Naval architects and propeller designers always knew the importance of propeller inflow measurements at the ship scale. The initial motivation was to compare the measured wake with model tests and derive recommendations for wake scaling procedures. Nowadays, the main intention is to validate ship scale CFD and better understand and utilise the energy efficiency potential of vessel propulsion. Developing measurement technologies enabled the design and realisation of a new and robust flow measurement tool which is not dependent on vessel geometry and porthole locations. The successful PIV measurements performed on the tanker within the JoRes project showed that this technology works and can be used on other vessels. The installation, performance and removal activities may be aligned with normal vessel operations (dry-docking, post-docking trials) and do not require significant off-hire time which makes it attractive for further comprehensive investigations on other vessels.