Mitigates the risk of undermining sea bed movements on infrastructure installed below or on top of the sea bed, including at anchors and around the jacket foundation of the substation.

Who supplies them

Coda, Octopus, DHI, HR Wallingford, Norfolk Marine and Subsea Protection Systems.

Key facts

The presence of scour (erosion of the sea bed surface) around marine structures is common. Large diameter structures, like fixed monopile offshore wind turbine foundations, are particularly prone to scour because of the deflection of water movement around the structure.

Drag embedment anchors are buried under the sea bed (see B.3.1 for further information). They require monitoring to ensure they remain buried at sufficient depth. Suction and pile driven anchors protrude from the sea bed but are typically small diameter structures meaning that scour is unlikely to develop as quickly. The shallow embedded depths of drag embedment anchors means that any scour that does occur presents a bigger risk to the anchor’s performance.

Scour is generally managed through rock (or grout, sand, or gravel) dumping. Mats are generally placed on top and these stabilise the infill material and prevent secondary scour. Frond mats, tyre-filled sacks and tyre-based mats have also been used.

Concrete mattresses may also be used, potentially with protective mats, where cables have become exposed.

What’s in it

Guide to a Floating Offshore Wind Farm