Bathymetry study for the route of a dynamic cable to connect the harhlab laboraty at bimep test site

Abstract

Dynamic power cables are used to connect offshore renewable systems to electric grid. These cables are a critical component, especially in floating offshore renewable systems, which are exposed to cyclic loads resulting from the floating structure movements. These loads are transmitted along the cable, leading to motions over the seabed. Accounting for soil characteristics and seabed bathymetry results critical in order to minimize friction damage. In the same way, the touchdown point of the cable is often a constraining section when assessing cable life. This point is subject to frequent impacts and it needs to be well determined. Additionally, the seabed in that area must be characterized in order to protect the cable properly or even change the cable route or move the touchdown point by redesigning the configuration of each component. Thus, the accuracy in the installation of a dynamic cable can avoid future problems. This paper addresses a bathymetry study done for route of a dynamic power cable deployed to connect a floating testing platform, HarshLab, at BIMEP test site. The installation of the power cable is planned to be done with a DPI vessel. The dynamic cable will be mounted in the vessel in a reel with both ends with electrical submarine connectors installed. Therefore, the route of the dynamic power cable cannot be modified during installation. The surveys have been carried out with full coverage, using a Norbit–iWBMSc (Compact) multibeam echo sounder, installed on board the AZTIMAR BAT vessel, with a resulted net of 25cm. of resolution. The multi-beam bathymetry has addressed the more suitable route for the cable. Submarine inspections performed with a ROV has been used to confirm visually the identified objects to be avoided in the cable route. As result of this study, it has been selected a route with minimum risk for cable damages.