The Fécamp offshore wind foundations from Eiffage S.A. - heavy steel, tight tolerances and a North Sea stress test

Reviewed: ad hoc news Classics & Longseller desk. Edited and checked on 2026-06-29, 09:45. Details in the imprint.

Fécamp offshore wind foundations from Eiffage S.A. rise from the grey water off Normandy like a row of steel giants, streaked with salt spray and the dull thud of waves against metal. You feel the vibration through the boat deck as each jacket takes the load of a 6 MW turbine.

How the foundations are built

The Fécamp offshore wind project uses lattice steel jacket foundations, fabricated and assembled by Eiffage’s metal division for a field of 71 Siemens Gamesa turbines in the English Channel. Each jacket stands roughly 50 to 60 meters high from seabed to waterline and weighs hundreds of tons.

Project director Jean-François Ropert describes the workflow in almost rhythmic terms: cutting plate, welding nodes, blasting, painting, then shipping the completed jackets from the Normandy coast onto heavy-lift barges. The shop floor smells of hot steel and paint, and the air rings with grinder noise.

Design choices for rough seas

Compared to simple monopiles, these Fécamp foundations rely on four-legged jackets pinned into pre-drilled piles, chosen for the rocky seabed and water depths that push beyond the comfort zone of single-tube foundations. The open lattice lets waves pass through, reducing bending loads at the mudline.

Engineers at Eiffage tuned the geometry for fatigue, not just brute strength. Tubes are thicker near the joints, braces are triangulated, and critical welds go through ultrasonic inspection before any jacket leaves the yard. It is a very tidy response to decades of offshore oil experience now repurposed for wind.

Installation out on the water

Out at sea, each foundation arrives strapped to the deck of a heavy-lift vessel, painted in high-visibility yellow and still smelling faintly of solvent. Crane operator Marc Leclerc watches wind and wave windows, then lifts the jacket in one slow motion, lining up the four feet with pre-driven piles.

Crews work in tight two-hour shifts between weather fronts. They bolt and weld connection sleeves, grout annuli, and check elevations with laser rangefinders so the nacelles will sit level once the towers are stacked. Every millimeter counts when you are 13 kilometers offshore and maintenance trips are costly.

What the project delivers

The completed Fécamp wind farm is planned at around 500 MW of capacity, giving the jackets decades of service life under constant cycling from Atlantic weather. For a French grid increasingly hungry for low-carbon power, these foundations quietly anchor a sizeable slice of annual production in steel and concrete.

From an operations point of view, the choice of jackets and careful corrosion protection should translate into reduced unplanned interventions. Operators can focus maintenance on the turbines themselves, while divers and ROVs handle periodic inspections of splash zones, brace intersections and pile heads.

Maintenance and fatigue management

Eiffage’s structural team has mapped inspection routes around each jacket, breaking the lattice into zones that can be checked on fixed cycles. Fatigue-critical joints get more frequent attention, while low-stress braces are logged with longer intervals to keep OPEX under control.

Surface crews can feel the foundations working. Standing on a transition piece during a winter swell, technicians report a subtle sway under their boots and the hollow echo as waves pass through the lattice. It is raw but controlled, a reminder that the sea never stops loading the entire structure.

Environmental and local impact

Below the surface, the jackets function as artificial reefs. Over time, mussels, algae and small fish colonise the steel, turning bare metal into textured habitat. Divers from the maintenance teams talk about the sharp contrast between the clean welds in year one and the fully encrusted braces a few seasons later.

Onshore, Eiffage’s workshops around Normandy and Brittany have hired welders, fitters and coating specialists who might previously have worked on bridges or viaducts. For local authorities, the foundations represent industrial continuity with a climate angle rather than a wholesale shift in skills.

How Fécamp fits into Eiffage’s portfolio

Fécamp sits alongside other marine and energy structures in Eiffage’s order book, from offshore substations to bridge piles. For CEO Benoît de Ruffray, the project shows how the group’s historic expertise in heavy civil engineering can be redeployed toward long-lived energy assets with predictable cash flows.

All told, Eiffage shares (ISIN FR0000130452) trade on Euronext Paris, and long-term contracts like Fécamp’s steel foundations help underpin the perception of the company as a steady infrastructure supplier rather than a short-cycle contractor.

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