The aerodynamic interaction of finite wings flying in very close proximity is investigated experimentally. Docked wings are also examined. Tests were carried out in a water tunnel and Particle Image Velocimetry (PIV) was employed to generate velocity data along Trefftz planes. The results indicate that vortex lines “jump”, or reconnect from one wing tip to the next, even in cases of some physical separation. These data can be used to calculate lift and drag and our calculations indicate significant reductions in drag.