Taiwan offshore wind boom

The decison comes on the back of a series of successful cable trenching and Seabed levelling campaigns in the country with further contracts in the pipeline.

Rotech successfully completed its latest major scope of work in the country in June 2022 having been contracted by a leading international marine infrastructure player to assist with de-burial and cable trenching operations on a key offshore windfarm.

Challenging project

Rotech mobilised its TRS1LD jet trencher into water 30-55m deep to carry out de-burial of wet stored export cable sections, export cable remedial burial works, inter-array cable remedial burial works and inter-array cable backfill works.

With outriggers and clump weights set up forward and aft of the trenching tool and connected with running lines to control orientation, the TRS1LD remained suspended above the seabed cable to complete all trenching operations.

The vessel’s DP positioning system was used to move the trenching tool along the cable routes with USBL transponders fitted to the tool providing accurate data on the location of the tool at all times.

Trench depth was monitored real time using a tool-mounted sonar imager with the client carrying out their own survey to confirm that the completed trenching ops met the required specifications.

“This was a technically challenging scope for a valued client and we were delighted to deliver it on schedule and on budget,” said Stephen Cochrane, subsea director of subsea, Rotech. 

“To avoid possible free span, the de-burial and remedial trenching were completed using minimal power. To establish the appropriate power level our crew completed trials on 10m sections at various levels (between 30-80%) and at various standoff distances from the cable/seabed (1.3m standoff from cable and 2-4m offset).”

“Once the trials had been completed we were able to complete the actual trenching scope with the optimal settings to achieve the client’s desired trench specification so there were no ensuing issues with the schedule.”

Having completed numerous OWF cable trenching and IRM scopes in Taiwan in recent years – including vital scopes at the state-owned windfarm offshore Taipei, Rotech has two scopes for a global fixed OWF infrastructure leader ongoing in the country with more to come later in the year and into 2023.

In March 2022, the company deployed its TRS2 Sand wave levelling system, RSBG boulder grab tool and TRS1LD shallow water jet trencher at the Changfang and Xidao Wind Farm to conduct a significant sandwave clearance, debris de-burial and boulder removal scopes which is still currently ongoing.

In July, Rotech subsequently mobilised a further TRS2 to the region execute a sandwave clearance campaign at the Yunlin OWF, work which is again, ongoing.