Simulating Submarines: An Unrivaled Tool for Anti-Submarine Warfare Training

(Image credit: RTsys)

RTsys, founded in France in 2010, has emerged as a trailblazer in the ocean industry, setting new standards and achieving remarkable milestones by delivering acoustic systems tests and training, torpedo firing exercises, and acoustic signature measurements to Navies around the world.

From its inception, the company has dedicated itself to enhancing trust in underwater technology, a journey that has been defined by innovation, resilience, and a commitment to excellence. Today, the company is part of the SeaVorian group, which has more than 30 years of experience in providing equipment for both marine and naval operations and is now recognized as one of Europe’s leading names in ocean tech development.


The tracking of enemy submarines is an essential task for navy frigates, helicopters, and maritime patrol aircraft (MPA). However, training personnel is expensive. Similarly, training time with submarines is limited and expensive. Therefore, in recent years, Anti-Submarine Warfare (ASW) training targets have become a more accessible, cost-effective means of sharpening the required tactical skills in the field.

To create real-world simulations, Navies need an underwater solution that provides operators affordable, realistic, and quick-to-access training anywhere in the world and one that operates on every low-frequency active and passive sonar. Over the last decade, client requirements have been uniform: drones must accurately simulate a submarine during training; they must be cheap, portable, reusable, and give a realistic acoustic response within their peripheral frameworks. In response, SEMA was created in 2015 and continues its ongoing development.


SEMA is an autonomous, recoverable, acoustic target dedicated to ASW training. It is designed to be operable from all kinds of platforms, such as surface ships, submarines, helicopters, and ASW aircraft. Rapid to deploy from both a RHIB (rigid-hull inflatable boat) or a vessel, its navigation route is plotted with waypoints or segments. Different types of training modes can be programmed, such as passive, active, and combined acoustics. As well as being easy to launch, operate, and recover, SEMA is reconfigurable in one hour with a spare battery.

The two-meter-long SEMA is highly portable, weighing in at a mere 33 kilograms. It offers unrivaled acoustic and kinematic performances while keeping the strong skills of a light target easy to deploy and recover from any kind of watercraft (from RHIB to frigate). SEMA can navigate down to 300 meters depth during 24 hours at 4 knots and up to 1.5 hours at 15 knots to simulate evasive maneuvers at full speed.

Thanks to its secured, high-capacity battery (which is easily rechargeable on board), navigation skills combined with GPS repositioning also offer optimal and increased surface localization conditions at the end of the mission.


SEMA offers several types of acoustic training capabilities: acoustic echo-repeater: (1 to 33 kHz) with 5 bands for active sonar frequency and 2 bands for active homing torpedo; 6 Narrowbands: 200 Hz to 38 kHz; 2 Broadbands: 450 Hz to 8 kHz and 10 to 23 kHz; and an acoustic recorder with data encryption.

These acoustic features allow the armed forces to train in authentic conditions, as if identifying and tracking a submarine by offering an acoustic signature simulation and response to latest-generation LFA sonars and homing torpedo heads, putting crew at the heart of operational scenarios by surprising it with kinematic escapes.


Various enhancements have been made to the platform over the years following direct feedback from Navies that have been using SEMA for a decade now, including but not limited to French, Dutch, Belgian, and Indonesian forces.

Continuous improvement efforts to date have centered around safety of use, safety in transport and onboard (UN38.3 air transport compliance and IATA certified), data security, UHF surface localization module, escape capability, magnetic anomaly detection, or constantly evolving functionalities of the user-friendly and intuitive HMI.

SEMA’s modular design architecture allows RTsys to respond to customers’ specific needs, such as integrating custom buoyancy for freshwater training or different battery configurations for longer endurance missions or quicker turnaround times (recharge and redeploy).

A NATO-preferred tool for ASW training, SEMA has become the gold standard solution for efficiently simulating a submarine while giving every operator the capability to debrief its exercises.

Also used as a dynamic tool for sonar range prediction and torpedo firing exercise of the latest generations (e.g., MU-90, A244-S, Mark54, F21, etc.), RTsys recently announced the current production of a significant quantity of targets to be delivered in 2024, and several contracts are still under discussions with high-level Navies.

This feature originally appeared in ON&T’s March 2024 issue. Click here to read more. 

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