BAE Systems has unveiled a family of modular naval gun systems built upon the combat-proven Bofors 40mm system.
The family includes a containerised version of the Sea Tridon that could arm merchant ships, and a complete close-in weapon system (CIWS) that can counter fast-moving threats such as anti-ship missiles, drones and aircraft.
The announcements were made at Euronaval 2026 in Paris, a naval defence and maritime security exhibition showcasing the latest developments in the sector, from autonomous systems and drones to cyber defence and electronic warfare capabilities.
The new family comprises Sea Tridon, Sea Tridon C, Bofors 40 Mk4 Naval Gun and the Sea Trinity.
Sea Tridon
A maritime adaptation of the Tridon Mk2 – an anti-aircraft system specifically designed to be mounted from the back of a vehicle – the naval variant Sea Tridon will combine the Bofors 40mm gun with an integrated electro-optical fire-control system.
BAE says it will offer greater operational independence while simplifying integration.
Sea Tridon C
A containerised version of the system, it can be rapidly installed and deployed on military, government and commercial vessels – including merchant ships – that require temporary or mission-specific self-protection.
"The maritime threat landscape is evolving rapidly, creating a growing need for flexible and effective protection solutions," said Lena Gillström, president of BAE Systems Bofors.
"With the Sea Tridon, navies and maritime operators can select the capability level that best meets their operational needs while benefiting from a common platform, proven technology and advanced programmable ammunition."
Bofors 40 Mk4 Naval Gun
Described as a "modern, compact and lightweight naval gun system," the system is designed for integration with ship combat systems.
With a rate of fire of 300 rounds per minute and a maximum range of 12,500 metres, it can protect against both air and surface threats.
In 2020, BAE Systems was awarded a contract to supply the Royal Navy with 10 of these platforms for its incoming Type 31 Inspiration-class, which are due to enter operational service by the early 2030s.
The system has been procured by nine countries in total, including Brazil, Japan, Sweden and Finland.
Sea Trinity
Described by the company as the most advanced member of the family, the Sea Trinity combines the Bofors 40mm gun with its 3P ammunition and an integrated radar fire control.
It is a complete CIWS, designed to counter missiles, drones and other high-speed targets.
BAE Systems is pitching the system as a direct competitor or modular replacement for existing weapons like the Phalanx, used by the Royal Navy as a last line of defence against anti-ship missiles, aircraft, drones, and fast-attack craft.
Programmable ammunition
Every variant in the new family is compatible with all Bofors 40mm ammunition, from legacy rounds to the modern 3P round.
Developed by Bofors, the 3P ammunition can be configured immediately before firing and offers six programmable fuse modes tailored to different target types.
According to the company, the ammunition can be used against air, surface and shore-based targets, allowing operators to handle multiple threat sets with a single ammunition family.
These include a time mode, which can be used against soft, concealed, or shore-based ground targets which detonate at a pre-set time of flight.
Also available is an armour-piercing mode, featuring a delayed-action fuse that can penetrate light-to-moderate armour protection before detonating inside or behind the barrier.
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