Offshore Construction

Princess Elisabeth's 23rd caisson closes the ring, not the grid programme

Published 20 August 2026 Publisher IMWO Region Europe Confidence Confirmed
Princess Elisabeth Island delivery-sequence graphic separating 23 caissons completed at the yard, an installed offshore perimeter, and later sand reclamation and electrical delivery

Graphic: IMWO, based on Jan De Nul, DEME and Elia records; milestone diagram, not a site photograph or scaled island layout

TM EDISON has installed the final caisson at Princess Elisabeth Island, completing the 23-element protective perimeter in the Belgian North Sea. Jan De Nul's 20 August account advances the project beyond January's yard-completion milestone. The change opens the next marine-construction phase; it does not mean the island is ready to export electricity.

January fabrication and August installation are separate milestones

DEME's 29 January announcement concerned the final caisson's construction and flotation at Vlissingen, with finishing work and offshore installation remaining. August's contractor account instead reports the complete foundation ring at sea. The distinction matters for progress comparisons: the same element can be fabricated, floated, stored, transported and installed on different dates.

Reclamation shifts the interfaces from heavy units to an island platform

The original Elia EPCI award separates island design and construction from later high-voltage infrastructure. DEME's 2024 construction description connects the caisson perimeter to sand filling and an eventual platform for electrical equipment. Once the ring is installed, fill placement, drainage, platform levels and handover conditions become the critical connection between marine and electrical packages. A completed structural shell does not remove those interfaces.

Evidence conclusion

Electrical readiness follows later acceptance stages

The August update gives a reported sequence of sand reclamation, mainland cables in 2027-2028, electrical installation from 2029 and completion planned for 2031. These dates are forward programme statements. Foundation installation and electrical readiness need separate acceptance records: perimeter geometry and integrity, suitable fill and platform handover, followed by equipment and cable testing. The 2023 construction programme is an earlier baseline, not a current first-power date. August's installation milestone should not be counted twice by treating January's yard achievement as the same field result.

Outstanding evidence

  • Sand placement and platform handover criteria
  • Foundation geometry and integrity acceptance
  • Marine access during electrical construction
  • Cable and electrical-package delivery against the revised programme

Related records 1

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