1600hp Leviathan Storms the Sand Waves

Innovative subsea trenching contractor Aratellus today revealed its involvement in a significant new Offshore Wind project, and additional contract awards, for its Leviathan subsea trenching system.

Developed for the burial of export and inter-array cables in Offshore Wind, the unique, four-track configuration is designed to optimise performance in challenging seabeds and, in particular, the sand waves and megaripples increasingly encountered in offshore energy projects.  This capability, combined with ability to operate in either a cutting or jetting configuration, offers unrivalled flexibility in the delivery of offshore renewable projects.

In support of global cable installation contractor Seaway7, the modular Aratellus system has been operating throughout 2022 in Southeast Asia, where it has been providing trenching services onboard a locally flagged, DP3 construction vessel.

This was the first cable burial project for Leviathan, having previously been mobilised for its first offshore trenching projects in the Gulf of Mexico, in October 2020.

This first cable protection project with Seaway7 has seen the Leviathan system mobilise in South Korea, for its first project offshore Taiwan.  Undertaken in the challenging offshore conditions in the Formosa Strait, this project saw Leviathan triumph in substantial subsea currents as well as highly variable seabeds across the site – including the sand wave and mega ripple conditions for which it was designed.

Nigel Ward, Aratellus Managing Director, said “since the business was founded in 2020, Leviathan has been working in Mexico trenching large diameter pipelines.  We are delighted with this important award for the trenching of inter-array and export cables in the offshore wind industry, which is what the system was optimised to do. In particular, we are delighted to have been supporting Seaway7, one of the most experienced and respected EPCI Contractors in the Offshore Wind industry”. 

He continued, “the combination of high power (1,600hp) and the self-levelling four track system is ideal for challenging offshore wind conditions, including significant sand waves, whilst targeting deep burial.  Traditionally, two-tracked trenchers struggle in these conditions because they ‘tip’ over the top of the sand wave, or struggle for traction. The Leviathan system, conversely, enables graceful cresting, this ensures the product is kept safe and within design tolerances, but also provides a much-improved trench quality over incumbent solutions.  Systems like this greatly reduce the amount of seabed preparation required in advance of trenching, with substantial cost savings achieved as a result”.

Gary Nicoll, Offshore Manager Seaway7, said “The system has performed very well in the seabed conditions we have in this area. Having worked in the region for several years, the slopes and sand waves experienced are always challenging but the Leviathan has certainly managed to deal with that.

The 4 independent tracks and varying ride height, in my opinion, set it apart allowing it to trench while dealing with all manner of pitch/roll angles.  Experience and knowledge shown by the team offshore has been exemplary as has the support from their onshore team. It has been a pleasure to work with all at Aratellus.”

Andy Foster, Project Manager Seaway7, said “We knew that the challenging seabed conditions in the Taiwanese strait would require an innovative approach. The advertised capability of the Leviathan looked to be the ideal solution, as the conditions we would experience were the exact same conditions for which the machine had been designed and built, however there remained some unknowns over how the machine would actually perform. While we experienced some initial challenges we were reassured and impressed by the responsiveness, professionalism and genuine collaboration we experienced from Aratellus both onshore and offshore throughout the project. The machine performed impressively, delivering increasingly good results as the Aratellus team sought to constantly optimise its performance. We are delighted to have worked with them on the project”.

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