An offshore structure doesn’t become less of a hazard just because production has stopped. It’s still in the water, often within active shipping routes, and it still needs to be clearly marked for passing vessels. The responsibilities around Aids to Navigation continue throughout decommissioning and don’t drop away once operations end.
When permanent power is removed, the AtoN system has to operate independently. There’s no reliance on platform power, maintenance access is often reduced, and compliance requirements remain the same. Planning for this transition is a critical part of any decommissioning project, and it’s often underestimated.
Why AtoN Requirements Continue Throughout Decommissioning
Decommissioning doesn’t change the physical presence of a structure in the water. From a navigation perspective, the hazard remains. In some cases, it can even become less predictable as parts of the structure are removed or altered.
Regulatory requirements stay in place from the start of decommissioning until full removal. These requirements are based on the structure’s hazard classification, not whether it’s producing. In practice, that means the AtoN system still needs to meet the same standards for nominal range, flash character, and availability throughout the decommissioning programme.
For operators, this becomes an ongoing compliance responsibility that can last for several years.
What Changes When Permanent Power is Removed
During normal operations, AtoN equipment is supported by the platform’s main electrical supply. Lanterns, racon beacons, fog signals, and monitoring systems all rely on a stable, continuous power source.
Once that’s removed, the system has to run as a standalone setup. Solar generation and battery storage take over, with no fallback to platform power. Maintenance access is also likely to be less frequent.
This brings a different set of design considerations. Equipment that worked well during operations won’t always be suitable for long-term standalone use, especially in environments with limited daylight during winter months.
AtoN Equipment for Decommissioning Projects
A reliable AtoN system during decommissioning depends on multiple components working together to maintain visibility and identification.
Marine lanterns
Lanterns provide the primary visual marking of the structure. They need to maintain the required nominal range and flash character throughout the decommissioning period. In a standalone system, energy efficiency becomes more important, particularly where access for maintenance is limited. Orga marine lanterns are widely used in offshore environments and can be configured to meet the required marking standards while keeping power demand low.
Marine foghorns
In areas where visibility is frequently reduced, fog signals remain an important part of the marking system. They provide an audible warning when visual aids aren’t enough. Because they draw more power than most other AtoN equipment, they need to be carefully considered within the overall energy design. Tideland Signal supplies marine foghorns designed for offshore conditions, with reliable performance in harsh environments where a consistent audible warning is required.
Racon beacons and AIS
As decommissioning progresses, the structure’s physical profile can change. Racon beacons provide a clear radar return that allows vessels to accurately identify the structure. This becomes more important as the number of visual reference points decreases.
AIS equipment supports this by broadcasting the structure’s position directly to vessels. Together, these systems help ensure the structure can be identified across different navigation methods. Tideland Signal racon beacons provide coded radar responses that allow mariners to clearly identify and distinguish offshore structures on their navigation systems.
Visibility sensors
Visibility sensors allow fog signals to respond to actual conditions. Rather than running continuously, they activate when visibility drops below a set level. This helps manage energy use while still maintaining safety.
Designing a Standalone AtoN Power System
Moving to a solar and battery system requires careful planning. If the system is undersized, reliability becomes a risk. If it’s oversized, it adds unnecessary cost, weight, and installation complexity.
The starting point is understanding the total energy demand. That includes lantern output, operating cycles, racon and AIS usage, monitoring systems, and any fog signal requirements. Battery capacity should reflect realistic maintenance intervals, not ideal ones. Solar panels should be sized using worst-case seasonal conditions rather than annual averages.
In regions like the North Sea, winter performance matters. Systems designed using yearly averages can struggle during periods of low sunlight.
Remote Monitoring of AtoN Systems During Decommissioning
Decommissioning programmes can run for several years. During that time, AtoN systems need to operate reliably without frequent site visits. If something goes wrong, it needs to be picked up early to avoid compliance issues.
Remote monitoring allows operators to track battery levels, solar input, and equipment performance in real time. Alerts can flag potential issues before they affect the marking standard.
For operators managing multiple assets, this also gives a clearer view of system performance across different locations.
When to Review Your AtoN Setup
The best time to review AtoN provision is before decommissioning begins. At that stage, there’s time to assess whether existing equipment is suitable for standalone operation, identify any gaps, and make changes without affecting the wider project schedule.
This review should cover whether current equipment meets post-blackout requirements, whether the power system can be replaced effectively, whether battery autonomy matches maintenance access, and whether monitoring is in place. Addressing this early helps avoid reactive fixes later, which tend to increase costs and cause delays.
AtoN Support for Decommissioning Projects
At Wellhead Electrical Supplies, we work with offshore operators and contractors to support Aids to Navigation requirements during decommissioning.
We supply lanterns, racon beacons, fog signals, and standalone solar power systems designed for post-blackout operation. Alongside this, we provide technical input to make sure each system is correctly specified and aligned with regulatory requirements.
If you’re preparing for decommissioning or reviewing an existing setup, we can help you define what’s needed and source it efficiently.
Contact Wellhead Electrical Supplies to discuss your decommissioning project requirements.