Fairlead replacements for Equinor in the North Sea

In 2019, Equinor hired OceanTech to replace riser protection net fairleads at the Snorre A platform in the North Sea. The project has enabled Equinor to continue production without costly disruptions.

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Skilled personnel and collaborative approach key to successful Riser Protection Net (RPN) replacement

- The Riser Protection Net (RPN) replacement has enabled Equinor to continue its Heidrun operations without costly disruptions, Ståle Karlsen, Project Manager at OceanTech, said.

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Robotic solutions vs. divers in splash zone operations

OceanTech’s robotic solutions for splash zone operations do not require the use of any offshore divers. This provides several benefits to your business, including improved safety, significant cost savings, and reduced carbon emissions.

Improved safety

Using divers in offshore operations generally carries significant risks. The environment presents a number of hazards such as poor lighting, restricted oxygen supply, and sometimes extreme temperatures or pressures. 

Offshore diving risks, however, are not limited to drowning or decompression sickness following deep dives. Inspections and maintenance work in the splash zone, the part of the offshore structure immediately above and below the waterline, also pose serious hazards to divers. Strong winds, currents, and large waves affect diving safety. In the North Sea, although partially sheltered from the Atlantic by Britain, wave heights can reach 10-15 meters or higher. But even 2-meter waves, or currents alone, can cause crush injuries when diving in confined spaces. Underwater entanglement, or marine vessel impact, can also cause serious injuries to divers.

OceanTech offers a range of tools and techniques, ranging from lightweight robotic solutions to more heavy-duty solutions with industrial standard robotic arms. All tools and techniques are designed to avoid any use of divers or support vessels, improving operational safety significantly. There is no manual handling, which would be required when using divers, and our splash zone tools allow unmanned working close to structures in the harsh splash zone environment. Our splash zone tooling also provides a stable platform that enables the deployment of sensors, cameras, probes, and other inspection tools, which would have been impossible using divers.

Significant cost savings

Safety concerns aside, using divers in splash zone operations is also expensive. Safety concerns aside, using divers in splash zone operations is also expensive. Although rates vary significantly across continents, offshore divers require a large team topside, with support vessels frequently carrying more than 50 project personnel on board. This includes divers, supervisors, technicians, ROV pilots, survey teams, client personnel, vessel crew, and others. As the scope of a task grows, so does the size of the team – as well as the cost of operation. In the North Sea, the total cost for an offshore diving operation could easily exceed EUR 100,000 per day.

A considerable proportion of the vessels in use in the North Sea are also aging and have proven to be expensive to maintain. In recent years, largely driven by the rise in oil prices, the increased demand for support vessels is pushing prices higher.

Compared to using divers, OceanTech’s approach results in superior cost savings. In an Ekofisk oil field pilot, our solutions managed to achieve total savings of EUR 1.9 million for ConocoPhillips in a single year. The Exploration & Production company had previously relied on divers. Our use of splash zone tools achieves 100% coverage internally or externally and does not require any assistance from divers, ROVs, or support vessels. The cost savings are not least due to reduced man-hours. Our robotic solutions for remote cleaning, inspection, and maintenance only require a team of 3 to 5 persons. You also avoid lengthy and costly waits due to unpredictable weather. Divers only working in the water for a couple of hours, together with the normal diver window of just a few days, leads to work completion is highly dependent on favorable weather conditions. 

The cost savings are even greater in the aquaculture industry, where businesses rely on far more frequent inspections of nets, barges, and structures. As the industry moves further and further from shore, we have the technology and expertise required to help businesses complete work in a cost-effective manner.

Reduced carbon emissions

Global attention around carbon emissions is driving major offshore companies to look at how COreleases can be reduced in production, power generation, and operations. This has been demonstrated by major companies such as Equinor, which has issued plans to cut carbon intensity in half by 2050, and Lundin Energy (formerly known as Lundin Petroleum) announced carbon neutral targets, and a name change to remove the «petroleum» reference to reflect the industry’s energy transition. Another oil and gas supermajor, BP, has also set out its ambition to become a net zero company by 2050 or sooner. 

As offshore companies look to reduce emissions from their supply chains, our technology could become part of the solution. Offshore support vessels can output thousands of tonnes of CO2 every year, as well as significant amounts of nitrogen oxides (NOx) and sulfur oxides (SOx). With OceanTech, all splash zone tools are launched from the structure itself, minimizing the need for support vessels. This enables companies in offshore oil and gas, as well as in the offshore fish farming and offshore wind industry, to cut CO2 emissions from operations significantly.

As techniques and solutions for splash zone operations continue to evolve, industry professionals are asking themselves whether to use divers or robotic solutions. While the question may be simple, the answer depends on a multitude of factors including the scope of the task, local marine environment, and project complexity. Ultimately though, everything boils down to safety, cost, and carbon footprint.

Our track record includes successful operations in the North Sea, the Gulf of Mexico, and Australia. Our team of engineers and technicians constantly seek new and innovative ways of working, to maintain OceanTech’s position as the preferred supplier of underwater splash zone tooling on a global scale.

Robotic solutions vs. ROVs in the splash zone

Robotic solutions vs. ROVs in splash zone operations

ROVs may perform better at greater depths, but in the splash zone, OceanTech’s robotic solutions offer a wide range of benefits for businesses performing underwater cleaning, inspections, and maintenance work.Read more

What is the splash zone?

The splash zone is frequently defined as a non-accessible area and poses significant challenges to operations in offshore wind, oil and gas, fish farming, and transport infrastructure. But what exactly is the splash zone? And what are the challenges in splash zone operations?

In areas with harsh environments, such as in the North Sea, it is common to assume that offshore structures located in the splash zone are not easily accessible for cleaning, inspection, repair, or modification. In fact, the world’s largest classification society, DNV, describes the splash zone as a non-accessible area.

But what exactly is the splash zone?

DNVs Offshore Standard DNV-OS-C101 provides greater detail:

«The splash zone is the part of a support structure that is intermittently exposed to seawater due to the action of tides or waves. The splash zone separates the atmospheric zone and the submerged zone, and is determined by the influence of waves, tidal variations, settlements, subsidence, and vertical motions.»

At OceanTech, we define the splash zone as the part of the structure immediately above (+20 feet) and below (-50 feet) the waterline. The condition and integrity of offshore structures in the splash zone are affected by corrosion, fatigue, and marine growth.

Corrosion, fatigue, and marine growth 

The splash zone is not only a major challenge in the offshore oil and gas industry; underwater structures in offshore fish farming, offshore wind, and transport infrastructure, are also located in harsh marine environments. Steel structures, mooring systems, pipes, risers, fish farming nets, and monopiles are all exposed to aerated seawater, UV radiation, and repeated wetting and drying.

If left unchecked, the conditions in the splash zone can result in various serious problems, including:

  • Accelerated corrosion on exposed surfaces
  • Accelerated material strength fatigue
  • Marine growth, such as algae and mussels, in some cases up to three feet thick

The potential for a neglected problem to turn into an expensive issue is considerable. In offshore oil and gas, for example, plant failure and unplanned maintenance account for nearly half of overall efficiency losses. The notoriously unpredictable splash zone, however, poses real challenges for those involved in the cleaning, inspection, repair or modification of offshore assets.

Challenges in splash zone operations

Waves and structure-induced currents are ever-changing but always present in the splash zone, making it difficult for divers and remotely operated underwater vehicles (ROVs) to perform inspections and maintenance work. Although a significant proportion of structures are aging and in urgent need of inspection, splash zone operations are often perceived as too complex, too costly, or too hazardous.


Unlike deep-water environments, where divers and ROVs can function relatively undisturbed, the dynamic splash zone presents a number of specific hazards to both humans and technology. Variations in weather conditions, in particular, combined with the proliferation of pipework in the splash zone, create unpredictable circumstances for divers and ROVs.


 Traditional splash zone operations using divers and ROVs may be both time-consuming and costly. The normal diver window is only a few days, and work is highly dependent on favourable weather conditions. This means that the estimated costs of a work scope can increase significantly. There are also direct costs involved. Splash zone maintenance and repair has traditionally required the use of a diver support vessel at an approximate cost of EUR 180,000 per day.


 The difficulties presented in this environment can often make it too dangerous to work using traditional methods, such as rope access and diving. While working in confined spaces, crush injuries are always a risk, and the swell can disturb buoyancy and make it difficult to hold an exact position while working. 


 Offshore energy companies need to adhere to regulations, as well as design and operational standards. Environmental regulations, in particular, are becoming increasingly important. Non-compliance with laws and regulations can lead to heavy fines and possibly further complications. Owners of splash zone areas thus have a huge responsibility to ensure that equipment is maintained in accordance with the regulations.

OceanTech’s splash zone tools 

 What we are seeing is that the offshore wind, oil and gas, and fish farming industries are increasingly focused on finding alternative solutions to traditional methods. At OceanTech, we offer a wide range of innovative tools and techniques, from lightweight robotic solutions to more heavy-duty solutions with industrial standard robotic arms. All the tools and techniques are designed to avoid any use of divers, ROVs, or support vessels. 

The technology is developed for all underwater cleaning, inspection, repair, and modification services, and can be launched from any offshore structure. Our capabilities include:

  • Remotely operated robotic solutions for the cleaning of marine growth, or the removal of corrosion prior to inspection or repair
  • Visual and NDT services for the splash zone and underwater structures. Our robotic solutions provide a stable platform that enables the deployment of inspection tools which would be impossible using divers and ROVs
  • All repair solutions required in the splash zone, including corrosion protection, reinforcement, wrapping repair, and surface blasting
  • Modification services in the splash zone, including modifications of existing structures such as offshore platforms, bridge columns, port constructions, offshore wind turbines, and fish farming structures

Our services are often offered as a turn-key solution, and provide several benefits, including cost savings, efficiency and safety gains, reduced CO2 emissions, and regulatory compliance:

  • With no need for divers, ROVs, or support vessels, our innovative approach delivers superior cost savings in comparison to traditional methods
  • The technology is highly efficient and operates using all standard types of ROV subsea tooling. It offers great HSE benefits too, as there is no manual handling involved
  • Our robotic solutions are environmentally friendly, as they reduce CO2 emissions significantly by reducing the need for support vessels
  • We are familiar with both offshore regulations and requirements, in addition to design and operation standards. Our track record includes multiple operations in the North Sea, the Gulf of Mexico, and Australia

By utilizing OceanTech’s technology, the splash zone is no longer a non-accessible area.

The 8 most frequently asked questions about OceanTech

1. Are support vessels required during splash zone equipment installation or operation?

There is no need for support vessels such as diving support vessels, crane vessels, or remotely operated underwater vehicles (ROVs) during installation or operation. Our robotic solutions are installed from the platform and controlled from a purpose-built control unit on the topside of the platform.

All required splash zone tools and equipment are loaded on board the platform and installed by using advanced rigging techniques and skilled OceanTech rope access technicians. Common tools in our splash zone operations include vertical access tools, chain sleds, manipulator arms, mechanical tools, cutting tools, visual inspection tools, FMD systems, and HP water jet kits. 

2. Can your equipment be used at offshore wind farms or offshore fish farming operations

Yes, our tools and methods can be used in these marine structures, as well as monopiles, ship hulls, and concrete installations. As they are all exposed to wind forces, currents and waves, they will experience the same needs for inspection and maintenance over time. Our experience from splash zone interventions in the offshore oil & gas industry can easily be transferred to other installations, platforms, and structures.

3. What are the equipment and personnel (POB) requirements in splash zone operations?

The splash zone tools and equipment are generally lightweight and deployed from the platform using special rigging techniques. This means that small crews of three to six platform-based personnel can do work that expensive diving teams, or remotely operated underwater vehicles (ROVs), often struggle to complete. The OceanTech team generally consists of an offshore team leader, a splash zone pilot, rope access or subsea technician, and an inspection engineer if required. All our personnel has a proven track record of successfully operating our robotic solutions in the splash zone. In large-scale projects,  we have the capacity to deliver more robust teams of 25 upwards.

Our standard splash zone tools consist of three units: A Hydraulic Power Unit (HPU), a control cabin/suitcase, a container carrying lifting equipment, and the splash zone tools. All tools and techniques are developed in-house by a skilled engineering team with extensive field experience from offshore projects worldwide. Our Subsea Test Centre is an important contributor to the development of our innovative tools and full-scale testing. 

4. Do you require support from divers or ROVs?

All our splash zone tools and techniques are designed to avoid any use of divers and remotely operated underwater vehicles (ROVs). Our inspection capabilities, including cameras and other visual tools, provide a complete view of the underwater environment from the control cabin. Also, as we utilize temporary lifting equipment topside, neither ROVs, divers nor crane vessels are required to guide the equipment into position. We can also handle heavy loads with our lifting equipment. Previous projects include handling of up to 60 tons using temporary rigging and lifting equipment.

Our skilled engineering team has extensive field experience in splash zone operations and is capable of handling all rigging and temporary lifting equipment. Further, all of our equipment is purpose-built for our lifting operations.

5. How do you secure your splash zone tools to ensure safe working conditions?

Safe operations rely on clear leadership, skilled personnel, the provision of adequate equipment, as well as well-established security procedures to maintain a safe working environment. At OceanTech, we always ensure that our operations are performed to the highest standards of safety. All of our tools are secured in temporary lifting equipment and attached to at least two lifting points. In addition, they are stabilized with hydraulic clamping units. During operations, the splash zone tools are remotely operated from a control unit topside (suitcase unit or control container). Complex operations are simulated at our Subsea Test Centre, where personnel is required to undergo training prior to operation.

The splash zone tools are verified and certified by Det Norske Veritas (DNV), ensuring reliability in the face of marine hazards, and satisfying the safety requirements laid down in the NORSOK standard Z-015. In projects beyond the Norwegian continental shelf, we follow local requirements and regulations.

6. Is there any need for assistance from the platform crew?

Our team is small and self-reliant, and most of our equipment is transported and installed by OceanTech personnel. We do however require support from a crane crew to assist us with lifting our tools over the side of the platform, and into our pre-installed rigging equipment. Once our splash zone tools are unloaded and installed, there is no need for further crane support during operation.

Our Hydraulic Power Unit (HPU) and control unit require electrical power from the platform. All other tools and equipment are installed and operated by OceanTech personnel. 

7. What is the maximum wave height (Hs) in which OceanTech can perform splash zone operations?

Once our robotic solutions are deployed in the splash zone, we can perform cleaning, inspections, repair work, and modification services in wave heights up to 3 meters (Hs). The fact that we are able to work in these conditions provides us with a longer weather window than what is common using conventional methods.

Variations in weather conditions, particularly in harsh marine environments like the North Sea, create unpredictable weather windows for remotely operated underwater vehicles (ROVs) and divers. As divers can only work in the water for a couple of hours and need to perform the work in just a few days, work completion is highly dependent on favorable weather conditions. 

Our splash zone tools are not affected by waves and currents and enable us to perform work throughout the summer without costly delays.

8. What is your equipment mobilization time?

Depending on project complexity, we can mobilize our splash zone tools onshore in two to eight weeks. The tools are then safely transported to the platform, or other floating structure, in offshore containers. When the tools are unloaded offshore, we generally use somewhere between one to four shifts to prepare our tools. The time depends on the number of air hoists to be installed under the deck.

As all of our splash zone toolings are rigorously tested onshore at our Subsea Test Centre in Trondheim, Norway, the preparation and installation process offshore is generally quick and efficient.

How OceanTech uses robot technology for splash zone interventions

For many years now, oil and gas operators and service companies have been performing routine subsea interventions at depths of hundreds of meters and well interventions at depths of thousands of meters.Read more