In preparation of the JoRes project, MARIN recently concluded PIV tests with seawater in a basin. The aim was to test the functionality of the system in seawater with naturally present particles for seeding. The setup was sized to represent geometry and working distances as would be applied on the MV Regal within the JoRes project. Results were very encouraging: the naturally present particles deliver good quality seeding and the needed full-scale working distances are achieved. This is an important step towards the project’s ground-breaking full-scale wake field measurements.