FMGC Trials Ballast System for Subsea Cables at SEM-REV Site

FMGC has recently installed the cast iron shells (IBOCS) – developed to ballast subsea electrical cables – at a depth of 30 meters on the Centrale Nantes SEM-REV offshore test site.

These tests are part of the FORESEA project, which aims to help bring marine renewable energy (MRE) technologies to market by providing access to the North-European network of offshore test sites, which includes SEM-REV.

The FMGC shells protect, stabilize and restrict the bend of subsea electrical cables. The objective of the tests is to demonstrate the stability of the cables ballasted with these cast iron shells, including under heavy swell conditions.

The shells will remain on site for several months and will be subjected to extreme winter conditions. These tests will also provide comparative data, since three sections of test cables – two equipped with shells of different linear density and the third completely bare – were installed alongside each other.

The FMGC and SEM-REV teams will observe how the shells bear up (resistance, corrosion, etc.) in order to gain feedback in an environment representative of offshore wind farm conditions.

Innosea, a Centrale Nantes spin-off, worked with FMGC on shell design methods to calculate the optimal mass required to ensure cable stability on the sea floor. FMGC also equipped the Floatgen foundation – the first offshore wind turbine in France – with clump weights, which are attached to the anchor lines, providing stability to the floating structure.

The FMGC is the third company to make use of the Centrale Nantes offshore test site, following on from NEREIS Environnement’s acoustic sensor and the Floatgen floating wind turbine – a European research project involving Idéol, Bouygues TP and Centrale Nantes.

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