ExailECA Group is joining forces with iXblue and becomes Exail Learn more

ROV Planet: ROVING BAT ROV The Right solution for Hull Cleaning and other UWILD applications

Friday, August 03 2018

Published on ROV Planet, July 2018.

Read the PDF 

In context of the Oil & Gas business, this solution is by far more efficient and safe than traditional UWILD methods. Typical interventions are Inspection, NDT measurements and Cleaning. This article will feature a FPSO hull cleaning and inspection operation performed offshore Brazil in early 2018 by Petrus.



UnderWater Inspections In lieu of Dry-docking are now prevailing around the world, for obvious economic reasons. However, they are strictly controlled by international classification societies, since they are required to ensure the structural and operational integrity of any marine asset throughout its operational life span.



ROVING BAT is a hybrid Remotely Operated Vehicle combining a traditional ROV with a crawler, providing a very strong thrust thanks to its 8 powerful thrusters (4 horizontal, vectored and 4 vertical), and equipped with two sets of motorized tracks.

The ROVING BAT crawler swims from the launching point to its target: the ROV embedded sonar system assists this diving-to-docking process when the environment is harsh and/or in turbid waters.

When close to the hull, it automatically tilts/rolls onto the hull thanks to its software guided auto-docking, enabling non-skilled operators to achieve these kind of delicate operation ; it thereafter sticks firmly onto the hull, thrusters securing a much stronger adherence than that offered by magnetic systems, thanks to its its 4 vertical thrusters.

Then it crawls along the hull to perform the close inspection and/or cleaning tasks; when necessary, the additional thrust from the 4 vectored thrusters helps manoeuvring.

The current ROVING BAT is the result of a long evolution which started in 2006 on Petrobras request for a ROV that could crawl along its FPSO hulls to run close inspections and UltraSonic measurements giving birth to the successful design of the first ROVING BAT. Then in 2010 came the increasing demand for local cleaning of the hull: ECA Group started a study of several cleaning techniques, going from mechanical brushing to water jetting and finally adopted the cavitation, in close cooperation with the Cavidyne company. In 2017, ECA Group upgrades the ROVING BAT by adding two additional horizontal thrusters, to improve its capabilities of cleaning operations in strong currents: the combined push from crawler plus thrusters secure an impressive thrust.

ECA Group assess that the ROVING BAT solution is by far more efficient than other traditional UWILD methods, such as divers, conventional ROVs or magnetic crawlers. Indeed, ECA Group recalls the traditional method drawbacks:

  • The divers can’t approach the hull in case of rough or tur - bid seas, present safety hazards and have poor efficiency, hence they generate high costs.
  • The traditional inspection or work class ROVs can’t re - main at close contact with the hull and are inoperable in case of rough seas.
  • The magnetic crawlers need manual handling for docking on hull and face possible loss of magnetic adherence in case of significant marine growths and/or hull irregular shape.


ROVING BAT is particularly well equipped in terms of:

  • Viewing system with a colour zoom TV camera with panoramic viewing through a dome,
  •   A wide angle B/W TV camera with built-in LED ring, and two powerful LED headlights.

Sensors indicating heading (with auto heading function), pitch & roll, depth gauge (with auto depth function) and odometer for crawling mode.

Optionally, ROVING BAT can incorporate a sonar and a digital still camera.

The main applications for inspection are related to the underwater hull and the sea chests.


ROVING BAT embeds a NDT unit fitted at the back of the vehicle, which incorporates:

  • A cathodic protection measurement probe,
  • A metal thickness measurement UT probe which controls the hull thickness,

so as to validate the conformity of the vessel, verify the structural integrity and assess the level of corrosion and wear.



There are two cleaning methods proposed as alternatives.

One is the traditional jetting system where: The ROV incorporates a 5 function electric manipulator arm equipped with a stainless steel cleaning nozzle aside to a micro colour TV camera. This arm is also extremely useful for access into restricted areas ; it can also be equipped with a laser pointer for 2D measurement. The optional CaviBLaster Gun can also be installed on the arm in place of the jetting system in order to increase significantly the power and efficiency of cleaning in confined areas. The CaviBlaster gun is then connected to the (here under described) Double Dome Cavitation HPU connection.

The other solution is the double dome cavitation system, where the ROVING BAT is equipped with a high-pressure water power unit generating cavitation at the end of proprietary nozzles. The system cleans the hull using the energyreleased by the implosion of the bubbles during the cavitation process, causing the marine growths to be removed from the surface. Each dome incorporates rotation nozzles which, besides performing an excellent cleaning job, create a vortex effect, hence increase the ROV adherence to the hull.


The Petrus Group is a major service company devoted to Offshore Oil and Gas. It leads the way in provision of key services to support the International Energy Industry.

Petrustech Oil & Gas LTDA won a tender for the overall inspection of a FPSO laying off Brazil coasts. For this operation a Roving Bat equipped with the double dome cavitation system was successfully used.

Further to this, the Petrus Group offers section services/diverless UWILD solution integrating the ROVING BAT Hybrid ROV.

‘’Our Multi-Purpose Hybrid ROV allows unparalleled flexibility and efficiency in UWILD operations. Able to perform standard ROV observation, fly-by inspection of the hull, hull cleaning, hull thickness gauging and ICCP testing, this is a game changer in diverless solutions, far beyond what the current market has to offer’’ says Daniel Schmidt, Chairman of Petrus Group.”

‘’We successfully experienced Roving Bat end 2017 on a comprehensive class related inspection task (i.e. cleaning, inspection and hull gauging, as per IMO requirements) on an FPSO off the coasts of Brazil.“

“The ROV was deployed directly from the FPSO, hence we didn’t need any support vessel."

The vehicle efficiency in terms of hull cleaning was particularly appreciated: the ROV positioning on the selected spot, the cleaning of marine growths and the thickness measurement: the performance of this hybrid ROV is far above what you can achieve with divers.

“A crew of 4 persons were mobilized for the job, three on the Roving Bat, and one specifically attending the Caviblaster equipment.

“Although I didn’t have the chance of comparing, within the same environmental conditions, the Roving Bat with magnetic vehicles, I feel Roving Bat is better, in terms of adherence on the hull and efficiency. I also want to report that we did beneficiate of a very good technical support from ECA Group. In conclusion, I assess that Roving Bat is technically the best equipment currently available on the market for hull inspection


All international classification societies have specified stringent requirements regarding the UWILD operations in terms of hull examination and cleaning. Specifically, the ABS requirements are the following:

    1. A general examination of 100% of underwater hull including rudders, propellers, propeller shaft clearances
    2. Close visual examination of critical areas ƀ Corrosion protection potentials check and anode survey
    3. Splash zone examination
    1. the cathodic protection
    2. the hull thickness measurements
  4. spot cleaning
  5. or extensive cleaning


As feedback from recent operations conducted on FPSO hulls by our clients with this hybrid ROV, ECA Group assesses that Roving Bat meets 100% of ABS requirements for UWILD hull inspection.


More Maritime news ?
R7 en mer 2 tr
Belgium selects Exail’s R7 ROVs to... MARITIME

Belgian Defense has ordered six R7 Remotely Operated Vehicles (ROVs) from Exail. This...

Read More
Remote Hydrography 2024 | 27 -28 Feb... MARITIME

Exail is exhibiting at Remote Hydrography 2024, from 27 to 28 February 2024, in Dublin, UK.

Read More
Oceanology International 2024 | 12... MARITIME

Exail will be exhibiting at Oceanology International, from March 12 to14, 2024 in London (UK).

Read More
Sea Air Space 2024 | 08 - 10 April... MARITIME

Exail is exhibiting at Sea Air Space 2024, from 08 to 10 April 2024, in Maryland, US.

Read More
CANSEC 2024 | 29 - 30 May 2024 |... MARITIME

Exail is exhibiting at CANSEC 2024, from 29 to 30 May 2024  in Ottawa, Canada.

Read More
Belgium Naval & Robotics
Naval Group launches the first mine... MARITIME

The first of the twelve mine countermeasure vessels of the Belgian-Dutch rMCM programme, the M940...

Read More
Ocean Business 2023 | 18-20 April |... MARITIME

Exail is exhibiting at Ocean Business, from 18 to 20 April 2023, in Southampton, UK, the hands-on...

Read More
Colombiamar 2023|8 - 10 March | Exail... MARITIME

Exail will be exhibiting at Colombiamar, in Cartagena, Colombia, from 8 to 10 March 2023....

Read More
Exail's A18D underwater drone chosen... MARITIME

Exail, a specialist in underwater drone systems, has signed a contract with the DGA (the French...

Read More
HYDRO 2022 | 6 - 8 December | exail... MARITIME

Exail is exhibiting at Hydro 22, from 6 to 8 December, in Monaco, an annual event where...

Read More
copyright 2024 eca group© all rights reserved - legal terms - privacy policy - sitemap - A Groupe Gorgé company