The FFCPT - an innovative and cost-effective option for supplementary offshore windfarm reconnaissance data acquisition

This paper presents the Free Fall Cone Penetration Test (FFCPT) as an accomplished, proven and efficient methodology developed for maritime defense and marine geotechnical surveys. The FFCPT can be used to investigate a wide variety of seafloor sediment types and was designed to employ penetrometers of varying mass and size, to achieve penetration into the seafloor by 15 m or more. The FFCPT can be operated in stationary or moving vessel mode, with the latter method allowing the survey vessel to maintain a speed of up to 8 knots. Interpretation of FFCPT data requires careful analysis and correction, considering the high penetration rates involved. The FFCPT is an acceleration-based system, that is robust enough to survive impact on a hard seafloor. Whilst the FFCPT will not replace existing cone penetration test (CPT) methods, it can yield reliable supplementary data to increase the efficiency and coverage of reconnaissance offshore site investigations, provided appropriate analysis methodology is followed. The FFCPT can be used to generate rapid initial datasets for comparison to more conventional and accurate methods, such as the static cone penetration test.