Designing Cable Laying Vessels

We are dedicated to providing designs for cost-efficient vessel operations, taking into account safety, the comfort of the crew and the efficiency of operations. We advance the industry and reduce investment risks with our cable laying portfolio. We provide service and support throughout the lifecycle of the vessel.

What is a cable-laying vessel?

The purpose of a cable laying vessel is to lay underwater cables on the seabed to establish communication and networking between offshore structures or between areas and continents of the world. There are different types of cables, either for telecommunication or for electric power transmissions, with different usability, size and characteristics and to be laid at different sea depths and in different ground conditions. Cables can be laid directly on the seabed, buried by plough or trencher or covered by rocks. All this considered, understanding the specific operation and operation area of the ship to be designed is crucial.

When developing a design for a cable layer, important design criteria are capacities, functionality, and efficiency. Efficient laying of the cable, not compromising the gentle handling of the different cable types, is the main key to making a good Cable Laying vessel.

The specific requirements for each project will lead to a setup of cable equipment, around which the vessel layout is designed. To design a competitive, highly efficient cable layer, close cooperation is crucial between the design team and the owner, cable lay equipment vendor and other equipment suppliers to ensure the right choice of compromises from a technical- operational and financial perspective.

Our cable-laying vessel designs

Our fuel-efficient cable lay designs cover all cable installation projects, including power and fibre optic telecom cable, inter-array, export and interconnector cable laying. The fully integrated cable lay configuration is tailored to the owner’s requirements.

With an ULSTEIN X-BOW® Cable Laying Vessel, the vessel motions will be reduced and, consequently, also the strain on the cable. This might allow operations in worse weather conditions than a vessel with a conventional bow. Due to the absence of whipping movements in the ship, there will be less wear and tear of the cable. The X-BOW maintains its efficiency over a wide draught range from lightship to fully loaded, which is of high importance for a cable laying vessel. The X-BOW also minimises the accelerations, leading to smoother motions and a reduction in fuel consumption in waves.

Due to the precision requirements of the cable route, modern cable laying vessels need a dynamic position system. A smart and efficient system set-up is key to ensuring low fuel consumption and reduced cost and environmental footprint.


How do we contribute to the development of a cable-laying vessel?

Ulstein provides services and support in various steps and extent throughout the lifecycle of a cable lay vessel. From support in the development of the business case throughout ship design, engineering, integration and construction, power and main equipment integration, electrical services, site follow-up and turnkey shipbuilding deliveries. For sailing vessels, we offer life cycle services of different types and extent, from analysis and feasibility studies to retrofit and conversions.

Stages in the life of an offshore wind farm.


Shipyard for newbuilds and conversions

Our own shipyard, Ulstein Verft, is renowned for high-quality and on-time deliveries and has a proven track record in the construction of Cable Laying Vessels.

The latest cable layer newbuild from Ulstein Verft, the 'Nexans Aurora', an on-time delivery in 2021. (Fotograf Hagen)
The latest cable layer newbuild from Ulstein Verft, the 'Nexans Aurora', an on-time delivery in 2021. (Fotograf Hagen)

The future cable laying industry

The offshore wind industry is growing rapidly, and more cable-laying vessels will be needed in the years to come. Different operations will require different ship capacities, different equipment, layout and logistics.

Subsea cables are being laid at greater depths and are becoming longer, larger and heavier. There is also a need to replace cables that are damaged or obsolete due to maintenance costs. An essential design element is to protect the cables during operation and after the completion of the operation. The long-term reliability of the cables can be secured by the safe burial of the cables, deep enough to avoid any damage caused by anchors, trawling or other subsea activity. In addition to our series of cable laying vessels, Ulstein also has a proven track record of rock installation vessels for cable protection.

Our cable laying designs range from large, shallow-water, high cable-capacity workhorses to nimble and time-efficient cable repair vessels. These include designs for all cable installation projects, including vessels for power and telecom fibre optic, inter-array, export and interconnector cable laying.

Overview of CLV types:

Export cable laying vessels
Export cable laying vessels

Export cable laying vessels

Export cable laying vessels are used in offshore wind fields to connect the offshore grid to the shore network. The offshore wind farms are established further offshore, and the wind turbines and offshore wind farms are increasing in size. This means, that the export cables are also increasing in size and in length.

Export cable
Inter-array cable laying vessels
Inter-array cable laying vessels

Inter-array cable laying vessels

The inter-turbine (array) cable laying vessels are operating in-field at the offshore wind farms, laying power cable between the wind turbines. The cables are typically installed in single lengths from one turbine to the next. In general, wind turbines are increasing, which means that the cable size is also increasing.

Inter-array cable
Fibre optic cable laying vessels
Fibre optic cable laying vessels

Fibre optic cable laying vessels

The fibre cable vessels are typically working between continents, connecting the grids and laying long stretches of subsea cables. They are powerful, with high capacity, and particular care is taken in the design process to maintain low fuel consumption even in the most power-demanding situations.

Fibre-optic cable

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