Break-through in the tidal energy sector.


GeoSea: Use of jack-up vessels under extreme tidal conditions demonstrated.

RAZ BLANCHARD, FRANCE: As a specialist in complex offshore marine engineering projects, GeoSea (DEME Group) has successfully completed trials of a jack-up vessel in extreme current flows. The results of the trials confute industry reluctance to deploy jack-up vessels on tidal sites. The demonstrated workability and reliability create confidence for tidal project developers and open the market for all types of tidal energy

GeoSea has chosen the French Raz Blanchard as its operational area, a renowned site for strong tidal currents, located between Alderney (UK) and Cap de la Hague (FR). The campaign was held during the Autumnal Equinox of September 2015 with currents during spring peaks. GeoSea’s jack-up vessel Goliath operated in currents of up to 10 knots (approx. 5 m/s) and water depths, under hull, of 56 meters.

The demonstrated utilisation of GeoSea’s jack-up platform under those extreme tidal conditions are the direct result and the practical implementation of a two year in-house study analysing and researching the behaviour of jack-up platforms while jacked-up in strong currents. On that basis, specific operating models as well as procedural and technical improvements have been developed that enable the use of the  GeoSea’s respective jack-up platforms and vessels in strong tidal race areas.

The real life trials at Raz Blanchard validated and calibrated those models and procedures with a successful result: GeoSea’s jack-ups are able to position accurately and to operate safely in tidal sites, even in those sites that are recognised as one the most extreme and energetic with significant depths.

This is an important milestone in the tidal energy sector which will accelerate the construction of tidal turbines and all related operations such as maintenance and decommissioning. GeoSea’s practical experiences under those demonstrated extreme conditions should give confidence to developers and project owners alike to use cost effective jack-up platforms and vessels for the realization of their tidal projects.



To see a video of the demonstration campaign, click here.

More information
Marleen Vanhecke
Head of Communication at DEME Group
M + 32 486 49 01 09