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Hydrographic Exploitation Group puts new survey system through its paces at sea
7 April 2026
A specialist Royal Navy team have tested a new autonomous underwater surveying system at sea for the first time.
The Hydrographic eXploitation Group’s Teams 5 and 6 travelled to Denmark to put a Containerised Remotely Operated Towed Vehicle (C-ROTV) through its paces.
The vehicle, which forms part of the Royal Navy’s transition to a ‘hybrid navy’ is a bespoke launch-and-recovery system for the large ScanFish oceanographic survey system. The towed ScanFish operates at depths down to 1,000 metres – nearly 3,300ft – and contains multiple in-water sensors.
Manufactured by EIVA, ScanFish includes a full oceanographic sensing package, side-scan sonar, a sub-bottom profiler (capable of mapping the subsurface structure, geology, and any objects potentially buried beneath the seabed), and high-end optical and electro-optical cameras.
HXG, based at HMNB Devonport in Plymouth, have been developing the capability of the system and, after liaising with EIVA’s sister company Forcys, deployed ScanFish from the University of Aarhus research vessel RV Aurora.
The container was shipped several weeks ahead of the team flying, ensuring the manufacturer could conduct a thorough set of annual maintenance tasks ahead of the deployment.
Arriving in a snowy Denmark, the Royal Navy personnel spent two days at the EIVA facility in Skanderborg, around 28km south-west of Aarhus, working on the theory of operating ScanFish, routine maintenance and sets of dry drills with the launch of the vehicle in a snow-covered car park.
The C-ROTV was then transported to Aarhus so the team could see it deployed on a ship -which involved more than simply securing the container to Aurora’s aft deck.
Various systems needed to be integrated into the ship’s system, including highly-accurate GPS and underwater positioning sensors, as well as remote bridge screens for the ScanFish and container CCTV system.
Once completed and tested, the team was able to get with on safe launch, recovery and operation of the ScanFish from the container.
With her Master Torbin Vang enjoying more than 20 years’ experience of the vessel – named after the Roman goddess of dawn – Aurora’s crew were entirely at ease with towed underwater sensor operations around the Bay of Aarhus.
“Having a background in traditional ship-based military surveying for almost 20 years, being assigned as the 2i/c of Team 5 and developing the novel capabilities of the ROTV has been a real contest,” said CPO (H) Kirsty Warford.
“Having to think differently about remotely collecting data for multiple sensors at depth while maintaining the need to position the vehicle accurately and precisely up to 4000m astern of the vessel has caused a few headaches! However, deploying to Denmark, working with EIVA and getting the opportunity to visit the home of the inventor of Lego has provided the excitement of new experiences and I’m relishing the ongoing challenge of taking this capability forward.”
The first couple of days were spent going through the rudimentary procedure of moving the ScanFish, an 800kg sensor laden wing, from its fore and aft position in the container, trailing it outboard, astern of the ship, before lowering it into the water, all in one swift confident manoeuvre.
Once the team had proved that it could safely launch and recover the vehicle, they were then able to explore the full range of capability of the system, testing out the tri-frequency side-scan sonar, a sub-bottom profiler, a plethora of oceanographic water sampling sensors, a still camera and laser scanning camera.
The training ended with a test of the emergency ascent drill: an operator ‘flies’ the vehicle rapidly upwards to avoid a seabed obstacle or shoaling seabed.