The solution

Launched in 2018, the OD OBN programme is a research and development collaboration between partners Shell, Petrobras, SENAI CIMATEC and Sonardyne, supported under the Research Development and Innovation funding clause of the Brazilian National Agency for Petroleum, Natural Gas and Biofuels (ANP).The On-Demand Ocean Bottom Node (OD OBN) programme marks a pivotal step in addressing these challenges, providing a disruptive approach to time-lapse seismic data acquisition.

It is a pioneering new system for acquiring 4D seismic data, which delivers more efficient and cost-effective surveillance of complex pre-salt fields. At its core is a long-term OBN system that can remain on the seabed for several years, capturing seismic data that can be recorded and harvested “on-demand” using autonomous underwater vehicles (AUVs), without the need for repeated deployment and retrieval cycles.

Vast quantities of seismic data are harvested wirelessly using an AUV such as Saipem’s ‘Flatfish’, that implements the through-water optical interface to interrogate the OD OBNs, as developed under a separate ANP programme sponsored by Shell.

This AUV data harvesting approach eliminates the need for node recovery, dramatically reducing vessel time, operational complexity and associated costs.

Key Sonardyne technologies include wireless acoustic communications, required for long range recording control and node clock time offset measurement, and Sonardyne’s BlueComm extremely high-speed optical communications for short range data harvesting to a nearby AUV or remotely operated vehicle (ROV).

The results

Over 2,000 days of trials of pre-production nodes have been conducted across various pre-salt fields including Sapinhoá, Itapu and Buzios. These have successfully demonstrated acoustic control, high-fidelity data acquisition and optical data harvesting using BlueComm, as well as comparing OD OBN data with that of other commercial nodes.

The final round of tests concluded successfully in 2025, with results presented at the IMAGE ‘25 conference in Houston and SBGf Rio’25 conference in Rio de Janeiro.

Next steps

A pilot array of 660 pre-production nodes is currently being produced at a brand-new manufacturing facility in Camaçari, near Salvador, Brazil. Hundreds of these nodes will soon be deployed at the Mero field operated by Petrobras for extended testing and performance evaluation.

The long-term vision is to use autonomy and state of the art communications technologies to enable operators to conduct more frequent ‘on demand’ seismic surveys, with higher fidelity data, at a fraction of the cost of conventional seismic survey methods.

This capability will provide clearer insights into fluid movements and pressure changes within the reservoir, helping to optimise production strategies, improve decision making and enhance recovery rates in one of the world’s most challenging offshore provinces.

OD OBN is not just an incremental improvement, but a fundamental shift in how the industry approaches deepwater reservoir management.

Australian vessel operator Tenggara Explorer wanted to see if there was another way. Could DP-level control for ROV-follow capability be achieved on a non-DP class workboat?

Together, maritime autonomy and AI specialist Greenroom Robotics, ourselves and Unique Group equipped the 34 m-long Tenggara Explorer multipurpose vessel with integrated DP-level control and USBL for ROV-follow capability for their client’s medium-size inspection-class ROVs (with the capability to attach the Sonardyne transponder to any unit).

The Solution

The core of the solution was the integration of two key systems, Greenroom Robotics’ autonomy software, GAMA and our Mini-Ranger 2 USBL system.

Greenroom Robotics’ GAMA

GAMA is advanced autonomy software that is hardware agnostic and can be retrofitted to existing vessels to enable remote, hybrid and autonomous control.

GAMA’s Dynamic Predictive Control (DP-C) independently controls thrusters, propellers and rudders using sensor feedback and control algorithms to counter wind, waves and current. This provides DP-level control to smaller more agile workboats, like Tenggara Explorer enabling precision positioning.

As a result, survey teams on smaller vessels can execute complex manoeuvres and survey patterns with high precision, at day rates around 80% less than a DP-class vessel, and with lower risk than manual precision control.

Mini-Ranger 2 USBL

Our industry-leading Mini-Ranger 2 USBL system is engineered for high-performance tracking of underwater targets from surface vessels in shallow waters and coastal environments, providing stable and reliable tracking, even in challenging sea conditions.

It’s lightweight and portable, making it easy to integrate into smaller vessels, even including smaller uncrewed surface vessels (USVs). Installed on the Tenggara Explorer, Mini-Ranger 2 provides the high-accuracy positioning data required to track the ROV during inspection tasks and survey work.

Crucial to successfully integrating these systems onto the Tenggara Explorer was:

• Robust platform integration: direct interfacing with helm, propulsion and auxiliary thruster systems to enable smooth, coordinated actuation.
• Sensor fusion and target tracking: combining GPS, IMU, wind, and USBL subsea positioning data to maintain stable lock on both fixed coordinates and moving underwater assets.

Unique Groups’ team was the crucial integration partner, ensuring the vessel’s complex systems worked together, enabling its transformation to DP-level control and ROV-follow capability.

The Mini-Ranger 2 was expertly integrated into the vessel along with human machine interfaces and GAMA and Sonardyne displays into pre-existing Simrad units on the Bridge. This was followed with extensive in-water testing and performance verification and calibration.

Through this work, Unique Group enabled GAMA to perform critical autonomous functions, including precise ROV following, station-keeping and survey line tracking off Australia’s West Coast.

The Results

Our collaboration with Tenggara Explorer demonstrates how high-precision station-keeping and target-following can be done without the DP price tag. With the integration of GAMA and Mini-Ranger 2, the vessel is proving its ability to deliver DP-level capability, including ROV-follow operations.

Kai Lebens, Director and Operations Manager, at Tenggara Explorer:

“What stood out most was the stability during ROV/AUV following. We consistently held position and heading within DP-equivalent tolerances, even in variable wind and swell, while following a moving subsea target through USBL updates. The feel is ‘DP-like’ – the helm simply stayed where it needed to be, without the constant micro-corrections they were used to.

With GAMA managing fine vessel motion, bridge teams can maintain higher vigilance and focus on project oversight, data quality and safety. It’s also an advancement on the autonomy roadmap – helping to unlock the benefits of autonomy, alongside DP-level control.”

Peter Baker, General Manager of Growth, at Greenroom Robotics:

“Mini-Ranger 2 provided the reliability and fidelity needed for predictive tracking. It provides high update rates, dependable accuracy and stable performance in the shallow-to-midwater environments typical of survey and inspection work.

“That consistency is essential as the autonomy needs trustworthy subsea positioning to predict vessel motion relative to the ROV/AUV. Sonardyne effectively gave us the ‘subsea truth source’ that GAMA’s Dynamic Predictive Control depends on.”

Aidan Thorn, Marine Robotics Business Development Manager at Sonardyne:

“For vessel operators like Tenggara Explorer, it means new mission types – allowing them to use their existing workboat to take on tasks that historically required a DP-class vessel, unlocking a broader variety, and potentially higher-value, jobs.”

“Unique Groups’ integration work was the linchpin that allowed the Tenggara Explorer to fully leverage the GAMA package and Mini-Ranger 2’s capabilities, enhancing operational efficiency and safety while reducing environmental risk,” adds Lebens (at Tenggara Explorer). “Their contribution was fundamental to the success of this project.”

RV Sonne

RV Sonne is a deep‑sea research vessel, about 116 m long and built in 2014 for multidisciplinary work mainly in the Pacific and Indian Oceans.

Clarion Clipperton Zone, Pacific Ocean – Biogeochemical and biological assessment of deep-sea mining crater

Earlier this year, the RV Sonne recently completed an expedition to the Clarion‑Clipperton Zone in the Pacific Ocean to assess the impacts of deep sea mining trials on the seafloor from 2021. Ranger 2 USBL was used to track equipment, including the ROV Odysseus (on dives lasting up to 56 hours!), benthic chambers and sampling platforms, down to the seafloor in about 4,000 m water depth.

Although the scientists were able to use a visually-guided multi-corer, they had to rely on the USBL system alone to accurately position the box-corer onto caterpillar tracks left in 2021. This was particularly necessary to gain larger volumes of sediment required to reach macrofaunal abundances that are statistically significant. Learn more

Southwestern Pacific Ocean – Hydrothermal vent system research

Ranger 2 was used to position the ROV Kiel  6000 during deep‑sea dives, allowing it to navigate accurately enough to reveal a previously unknown hydrothermal vent system, at around 1,300 m water depth, in the Tabar–Lihir–Tanga–Feni island chain of Papua New Guinea. During the expedition (SO299), this precise positioning helped researchers discover the unusual “Karambusel” field, where hot mineral‑rich fluids and methane‑rich gases rise side‑by‑side—an environment not seen anywhere else in the world. Learn more

Eastern Pacific Ocean – Tracking tectonic strain

GEOMAR’s work from the RV Sonne has involved deploying our long‑endurance AMT seabed arrays to monitor tectonic strain along the Nazca–South American plate boundary. These instruments, precisely positioned by Ranger 2 USBL across complex seafloor terrain, capture precise geodetic data from depths of 2,800 m to over 5,000 m. Ranger also reliably tracked and communicate with the instruments during subsequent survey and data‑recovery missions. Learn more

RV Maria S. Merian

The RV Maria S. Merian is an ice‑strengthened research vessel, at 94.8 m long, and in service since 2006.

Atlantic Ocean, off Newfoundland – Collaboration with SAMS for Fetch AZA data retrieval (pre-existing other articles)

Ranger 2 was used to accurately locate and communicate with a Fetch AZA deployed on the seabed by the Scottish Association of Marine Science (SAMS). This enabled the crew to command and retrieve its long‑term oceanographic dataset during a 2024 transit in the North Atlantic, while it happened to be passing through the area. Ranger 2 allowed the crew to establish a reliable communications link with the Fetch AZA instrument, upload its stored measurements and confirm its status on the seafloor with shore-based colleagues, supporting ongoing monitoring efforts in the region.

Data from these sensors is discussed in a recent Geophysical Research Letters paper looking at the use of AZAs in physical oceanography. Learn more

Watch how SAMS is using Fetch

Norwegian-Greenland Sea – Hydrothermal vent research

Using the MARUM‑QUEST 4000 ROV, positioned using Ranger 2 USBL, scientists were able to pinpoint and explore a hidden hydrothermal vent system more than 3,000 m deep off Svalbard—an area where no such activity had ever been confirmed before. During expedition MSM109, this precise seafloor exploration revealed the newly named “Jøtul” field, a rare Arctic vent system emitting super‑heated, mineral‑rich fluids and unusually high methane levels—marking the first hydrothermal discovery along the 500‑km Knipovich Ridge. Learn more

Ionian Sea – Mount Etna Flank Movement

Ranger 2 was used to guide the search for five Sonardyne AMT geodesy stations deployed on the flanks of Mount Etna. This enabled the crew to accurately navigate to their positions at around 1,038 m water depth during the 2024 MSM132 expedition. Although the recovery ultimately failed due to issues with third‑party equipment, the precise acoustic positioning brought the team to within a metre of the first AMT station, demonstrating the reliability of the underwater tracking even under challenging conditions. Learn more

Meteor IV fact file   

Meteor IV is being built by the Meyer-Fassmer Spezialschiffbau consortium on behalf of Germany’s Federal Ministry of Research, Technology and Space (BMFTR)

The ship will replace the previous Meteor and the research vessel Poseidon.

GEOMAR will operate the ship, with its scientific missions planned by the German Research Fleet Coordination Centre (Leitstelle Deutsche Forschungsschiffe) at the University of Hamburg.

One of its first major scientific missions will be the one-year FUTURO research campaign off the west coast of Africa, investigating how climate change and human pressures are altering West Africa’s upwelling system and marine ecosystems.

Overview

When it comes to USBL and LUSBL transceivers, one model does not fit all situations and vessels. For Ranger 2 and Marksman installations, our High Performance Transceiver (HPT) is available two primary configurations.

HPT 5000
HPT 5000 offers full hemispherical acoustic coverage so it’s a popular choice for tracking multiple targets  (ROVs, AUVs, towfish, seafloor sensors) over a wide range of depths and elevations. The unit is also suitable for dynamic positioning reference on survey, research and offshore support vessels.

HPT 7000
HPT 7000 is engineered for ultra-deepwater operations, tracking targets far below (rather than to the side) of a vessel, and also high vessel noise operating environments, as those typically encountered on DP drilling and construction where aeration from thrusters is liable to cause signal interference.

Both models of transceiver fully support 6G LBL operations using Fusion 2 LBL software. They are also highly capable acoustic communications modems, able to interrogate, command and recover data payloads from deployed Sonardyne instruments including AMTs and Fetch. Supporting telemetry rates of up to 9,000 bps minimises the time a vessel has to wait on location to recover data, as well as supporting LBL operations.

HPT 5000/7000s are also available in Gyro USBL configurations offering calibration-free installation and use.

At a glance

• Use with Ranger 2 USBL and Marksman LUSBL systems
• Can also be used to communicate and harvest data from Sonardyne sensors
• Hemispherical (HPT 5000) or directional (HPT 7000) arrays to suit your vessel and application
• Can be deployed other-the-side, through-tube or through-hull
• Suitable for new-build vessels or USBL/LUBL upgrade for your existing vessel

All HPTs are built on our 6G technology platform with multi-element processing to enable transponders to be positioned more precisely, more quickly and more robustly due to improvements in signal processing algorithms and array design.

Functionality such as ‘Discovery Mode’ enables vessels equipped with Ranger 2 and Marksman to enter an offshore area and automatically detect previously deployed transponders (including their configured address and channel), making simultaneous operations using shared seabed arrays possible.

Manufactured in aluminium-bronze, HPTs are intended to be fitted temporarily or permanently to a vessel’s through-hull or over-the-side pole. HPT 5000s (including Gyro USBL 5000s) have also been fitted to large USVs for uncrewed missions controlled from over-the-horizon.

For specialist applications, inverted USBL, LMF frequency and extreme depth range HPT transceivers are also available. Please get in contact to discuss your requirements.

Overview

ROVNav 6+ uses our new Wideband 3 signal technology, which is key to unlocking the benefits of your Fusion 2 LBL system.

It allows, for the first time, sensor telemetry data (e.g. pressure, depth or temperature) from a seabed or structure deployed Compatt 6+ to be embedded within navigation (ranging) data. This change has a big impact on operations such as structure installation, as breaks in tracking to get sensor reading updates at vital moments are now a thing of the past.

Its compatibility with Wideband 3 and Wideband 2 telemetry commands, and support of high power Wideband 2 ranging protocols, proven for their accuracy and robustness, means the ROVNav 6+ offers improved range and acoustic performance in challenging conditions such as on noisy vehicles or in multipath environments.

At a glance

• High power, long range LBL transceiver for ROVs
• Wideband 3-enabled supporting embedded sensor data with ranging data
• Optimised for Fusion 2 and compatible with Fusion 1
• 3,000, 5,000 or 7,000 m depth rated options
• USBL mode for emergency ROV relocation
• Modem mode for harvesting data from Sonardyne logging sensors; Fetch, AMT…

ROVNav 6+ is also a fully functional USBL responder or transponder, compatible with Wideband 2 USBL systems and HPR400. The internal li-ion rechargeable battery pack also enables emergency transponder mode, so if the umbilical and therefore power is cut to the ROV it can still be located by USBL.

The omni-directional remote MF transducer makes installation on an ROV easy. ROVNav 6+ is designed to be rugged and relatively lightweight and utilises robust underwater connectors. ROVNav 6+ supports a range of internal sensors including: strain gauge pressure, PRT temperature and MEMS based inclinometer.

ROVNav 6+ is also fully compatible with our modem and logging equipment such as AMT and Fetch products, allowing it to be used to retrieve data or configure logging regimes. It supports all of our Wideband 2 and Wideband 3 spread spectrum acoustic communication; 100 to 9,000 bps data rates can be selected depending on the environment.

Sensor options include a Digiquartz pressure sensor, precision inclinometer and altimeter interface. This provides a fully featured ROV manipulator deployable tool/sensor pack for a range of different applications including metrology, bathy survey and structure deployment operations, without the requirement for any additional interfacing on the ROV.

Reassuringly reliable Ranger 2

Ranger 2 is more than just an acoustic tracking and positioning system. It goes way beyond tracking; it can be part of a dynamic positioning system, it supports robust two-way data communication with a range of seafloor sensors to collect data, it can support AUV command and control and will even release seabed moorings.

Ranger 2 can even be run from an uncrewed surface vehicle (USV) enabling truly remote, autonomous operations. Whether your mission involves seabed surveys, offshore energy site inspections or commanding a fleet of AUVs, Ranger 2 can help you expand them over the horizon and to the edges of your imagination.

It comes with an impressive list of standard features, our award-winning 6G (sixth generation) acoustic hardware platform and Sonardyne Wideband 2 digital signal architecture. The flexibility of the Ranger 2 family is further extended by our range of 6G transponders to support a wide variety of applications.

Why should you invest?

Our Ranger 2 family gives you the versatility you need, at the investment level you can afford, to get your project completed quickly and efficiently. It’s engineered like no other USBL on the market. Adaptable, scalable and always compact, there is a Ranger 2 USBL to suit any size vessel or project. As your needs grow, bolt-on software packs unlock additional capability and protect your investment. Whichever size suits you best, they will always be compatible with our full range of 6G transponders and many other vessel systems.