Wave and tidal energy technologies are in there infancy in commercial deployment and operation. Although many devices exist in concept, only a small number have progressed to scale testing either in test tank or scaled sea conditions. With a number of devices existing at the concept stage and all seeking resources to progress prototype models, it is important to establish what current practices are adopted to appraise the performance of concept devices and the quality checks implemented to ensure a degree of accuracy is attained when undertaking this. In addition to the assessment processes undertaken, it is also important to understand how data produced from this early assessment is presented and used in order to establish appropriateness and fit for purpose. In order achieve this for both wave and tidal energy devices respectively they have been treated as two separate entities and as such this reports the current practices being adopted for wave and tidal devices and identifies the limitations inherent with current practices. The report is structured in a format which treats wave and tidal devices separately due to the different architecture associated with the devices and the physics of operation. Part A reports the limitations associated with current practices adopted in the early stage assessment of tidal devices, while Part B reports the limitations of current practices adopted for the early stage assessment of wave devices.