“Last year I bought a new Apple iPhone, with the expectation that its battery would last up to two days, in line with Apple’s claims. The reality, however, was that this only holds true under light use. Day-to-day, I still find myself charging it by the evening. It’s not misleading as such, but it does highlight the gap between best-case performance and real-world usage.
“That same gap exists in the subsea world, where offshore operations rarely take place in ideal environments. Strong currents, restricted access and low visibility can quickly push Remotely Operated Vehicles (ROVs) to their operational limits when working on complex infrastructure. Yet performance is often still framed around optimal conditions, rather than how systems behave when it really matters.
“From my background in ROV operations, I’ve seen first-hand how critical it is - even at the early stages of tendering - to understand how a vehicle will perform in specific environments and configurations. It’s these factors that directly influence downtime, operational efficiency and ultimately project revenue.
“That’s why we set out to test our VALOR ROV against an alternative ROV in simulated high-current conditions, and to go beyond standard testing approaches to better reflect real operational performance as currents increase.”
Why high current capability matters
“When ROVs struggle in high currents, it can quickly derail a survey or inspection project through timeline delays, reduced data quality and increased costs.
“For instance, if an ROV is unstable, it will collect too much data than what is required which adds noise. This leads to longer post processing of the data, which can delay the deliverable turnaround and ultimately increases the cost of the project.
“ROV instability also narrows the available weather window for completing subsea work. If a vehicle struggles to hold station in stronger currents, this may lead to downtime and additional vessel costs as a result.
“For offshore projects where vessel time is one of the largest cost drivers, even relatively small delays can have a huge impact on overall project budgets and schedules. This makes understanding your systems and testing them in similar conditions critical.”
Where bollard pull fails to reflect
operational reality
“The most commonly used metric for comparing thrust performance in ROVs is bollard pull, which measures the static thrust an ROV can produce while held at zero forward speed.
“However, this test alone fails to account for real-world operational conditions. The static nature of bollard pull as a measurement means it doesn’t consider hydrodynamic drag which will happen once the ROV is moving through the water.
“Bollard pull provides a baseline capability, while actual current operability depends on several factors, such as;
- ROV frontal area and shape
- Drag coefficient
- Tether drag
- Vehicle orientation relative to
- the flow
- Thruster layout
- Real‑world
- thrust curves
“Essentially, this makes it impossible to accurately predict the current an ROV can operate in using the bollard pull measurement alone.”
Why we tested beyond forward thrust
“ROV performance has traditionally been tested based on its forward thrust and forward speed. However, an ROV has a much larger side profile than facing head-on. This means the sides of the system will experience much more resistance when exposed to high-current conditions.
“Lateral thrust and lateral speed become the real limiting factor when subsea conditions are challenging. Its this metric which reveals the truth around how well an ROV can maintain its position and operate effectively in high currents.
“Not only that, it’s also crucial to understand the performance of an ROV system with equipment that will be fitted during real-world operations, such as tooling and sensors on a skid, which ultimately increases the area of ROV exposed to the current. If you don’t mimic operational reality in your testing, you go into a work scope with limited knowledge of your ROV’s capabilities and put project timeline and budget at risk.”
Putting the ROVs to the test
“We visited a test facility to validate the VALOR ROV’s capabilities in an environment that could mimic the conditions of a high-current, shallow water setting. This would mean we could truly put VALOR to the test in its lateral current handling capability, both on its own and with inspection and survey skids attached.
- We tested VALOR up to the maximum current for both forward and lateral operations
- We also tested the ROV on its own, and with multiple different skids fitted
- Finally, we tested VALOR’s performance against a comparable ROV from a different manufacturer
“This would give us a stronger understanding of how VALOR performs during real-world operations with tooling and sensors attached. As a result, this would unlock a range of insights for our clients, from better operational planning, to de-risking their weather downtime and contractual promises to the end client.”
Key findings and the impact on subsea
inspection scopes
“The testing showed that VALOR presents a number of benefits for subsea inspection and survey companies, compared to other systems. Firstly, it decreases downtime by opening up the weather windows, meaning less time in field to complete a scope of work - and subsequent vessel cost reduction.
“VALOR’s stability in high currents also means that data intensive operations, such as photogrammetry, can be completed quicker in the field and enable a faster turnaround of deliverables by speeding up the data processing.
“Finally, VALOR’s high performance with skids, tooling and sensors attached offers inspection and survey companies the flexibility to conduct operations that are not usually possible or optimal for smaller vehicles, such as cable tracking.
“Overall, by testing VALOR against an alternative ROV of a similar size, we were able to prove that VALOR’s ability to hold station in high currents is far superior to its competitors, as it outperformed the alternative ROV based on highly superior lateral performance – again, the true indication of operational limitations. Ultimately, this leads to faster project turnarounds, enhanced data quality, and reduced vessel cost.”
Want to see the proof?
To access the full results of our ROV testing, download the case study below…