Stereo Particle Image Velocimetry (PIV) is an advanced measuring technique for obtaining 3D velocity information in a plane. PIV can be used to investigate the spatial structure of a flow by efficiently measuring in multiple planes. It is an important tool for the experimental validation of CFD calculations and for obtaining flow field information. This information can then be used for appendage or propeller design for instance. This technique is based on the measurement of the displacement Dx of particles in a target plane between two successive light pulses with a time delay.