From production to port

In June 2026, seven of the fourteen steel components that make up a TetraSub floating wind foundation left Welcon’s production facilities in Give, bound for the Port of Hvide Sande on the west coast of Jutland. They were the seven largest components: a centre column section of 509 tonnes, ballast tanks 12 metres in diameter, and radial tubes up to 54 metres.

The haulage was carried out by BMS Krangården, Torben Rafn A/S, and ST Følgebiler over two weeks, moving at night on public roads through western Jutland.

What makes the operation significant is the infrastructure it ran on: an existing steel and tower factory, public roads, and a regional port.

Floating foundations are conventionally built in large dry docks and specialised yards. TetraSub is designed for facilities that most industrial economies already have, and June was the first time that design was tested at full scale on a commercial foundation.

Videos: from the factory in Give to the ship at Hvide Sande

The components moved over the two-week window include a centre column section weighing 509 tonnes, ballast tanks 12 metres in diameter, and radial tubes up to 54 metres in length. See how it looked:

The route: Hvide Sande via Spain to Grenaa

Hvide Sande was the immediate destination, not the final one. From there the components were shipped to the port city of Aviles in Spain, where additional elements are mounted and surface treatment applied.

That work has to happen after the components leave Denmark by sea, because the outfitted assemblies exceed what Danish roads can take. Hvide Sande was chosen for exactly this reason: a port that could receive the road transports and handle the onward shipping.

The components return to Denmark in 2027 for final assembly at the quayside in the Port of Grenaa. Assembly is bolted, not welded, the components arrive finished and are joined using conventional land-based cranes. This is the part of the design philosophy the whole logistics chain exists to serve: manufacturing distributed across standard industrial facilities, converging at a port for rapid assembly.

The approach was verified through the TetraSpar Demonstrator, which operated with a 3.6 MW turbine at METCentre off Norway from 2021 to 2026. The TetraSub applies the same principles to a floating foundation designed for turbines in the 15+ MW class.

What it means for deepwater markets

Most of the world’s offshore wind potential lies in water deeper than 60 metres, where bottom-fixed foundations are not viable. Markets with steep coastal seabeds like Japan, South Korea, the US West Coast, parts of southern Europe, need floating foundations if they are to use offshore wind at all.

Much of what decides those markets is the supply chain: whether foundations can be built in volume, close to where they are needed, using yards that already exist.

Stiesdal Offshore’s modular TetraSub foundation changes what that supply chain has to look like:

• Production without dry docks. Components are engineered for standard steel and tower fabrication facilities.
• Transport on existing infrastructure. Individual modules move by road or sea to regional port hubs, as the June operation demonstrated.
• Assembly at conventional ports. Final assembly needs quayside space and cranes, not a specialised installation yard, and the finished foundation is towed to site without a heavy-lift vessel.

Together these mean foundations can be assembled and deployed regionally, securing fast project delivery and competitive cost levels.