Multi-Day Offshore USV Operations: Van Oord's Reality Check

What Happened

Van Oord’s unmanned survey vessel VO:X Barentsz has completed a multi-day autonomous survey at Ecowende’s Hollandse Kust West wind farm in the Dutch North Sea. It worked in conjunction with the three installation vessels Boreas, Link, and Subsea Viking, which installed monopylons and cables. This marks the first time an unmanned survey vessel specifically designed for offshore operations has successfully completed a multi-day mission at such a busy location. The VO:X Barentsz is Van Oord’s fifth unmanned survey vessel and the first adapted for offshore operations. Developed in collaboration with Demcon Unmanned Systems, it is based on the same platform as Van Oord’s older unmanned offshore survey vessels but boasts enhanced offshore capabilities – according to the manufacturer. It can operate for weeks at a time and perform a wide range of tasks, from dredging and wind turbine installation to the construction of offshore infrastructure. John van der Marel, project manager for unmanned surface vehicles at Van Oord, explains that this deployment demonstrates how unmanned vehicles can “operate remotely for days, deliver high-quality data, and further advance innovation in marine surveying.” Okay, but does this really promote innovation, or is it simply a way to save money by reducing the number of operators and surveyors? There are no shortcuts here. We’re rather skeptical.

Why This Matters

Unmanned surface vehicles (USVs) have long been used for offshore surveying. Coastal surveys, bathymetry – we’re familiar with that. However, few are deployed at sea for several days at a time, especially near construction sites. Even fewer provide reliable data for construction crews inspecting piles and laying cables – and that’s precisely the problem. Why are they so popular? Because they’re no longer just demonstrating their capabilities, but actually integrating these operations into offshore work. Wind farm schedules are relentless. Installers work within weather windows of just a few hours. Survey data is crucial: for the correct installation of monopiles, the prevention of erosion, and cable laying. If your drone delays work by two days because clients don’t trust your data, you can forget about the contract. “Several weeks” of work – we thoroughly investigate that claim. Offshore work isn’t just about long stints on the coast. Weather, traffic, communication – everything is different. A drone left unattended in the North Sea for five days? This solves entirely different problems than an eight-hour shift at the port. Where is the turning point? Which supervisory model delivers on the promises made by marketing? Reality demands a change of thinking.

The Reality on Deck

Multi-day offshore operations with unmanned surface vehicles (USVs) present challenges not encountered in coastal testing. Let’s start with positioning: GNSS is excellent when it works. Multipath reception near installation vessels, atmospheric delays as weather fronts pass through the North Sea, and variations in satellite geometry significantly impact accuracy. A manned survey vessel can typically manage this with the help of auxiliary systems, adjusting survey lines or even taking a weather break – but what about your drone? Either it has redundancy and intelligent decision logic, or you’ll end up with low-quality data that goes undetected for days. Verifying data quality is even more demanding. We’re talking about surveys to IHO S-44 Order 1a, the standard for offshore wind energy, which requires a depth accuracy of 0.5 ± 5m + 1.3% at a 95% confidence level. Manned vessels employ specialists who monitor echograms in real time, identify problems, and spontaneously reconfigure lines. With a remotely operated unmanned surface vehicle (UUV), you’re reliant on automated checks and human error. If the surface sound velocity measurement is distorted, backscatter occurs, or positioning is disrupted, detection depends on who is monitoring the measurements – if anyone is. And who can interrupt the measurements or alter the results? The weather? Uncertainty abounds. Installation vessels typically suspend operations at Beaufort State force 6 or significant wave heights above 5m. Their smaller UUVs can withstand harsher conditions – less freeboard, no personnel safety concerns. Sounds good, right? Well, not quite – you have a serious coordination problem. If your installation team is on standby due to weather, the measurement data remains unused until the installation resumes. That’s a truly critical issue. But your UAV is at sea, consuming batteries and requiring remote monitoring by staff who should be on break. This is no small matter; what appears to be an endurance advantage quickly turns into operational chaos. Communication range? It’s crucial. In the southern North Sea, 4G LTE works about 25–30 km offshore, but range decreases further north. Beyond this distance, satellite communication is out of the question. While VSAT offers sufficient bandwidth for real-time monitoring, it suffers from latency and high costs. Iridium covers the entire globe but lacks the necessary bandwidth for complete remote control. Starlink Maritime? It’s an interim solution and isn’t yet widely used in marine research. So the question isn’t whether your unmanned surface vehicle can operate for three weeks, but whether you can guarantee effective remote communication and data transmission over such a long period. And whether you can accept the high costs and latency.

Where Clients Get It Wrong

1. Assuming Lower Cost Means Better Value

Sure, having a survey team on-site lowers daily rates, but it also increases other costs. Remote work requires personnel on land – at least one person to monitor multiple unmanned surface vehicles (UPVs) simultaneously (yes, really!), as well as specialists in survey management and data processing. In short, you need a reliable communications infrastructure and backup positioning, because troubleshooting remotely isn’t easy – and we mustn’t forget high-quality batteries and chargers. Insurance for autonomous operations? Good luck finding an insurer that will cover that. The cost-benefit ratio depends on the project duration. For continuous, repetitive surveys, such as short cable runs, UAVs might be suitable, but for fast, dynamic tasks, such as a three-day emergency survey? A manned vessel saves time.

2. Confusing Endurance with Availability

Advertising constantly touts unmanned surface vehicles with weeks of autonomy – as if that were all there is to it – but in reality, operational availability is crucial. Even the most advanced UAVs can operate on batteries for weeks, but still require downtime due to weather, maintenance, and data downloads. Operating for just 18 hours a day and achieving 80% availability in all weather conditions, the effective operating time drops drastically to 14.4 hours. And a manned vessel? It can operate for 16 hours, achieving 95% availability in all weather conditions by adapting to conditions perceived by humans. A significant difference. This advantage adds up over several weeks. Then there’s the question of personnel. “Unmanned” doesn’t mean “unattended.” Someone has to monitor the data streams, analyze the data in real time, and manage communication with the UAV. No robot can replace the expertise of a surveyor. Finding qualified remote control operators is not just difficult – it is a real challenge compared to finding experienced surveying teams.

3. Overlooking Data Validation Workflows

What do construction crews need? As-built usable data. Surveys determine the positions of pile foundations, preliminary investigations map cable routes, and erosion studies authorize the introduction of aggregates. All of this requires verified data – and fast. Data collected by autonomous surface vehicles (USVs) often slows down this process. The vessel collects the data – someone downloads it, processes it, and verifies it. Quality control can uncover problems that lead to re-surveys. This delay, when surveyors aren’t directly behind the sonar, disrupts tight schedules and leaves installation vessels idle, waiting for approval.

4. Ignoring Liability and Certification Gaps

Who approves the survey data? When working with a team, the lead surveyor gives their stamp of approval to the results. Remote control is complete chaos: a remote monitor, a data processing team, a drone pilot? Just wait until a 5m error in a cable survey necessitates a complete remobilization. The rules are simple: there is no single standard. Classification societies offer recommendations (Lloyd’s Register, DNV), but most drones lack full maritime certification. And then there’s insurance. Coverage for commercial autonomous surveys is limited, if it exists at all. Some insurers exclude autonomous options entirely, while others impose so many restrictions that the benefits of extended coverage are purely theoretical. Ignoring certification and insurance means you’ll have to find a solution quickly in an emergency.

What Actually Determines Success

For unmanned surface vehicles to operate effectively on the open sea, let’s be realistic: reliable equipment alone isn’t enough. It’s essential to meet, or better yet, exceed the positioning redundancy standards of manned vessels. This means using SBAS-corrected GNSS as the primary system, with RTK as a backup where range allows. Don’t forget acoustic positioning for operations in close proximity to platforms. And a tactical IMU is crucial to minimize troublesome GNSS outages. The reality is this: you can’t just send someone on a mission when the receiver loses signal – that’s far from ideal. Communication architecture is now the foundation of operational effectiveness. You need at least dual-channel communication: for example, 4G LTE with a backup satellite link. You need bandwidth that enables real-time bathymetry, not just vessel tracking. The latency for control signals must be less than two seconds. And upload all data during weather-related downtime, when bandwidth costs are secondary to meeting the schedule. Clearly define the remote monitoring protocols before work begins. The following is crucial: Who monitors the unmanned surface vehicle (UPV) during night operations? What triggers immediate action, rather than a “we’ll check it tomorrow” approach? Who decides to change survey parameters or even abort the mission? And what exactly is reviewed after data processing? Customers who treat these questions as mere operational details often find themselves in disputes. Let’s talk about bad weather procedures. If you assume that both the drone and the support vessel will halt operations when the weather deteriorates, you haven’t considered asymmetric operations. Define the conditions under which the drone will continue flying while the support vessel waits. Consider how you will handle data from surveys conducted without the involvement of the installation crew. And clarify liability in case the bad weather worsens than predicted – such incidents are not uncommon in the North Sea. Clarify these issues, and you will avoid future chaos.

The Path Forward

Van Oord’s multi-day deployment proves that the use of unmanned surface vehicles (USVs) is technically feasible. However, it is more difficult to determine where they actually add value and not just create additional problems. Survey managers must align the use of UAVs with real operational needs and not be guided by technological promises. UAVs are excellent for planned survey work with stable positioning – for example, monitoring cable routes, supporting construction work in calm waters, and conducting basic infrastructure inspections. Here, survey plans remain stable, data verification can be performed routinely, and clients can tolerate delays in data delivery. However, for complex survey work requiring rapid adjustments, operation in densely populated areas, or adherence to deadlines, manned vessels remain the best option. Human decision-making is superior to autonomous systems when plans don’t go as expected. The problem: We receive very little operational data for long-term campaigns. What is the availability over several weeks? How many survey lines need to be redone due to positioning errors? Is data verification slower than with a crew? What are the true costs, including shore support, communications, and insurance? Without reliable performance data from operators, customers face significant challenges when making purchasing decisions. Van Oord’s implementation of the VO:X Barentsz system is a step forward. But the next big step isn’t just about more demanding conditions or longer missions. It’s about delivering clear reports on what worked, what didn’t, and where the true limits lie. In the offshore industry, new technologies only remain relevant if they truly solve problems. Prove your reliability first – success will follow.

Based on: Van Oord completes first multi-day offshore deployment with VO:X Barentsz