Craig English, Operations Director of Subsea Services at Briggs Marine, outlines the benefits and limitations of using Remote Operated Vehicles (ROVs) and explains why divers can still be a reliable and cost-efficient choice.

Global offshore diving activity is still very much alive and well in many parts of the world, but for the UK, it’s in decline. This is mainly because of the plummeting oil and gas market which has in turn, resulted in less investment in the North Sea.

In comparison, inshore diving is much more active and diverse, comprising a range of activities including sewage works; offshore wind farms; bridge inspections; harbour construction; and underwater surveys. Indeed, there are just as many inshore dive companies now as there were back in 2000, demonstrating that despite the advancement of technologies such as Remote Operated Vehicles (ROVs), divers are still considered a cost effective and reliable option for these types of projects.

That said, ROVs have become more prolific for underwater operations. From eyeball ROVs through to work class ROVs, these technologies are delivering notable advantages on an exponential scale.

Deployed for smaller diving projects to carry out diagnostic work, the eyeball ROV which is small in size and weight with a camera and lights, can be particularly advantageous when looking to resolve problems underwater. This is where visibility is good and current/tide/flow is minimal, in locations that the diver may not be able to easily access such as a sewer, pipeline or small cavity, or where there is a significant hazard. Given their size, these ROVs are a cost effective alternative and can be quick to deploy, with minimal manpower and supporting surface equipment.

Larger in size and weight, inspection and construction class ROVs have more advanced tools and can therefore be deployed for more complex situations, including survey work. Increasingly, these ROVs are being committed to deep water operations for protracted durations as technology advances. Capable of operating in deep water and strong currents, work class ROVs are at the high-end of the ROV spectrum with enhanced technologies including robotic arms that can fix issues in real time.

Despite the digital revolution which has provided the opportunity for these ROVs to push the technology boundaries and create impressive capabilities, the cost to deploy and the reliability and agility of these machines are still significant barriers that need to be overcome. In many situations, divers can still be the preferred choice.

Deploying an ROV for a specific underwater task requires preparation and can take many hours of engineering to design and fabricate equipment prior to entering the water to tackle the issue. If faced with an emergency or evolving situation, this preparation becomes a significant hurdle and is easily rectified with divers who can apply standard technology readily.

Cost is also a significant factor that influences decisions. Although the deployment of an eyeball ROV may not be a huge investment, they do have technical limitations and therefore, may not align with what’s required for the project. The cost of deploying the larger, more advanced work class ROVs can run into millions due to the range of surface assets needed to support and control it such as a vessel, generators, transformers, and launch and recovery systems. This is a huge investment for many businesses who are struggling in a market that has been heavily hit by the global health pandemic and an energy price slump.

Depending on the circumstances and task, divers can still be considered a more attractive and cost effective option – their flexibility, intuition, experience and diversity allow them to adjust and adapt to changes out in the field as and when they need to, which can be the difference between success and failure on an underwater task.

Whilst the advantages of divers over ROVs are notable, we cannot ignore the fact that having humans in the water carrying out various operational and maintenance tasks, like any human related task, poses a risk and there will come a time when the use of divers will cease. However, we’re a long way off this scenario. This can only happen when a wider range of ROVs are manufactured to suit specific and niche situations that previously only divers could tackle. Crucially and particularly for the inshore diving sector, the through life costs of advanced robotics will need to be reduced significantly.

We have seen the advancement of robotics in self-driving cars, unmanned aircraft and unmanned survey vessels and as technology improves and becomes more cost efficient, we will continue to witness advancements into all kinds of vehicles — including ROVs.

One of main reasons we have not reached that point already is down to cost. Innovation often strides ahead but can often come with a high price tag, and so we will only see the displacement of divers when ROV technology delivers increased capability at an attractive price point.