Plate anchors are widely understood to be the most efficient anchor in terms of material usage. Typically made of medium-strength steel, and deeply embedded below the seabed (where the soil strength is greatest), their holding capacity to weight ratio exceeds all other anchor types. Plate anchors typically require one-quarter to one-third the amount of material and labour as piles. This translates to huge cost savings when it comes to material, fabrication, and transportation. Additionally, plate anchors provide a significantly reduced carbon emission benefit in the form of less steelmaking and size/weight to transport.
Suction Embedded Plate Anchors (SEPLAs) were pioneered by InterMoor, a brand in Acteon’s Engineering, Moorings and Foundations division, in the 1990s and today are the only type of plate anchors used in the commercial industry. SEPLAs are loaded into the end of a suction follower (similar to a suction pile) which generates the differential pressure needed to drive the anchor into the seabed. The follower is then recovered, reloaded and re-used with another plate anchor.
SEPLA technology, like suction pile technology, is well suited to installation in soft clay conditions and deep water. However, many proposed FOWT developments are in shallow areas with sand or mixed soils. A new means for quickly installing plate anchors that do not exclusively use suction technology is needed.
Acteon is currently developing a Flexibly Embedded Plate Anchor (FEPLA) system to address this need. The system will consist of an updated SEPLA design for clays, and a new plate anchor configuration optimized for sands. These anchors will interface with a new multi-function follower capable of embedding anchors by suction, vibro-hammering, impact hammering and even jetting. The follower will be modular allowing for re-configuration to include any needed combination of embedment methods. For example: combining vibro-hammering with impact hammering in stiff mixed soil layer conditions.
Acteon is uniquely positioned to make FEPLA a reality. InterMoor is already the undisputed leader in plate anchors. Other Acteon brands including MENCK, with their range of subsea impact hammers and pile driving capabilities, and LDD with their subsea drills, have vast experience in developing subsea machinery. When realised, the FEPLA system will be the most efficient and fastest industrial anchoring system yet developed and the only system that checks all the boxes for an ideal FOWT anchor.
Tom Bauer, Principal Engineer, Floating Renewables Innovation, will present this new anchor concept at the Floating Wind Solutions conference in Houston on January 31st, 2023.
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Acteon’s solid domain knowledge in mooring design and offshore mooring operations spans the globe. We have installed some of the largest offshore assets in all water depths. We provide an integrated service covering the entire project lifecycle, from engineering, mooring design, procurement, and installation, through to maintenance and decommissioning.