installing such a system on a merchant ship. In the Sea TridonC the gun is fitted on top of a 10-foot container which hosts a 60-round ammunition carousel similar to the below deck solution. Command and control items can either be installed within the ship itself, which would probably increase installation time, or installed in a second container that might also host a radar for better situational awareness, getting those information from external sources remaining an option. The container is obviously purpose made not only to withstand the gun recoil, but also to distribute it on the ship deck, which in case of a merchant ship is not designed to cope with such impulse. “I would recommend a 20-foot container, so you can have at least double the amount of ammunition in the container. And you can also then have a compartment for command and control equipment,” Stefan Löfström said, underlining that his will further decrease the stress on the ship deck.

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“The top of the line of the family is what we refer to as the Sea Trinity. Here we go to a full radar-based fire control system to create a fully stand-alone solution, making it a close-in weapon system based on our Forty,” the BAE Systems Bofors representative said, this version being able to carry out fully autonomous engagements. The model seen at Euronaval was fitted with a rotating radar turret on top of the gun mount and AESA fixed face radar antennas on the mount sides, one of the two solutions being possible; EDR On-Line understood that the Sea Trinity is radar agnostic and that BAE Systems is currently in discussions with a couple of partners that might provide the radar solution, while being ready to accept customers choice for that RF sensor, which would of course need integration. “We are doing the fire control software internally, but sensor systems, either the electro-optical or the radar, will come through our partners,” Löfström stated.

Market wise, the starting point for this family of new products is the existing Bofors 40 Mk4 customer base, but in parallel the company has ongoing conversations with “a handful or two handfuls” of potential customers. “We don’t have yet a launch customer but we have some advanced discussions with different customers. So, hopefully, it will be announced soon,” Löfström stated.

Being heavily based on the land Tridon, and being a comeback at sea for the Bofors 40 Mk4, risks are minimal. As for the land version, in 2027 BAE Systems Bofors will start deliveries for Tridon systems ordered by Sweden and Ukraine.

A gun is effective as long as the ammunition it uses is effective against the intended target. “The unique selling point with these systems is our 3P ammunition. It was developed in the 1990s for the Swedish CV90 programme,” he explained. At that time the main threat were armed helicopters and missiles however the 3P proved its value also against drones, BAE Systems Bofors explained. “We have tried it a lot lately, especially in the land application for the Tridon system. We have successfully engaged a lot of different drones, ranging from the really small quadcopters to FPV drones up to Shaheed-like high-speed drones. We have not made any changes to the warhead as it turned out to be very efficient. We have made some small optimization of the fuse to be able to detect those really small drones,” Stefan Löfström explained.

A very flexible system approach for integration on different types of vessel, from full-fledged warships to the OPVs or patrol boats to even commercial vessels, the Sea Tridon family might require also a new business model, especially for the containerised variant, that may be provided to non military entities. “Right now, to begin with at least, we are aiming the traditional naval customers to buy from us and then put it on a commercial vessel of their choice, if they need. I could see a scenario in the future where we sell the guns to others, but not right now, not to start with,” we were told.

National authorities providing the systems to be installed on merchant ships that need to cross the critical area, and then removed, eventually systems being manned by military or law enforcement personnel, possibly also providing long range detection from land- or ship-based radars might be a scenario solving some of the rules of engagement and ethics issues.

Looking forward BAE Systems Bofors is considering using Sea Tridon on board uncrewed surface vessels, using them for example as C-UAS pickets capable to stay a sea for weeks without human support, min issues being gun maintenance and of course reloading after action, the need for a higher number of rounds being one that needs to be addressed.

Another issue is the type of target; while the threat coming from the sky is definitely a major issue on today land and sea battlefields, the latter brings also another threat, the one posed by unmanned surface vessels, USVs in short. Beside these we find also semi-submerged drones, which pose a great issue in terms of detection, Stefan Löfström explained. The Sea Tridon family is of course capable to deal with that threat, and the 3P ammunition proved once again effective. However in some areas fishing boats attacking commercial vessels have proved difficult to neutralise due to the thickness of their wooden hulls and superstructures. New variants of USVs with increased protection might also appear to defeat defensive systems. “We are looking at those issues as well, to develop maybe a new surface ammunition that is specifically designed for that. But should we need to have a more specific surface target ammunition, we are looking into this right now with our engineers,” the BAE Systems Bofors representative concluded.

Photos by P. Valpolini