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Remotely Operated Vehicle for Asset Recovery utilising controllable buoyancy

Page last modified
September 2 2023

What is ROVAR

o Patented cryogenic ‘ROVAR’ technology (“Remotely Operated Vehicle for Assets Recovery”)

o Variable Buoyancy System which exploits the properties of cryogenics for controlled subsea lifting and handling operations.

o Precise descent and ascent is achieved by vapourising liquid nitrogen to displace seawater from buoyancy caissons

o Key components

  • Liquid Nitrogen dewar
  • Gasification system including actuators and cryogenic valves to provide heat exchange and flow control of gas into the caissons
  • Actuated relief (dump) valves to retain gas within caissons, and to release it from them
  • Primary sensors – depth / pressure gauge, sonar (distance from seabed), load cells
  • Advanced control system – controls flow of gas into and out of caissons which adjusts buoyancy dependent on depth, load, rate of ascent or descent required
  • Data and power umbilical to control console
  • In-built thrusters control lateral motion with standard or bespoke toolsets and grabs for handling

o Operates in unitary (10+/- tonnes) and multiplex modes for manoeuvring of much heavier loads requiring multiple lifting points due to shape, uneven load distribution etc.

o Lift repeatability – inherent design provides capability for repetitive tasks whilst remaining in-situ and minimising support vessel time

o Practical operating depths - down to 2,000 msw 

ROVAR with Manipulator Grab
ROVAR with Manipulator Grab
ROVAR with Clamp
ROVAR with Clamp
ROVAR with Manipulator Grab
ROVAR with Manipulator Grab
ROVAR with Scoop Net
ROVAR with Scoop Net


Asset Deployment Benefits (ADB) - Increased productivity and effectiveness with same costs
ADB - Increase in subsea capability through multi-tasking
ADB - Enhanced capability for lifting, diving and support vessels
ADB - Parallel surface and underwater tasks for repetitive projects
ADB - Increased scope for projects and reduced time per task
ADB - Adding capability and capacity to all types of vessels
ADB - Environmental and noise footprint reduced
Asset Recovery Benefits (ARB) - Increased efficiency and economy with less costs
ARB - Reduction in costs and time through use of smaller vessels
ARB - Reduction of vessel lifting costs and time on station
ARB - Leverage vessels of opportunity for bespoke immediate lifting
ARB - Multi-tasking of surface and underwater operations
ARB - Environmental and noise footprint reduced with smaller vessels
ARB - Risk reduction with less backdeck usage and smaller vessels
ROVAR is preparing for field trials and for its first commercial deployment


Caissons Open bottomed GRP buoyancy caissons (min 2 per system) which can be independently controlled
Liquid Nitrogen Dewar Pressure vessel design comprising stainless steel inner and carbon fibre outer, with insulation in between.
Gasification system Pressure build circuit in dewar, actuated cryogenic flow valves, heat exchange piping exposed to sea water
Load bearing 'rings' Carbon fibre load rings with load cells attached to selected grab mechanism
Sensors and ancillary equipment Depth/pressure, sonar (distance to seabed and other obstructions, gyros, lights, cameras, navigation
Thrusters Vectored thrusters to enable neutrally buoyant system to travel in horizontal plane
Actuated relief valves Within caisson to allow controlled retention or release of nitrogen, thereby varying buoyancy levels
Control system Hardware and software, power and data umbilical, to remotely control lifting operations from topside console

Relative Business Impact


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Technology Readiness Level


Development Technology demonstration Mature / Proven
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Smarter Subsea Handling (SSH) is a pioneer in controllable cryogenic buoyancy systems for transforming subsea operations of the offshore energy sector.

At the heart of this technology is ROVAR (Remotely Operated Vehicle for Asset Recovery) which has been designed and tested to provide a safe and cost-effective, complementary and alternative solution for subsea handling and buoyancy based lifting services. Our underlying, globally patented technology, can be deployed in its own stand alone designs, such as 'ROVAR', or incorporated into, or integrated with, Autonomous Underwater Vehicles (AUV) and Remotely Operated Vehicles (ROV). 

ROVAR can be deployed to drive down costs, improve efficiency and reduce carbon emissions across multiple operations:

  • inspection, repair and maintenance
  • subsea equipment installation, handling and removal
  • expanded operating scope for marine support vessels and remotely operated vehicles
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