Current advancements in foundation design methodologies have given a new focus on acquiring in situ G0 data to compliment current laboratory testing methods and to provide G0 profiles for design in a parameter bound framework. Seismic CPTU (SCPTU) data was acquired from sites within the North Sea both in drilling and non-drilling mode. An assessment of the data showed significant scatter in the interpreted results. Current standards provide little guidance on what is ‘accurate and reliable’ data, hence an assessment was initiated to better understand the reasons for the scatter observed and what is to be considered reliable data. This paper discusses the assessments that have been undertaken and covers: the seismic testing set-ups, how the data was acquired; how the data was interpreted; offers suggestions on what can be causing the scatter; and provides commentary on how to gain confidence in the data acquired. This study highlights the need for greater understanding of SCPTU data and closer client-contractor collaboration. It is recommended that project specifications clearly define SCPTU reporting beyond the standard requirements, where comprehensive information of the seismic data acquired and the methods used to derive the vs is needed to improve confidence on data evaluation and interpretation for the design purpose.