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T18-M is a self-powered towed interferometric synthetic aperture sonar (SAS) for Real Time Detection, Classification and Mapping (SCM) of seabed and moored mines. It is equipped with a thinner umbilical cable and a lighter equipment for easier deployment from a USV or another platform.

The T18-M is a towed vehicle derived from the A18-M. It is specifically designed to meet all recommendations related to mine warfare operations (particularly the detection or classification phases).



Energy independent, it enables the optimization of the USV and its performance

One of its features is that it is self-powered like an AUV, which reduces the diameter of the towing cable, which no longer has to incorporate the power supply wires of the towed vehicle and the sonar. The reduced cable diameter results in less drag, enabling the vehicle to dive deeper or reach higher speeds.

By reducing the umbilical cable’s diameter, the size of the towing winch can also be reduced, thus reducing its weight and required power. The reduced load results in a smaller and lighter winch, which in turn minimizes the integration constraints on the vessel or the USV from which it is used (propulsive power, weight and space).


Positioning accuracy

The T18-M vehicle is equipped with a fibre-optic gyroscope (FOG) inertial navigation system (INS) assisted by a USBL (ultra-short baseline) system on the USV, to ensure very accurate positioning of the detected objects in minefields.



60 years of experience in towed sonars

The T18-M vehicle also benefits from Exail's expertise in towed systems for mine warfare since the middle of the 20th century. This know-how is made up of design methods (in hydrodynamics, piloting, etc.) and operational experience during sea trials which have enabled the development of its design software for towed vehicles:

  • DUBM 41 minesweeping vehicle for the French Navy
  • LAGADMOR vehicle, carried out for the French Ministry of Defence
  • MJ2000 vehicle, produced for the German company Atlas Elektronik
  • TOWSCA system, composed of a vehicle equipped with a Side Scan Sonar and a LARS system on board INSPECTOR USV


Dual-use with the A18-M AUV, reduced logistical footprint, economies of scale

The T18-M uses 80% of the A18-M's elements, notably the middle (the battery in particular) and rear (not including the engine/propeller assembly) modules. The front module is directly adapted from the front end of the DUBM 42 and MJ 2000 vehicles.




T18-M is self-powered. Without electrical conductors, the towing cable can be smaller and lighter which has several advantages:

  • The performance of towed sonar at great depths is very much related to the drag of the cable and therefore to its diameter. As a result, the T18-M has outstanding navigation performance even when a long cable length is in the water and even at high sea speeds thanks to the reduced diameter of the cable.

  • A smaller cable can reduce the size and power of the winch on the carrier boat and the towing power requirement, and therefore the size of the boat's engines, which is particularly important when towed sonar is launched from a USV (The drone reduces crew exposure to the minefield). In order to avoid too large motherships, the USVs shall be as compact as possible: The smaller the USVs are, the smaller will be the boats which embark them.

  • Energy on board the towed vehicle avoids having an electric generator on towing boat, which saves space and weight (very useful for a small USV) and provides as well greater operational reliability and greater safety (electrical) for crew when operating towing boat.


  • Up to 18kts mine hunting operations
  • 3D high resolution & coverage rate surveys
  • Low installation constraints
  • Easily deployable from various platforms
  • Common design, spare parts & logicistic optimization with a18­m AUV

umisas sonars

The T18-M towed sonar is equipped with a UMISAS 240 SAS sonar.

The UMISAS sonars on board the A18-M AUV and T18-M towed sonars are interferometric synthetic aperture sonars (InSAS) that aim to obtain a spatial resolution in the order of 3cm x 3cm to best classify small and irregularly shaped objects (in the order of 50cm on the side perpendicular to the sonar's axis of view).

The positioning of the support required to form the synthetic antennas is an integral part of the UMISAS process. UMISAS directly uses the data from the A18-M or T18-M inertial unit to perform SAS processing, thus eliminating the use of navigation sensors dedicated to the SAS sonars on the market, which are less efficient and therefore do not allow geo-referencing of the images formed, and above all are much less reliable.

In order to navigate with the precision required for the SAS, the UMISAS sonars use a technique protected by an Exail patent.



  • STANAG 1364 compliant


  • Navies
  • Defence operators
  • Homeland security operators


  • Underwater mine warfare
  • Mine detection and localisation
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