Field observations and analytical modelling of drag-embedded anchor installation and post-installation performance

Drag-embedded anchors (DEAs) are widely used for offshore floating facilities due to high-capacity efficiency and cost-effective installation. However, the installation of modern floating energy systems is constrained by design line tensions that often exceed 1000 t per line, while most anchor-handling vessels are limited to about 500 t. These limitations, combined with uncertainties in embedment behaviour and capacity mobilisation, have led to overly conservative design practices. This study provides prototype-scale field evidence on DEA installation performance in sandy and clayey seabeds, addressing the scarcity of full-scale data. The observations show that anchor embedment stabilises within the first few minutes, indicating that the conventional 15–30 min hold period is unnecessarily conservative. Shorter, performance-based criteria could therefore reduce vessel time, costs and operational risk. Furthermore, modelling with a coupled mooring line–anchor framework, validated against field observations, demonstrates that anchors installed at reduced initial tension can mobilise additional capacity through post-installation drag, reducing installation demands and risks. Parametric studies further reveal how soil layering, mooring configuration and installation tension influence post-installation embedment and resistance. The combined insights inform more cost-effective and operationally efficient anchoring system installations, supporting improvements to offshore anchoring guidelines and design practices.