How Deep Should We Bury Offshore Cables? Insights from Physical and Numerical Modelling
Offshore wind is now central to the UK’s economy and energy security, but some elements of the supporting infrastructure remain persistently vulnerable. Subsea power cables, the assets that transport electricity from offshore turbines to the onshore grid, are responsible for around 75% of the cost of all insurance claims, and individual faults routinely take 100+ days to repair. Each failure interrupts power supply, reduces revenue, and ultimately lengthens payback periods, constraining investment across the sector. Recent analysis shows that around 70% of cable damage arises from accidental interaction with anchors and fishing gear, with deliberate interference and grey‑zone activity emerging as additional risks.
The primary defense is burial: lowering the cable beneath the seabed to reduce the likelihood of anchor penetration. The required burial depth, specified through the Cable Burial Risk Assessment (CBRA) process, must balance two competing pressures; the economic cost of deeper burial operations and the risk of anchor strike in busy marine environments. The UK’s planned expansion of offshore wind, a 7.5‑fold increase in installed capacity over the next 30 years, will require extensive new cable routes through some of the world’s most congested shipping and fishing corridors. Ensuring that these cables are buried at an appropriate depth is therefore essential. Yet current CBRA guidance provides limited direction on how varying seabed conditions influence anchor penetration, particularly in layered soils.
This gap is being addressed through a collaborative research programme between Durham University, the University of Dundee, and the British Geological Survey: Offshore Cable Burial: How deep is deep enough? This seminar will present key findings from the project’s physical modelling and advanced numerical simulations, highlighting the influence of seabed conditions, anchor size, and soil layering on penetration behaviour. The results provide new evidence and datasets to support the next generation of CBRA methodologies and more reliable, site‑specific burial recommendations.
Presenter: Prof Will Coombs, Durham University