The cast iron shells of the FMGC IBOCS project leave SEM-REV after almost 4 years at sea

The cast iron shells of the IBOCS project developed by FMGC to ballast submarine electrical cables have been successfully removed from the SEM-REV test site! They were immersed on site for 3½ years, with regular monitoring throughout the experiment within the European FORESEA and OCEAN DEMO programmes. We take a look back at this experiment!

on April 26, 2022

The IBOCS project was designed to test the stability of power cables ballasted with cast iron shells during winter storms. To do this, three sections of cable were installed in a row, equipped with shells of different weights, including an unshelled portion for comparison.

Throughout the 3-year immersion period, we were able to observe the stability of our cable protection shells during the various monitoring sessions. The monitoring results show strong cable stability, even under difficult storm conditions. This stability is also reflected in the very good cable protection, especially with regard to minimum bend radius - FMGC.

In addition, the project aimed to measure biocolonisation and corrosion of the submerged shells and to gain unique feedback in an environment representative of offshore wind farm conditions.

Colonisation was quite extensive on the exposed parts of the shells, but this had no impact on stability or their life span and even inhibited corrosion. Analysis of the recovered shells has allowed us to refine our corrosion models, which means that we can us ensure a long service life with optimal cable protection - FMGC.

All the test equipment was successfully dismantled by Atlantique Scaphandre, using their new Nanoplon vessel, even though certain portions of cable and their associated moorings were almost completely buried under the sea-bed.

This test was also an opportunity to use the SEM-ROV, acquired by the SEM-REV as part of a WEAMEC call for projects, which facilitated diving operations.

Photos: Centrale Nantes & FMGC
Published on May 4, 2022 Updated on October 19, 2023