BAE unveils modular 40mm naval gun family

BAE Systems has unveiled Sea Tridon, a new modular 40mm naval weapon offering, at Euronaval 2026. The 3 November launch places Sea Tridon, its containerised Sea Tridon C variant, and the radar-equipped Sea Trinity alongside the established Bofors 40 Mk4 naval gun, creating a four-part family based on Bofors armament and 3P programmable ammunition.

The four configurations offer different combinations of sensors, fire control, and platform integration while retaining the same 40mm ammunition family. A patrol vessel requiring local electro-optical control can use a different installation from a combatant relying on a shipwide combat management system. A support ship seeking mission-specific protection faces further constraints because available deck space, power connections, and equipment access may have been allocated to other tasks.

Sea Tridon adapts the Tridon gun concept for maritime use by pairing a Bofors 40mm weapon with integrated electro-optical fire control. Local optical tracking and a corresponding fire-control arrangement are intended to make the gun less dependent on an additional shipwide surveillance installation for each engagement. BAE Systems has not specified the precise location of every sensor or computer in the announced configuration, so individual mounting and stabilisation arrangements remain matters for platform integration.

Installing a maritime gun requires a structure capable of taking its mechanical loads, electrical and control interfaces, and firing sectors that protect the vessel’s own equipment and personnel. The work becomes more complex when the hull was not initially designed for the weapon. Movement in a seaway, nearby masts, deck machinery, and the way ammunition is handled all influence the eventual position and permitted operation of the installation.

Sea Tridon C packages the same general weapon approach in a containerised arrangement for temporary or mission-specific protection. BAE identifies military, government, and commercial vessels among the intended users. The container changes how a system might be moved between platforms, while each installation still has to account for the strength of its deck, electrical services, ammunition arrangements, and safe operating sectors.

Moving an installation between vessels would also require repeatable connections, transport procedures, and operating checks before firing. These activities sit alongside training and maintenance, particularly where a crew normally operates the ship without a permanent naval gun. The launch material gives no standard fitting time or mass for Sea Tridon C, leaving its installation requirements to be established for individual ship classes.

Sea Trinity occupies the more integrated end of the range. BAE combines the 40mm gun with radar fire control and 3P ammunition, presenting it as a close-in weapon system for missiles, drones, and other fast-moving threats. Radar provides measurements that can support tracking through conditions where electro-optical systems may be limited, while the engagement sequence must account for closing speed, target behaviour, and the ship’s own motion.

Sea Trinity is intended to bring radar-based control into a complete close-in weapon system rather than simply adding another standalone naval gun. Its local engagement functions would still have to coordinate with warning sensors, other weapons, and the vessel’s own command arrangements. Overlapping fields of fire and separate engagement decisions make the interface between a close-in weapon and the wider combat system a significant part of acceptance testing.

The Bofors 40 Mk4 remains the conventional ship-integrated naval gun in the range, with integration into the ship’s combat system rather than the complete independent sensor arrangement described for the newer members. Retaining common ammunition provides a basis for shared stocks, crew familiarisation, and technical support, although the sensor and fire-control equipment still differ between configurations.

Bofors 3P ammunition can be set immediately before firing to one of six programmable fuze modes suited to different target types. A common round can therefore be used across air, surface, and shore engagements while the selected setting and the weapon’s firing solution determine its intended effect. The ammunition does not give every platform the same detection capability: the gun’s engagement performance also depends on the fitted sensors and control system.

The fuze-setting process links the ammunition with the fire-control installation. Correct programming has to be incorporated into the firing sequence, with compatibility and reliable operation checked alongside the gun, sensor, and control interfaces. Where an existing Bofors user considers another member of the modular family, ammunition commonality would simplify one part of that integration while leaving the new sensing and mounting arrangement to be assessed.

The threat mix used to define the family includes small uncrewed aircraft, fast surface craft, and missiles, which place different demands on tracking accuracy and engagement timing. Electro-optical control, radar fire control, and a containerised installation address different operating conditions rather than offering interchangeable levels of protection on every ship. The selection will depend on the platform and its wider defensive equipment.

BAE Systems has introduced the family as a configurable product range rather than reporting a new naval installation contract. The next practical milestones will be customer-specific integration and acceptance of whichever combination of gun, sensor, and fire control equipment is selected. Across the four offerings, Bofors 40mm weapons and 3P ammunition remain the common industrial components.