Preparing Milford Haven for floating offshore wind

Floating offshore wind is expected to play a major role in delivering low‑carbon energy in the Celtic Sea, with turbines ranging from 15-20 megawatts (MW). These structures are significantly larger and more complex than vessels and floating assets traditionally handled at Milford Haven.

The Port of Milford Haven needed clarity on whether partially assembled and fully integrated floating offshore wind turbines could be safely towed, manoeuvred, moored and exported through an estuary characterised by strong tidal currents, constrained turning areas and limited under keel clearance.

There was a strong need for independent, evidence‑based advice to understand operational limits, environmental constraints and risks, while ensuring future turbine movements would not compromise existing shipping, port infrastructure or cargo operations. This understanding was critical to inform early planning, infrastructure readiness and long‑term investment decisions.

We carried out a high‑level navigation and towage assessment to help the Port determine whether practical and safe operating concepts could be developed for a range of floating offshore wind substructures.

Our approach considered both unintegrated substructures and fully assembled 15-20 MW turbines, including steel semi‑submersibles, concrete barges and tension‑leg platforms. We assessed towing operations in both directions within the Haven, transits on semi‑submersible vessels, and options for temporary mooring.

Each activity was evaluated against what mattered most to the Port: whether operations could be resilient to wind and tidal conditions, compatible with existing traffic and infrastructure, and achievable within the physical constraints of the estuary. We reviewed established towage practices for large floating assets alongside emerging handling and manoeuvring techniques suited to floating offshore wind.

Given the unusual hydrodynamic behaviour of fully assembled turbines, we recommended further modelling capable of representing six degrees of freedom, supported by physical modelling to assess stability in currents and during constrained manoeuvres. This was combined with HR Wallingford’s phased navigation simulation methodology, providing a clear framework for progressively reducing uncertainty.

Key considerations included tidal windows, combined wind and current effects, air draught and under keel clearance, tow controllability, minimum towage requirements, environmental data needs and the scope of future navigation risk assessments.

The assessment provided the Port of Milford Haven with a robust foundation to inform its potential role in supporting floating offshore wind deployment and maintenance in the Celtic Sea.

While further detailed navigation risk assessments and operational planning are required, the study confirmed that safe and practical towing concepts could be developed for both floating substructures and fully integrated turbines. By identifying constraints, risks and data needs at an early stage, the work reduced uncertainty for stakeholders and supported more resilient, sustainable planning.

In the longer term, improving the feasibility of floating offshore wind operations helps accelerate low‑carbon energy production, strengthen regional supply chains and position Milford Haven as a strategically important hub in the UK’s transition to net zero.