Altera nearing completion: A new generation Cable Maintenance Vessel for N-Sea

Recently, the Groot Ship Design team visited Neptune Shipyard in Hardinxveld, where the new cable maintenance vessel (CMV) Altera for N-Sea is nearing completion.

Designed for cable laying and maintenance operations in coastal and shallow-water environments, Altera is a versatile offshore support vessel equipped with dynamic positioning capabilities and a six-point anchoring system.

With an overall length of 99.9 metres, a beam of 28 metres and a maximum draught of just 5 metres, Altera offers deadweight capacity of 7,400 tonnes and an impressive 1,800 m² of working deck space. Two deck cranes with lifting capacities of 25 and 8.5 tonnes support a wide range of offshore operations.

The vessel provides accommodation for up to 100 personnel under SPS notation, ensuring comfort and operational efficiency during extended offshore missions. Propulsion is provided by a fully diesel-electric system, featuring two azimuth thrusters aft, two bow thrusters and two retractable thrusters, delivering a total installed thruster power of 7,900 kW.

Originally conceived as a fully methanol-fuelled vessel, Altera will initially be delivered as methanol-ready, enabling a smooth transition towards more sustainable operations in the future.

Groot Ship Design was contracted for the design verification, detailed design, as well as the basic and detail engineering of the vessel. The project represented an extensive engineering effort spanning around two years.

Throughout the design process, numerous technical challenges were successfully addressed. Topics such as damage stability, structural optimisation and the integration of demanding operational requirements required close cooperation between all project partners. The vessel's voluminous methanol tanks and -systems including cofferdams, large consumable storage capacities, extensive HVAC and sewage systems for 100 personnel, retractable thrusters, anchoring equipment and electrical installations all competed for valuable onboard space. Bringing these requirements together into a practical, efficient and fully approved design required significant engineering expertise and dedication.

The combined efforts of all parties involved have resulted in an impressive vessel that is now entering its final stages before delivery. For Groot Ship Design, only the inclining test and completion of the final documentation remain.

We would like to compliment Neptune Shipyard on this remarkable achievement and thank all project partners for the excellent cooperation throughout the project. We wish N-Sea, the future crew and everyone involved a successful delivery and many safe and successful operations with Altera in the years ahead.