Fluid dynamicists do it with models

Found via the Physics arXiv blog: Dead Waters: Large Amplitude Interfacial Waves Generated by a Boat in a Stratified Fluid.

It’s a pretty dry paper, but explains an interesting phenomenon - when a layer of fresh water flows over a layer of salt water (say, in the runoff from a glacier or ice floe), turbulence between the two layers can cause a boat to slow or even stop dead, even in completely calm waters.

They even have a video demonstrating the effect - with a little toy boat in a tank of coloured water. Like so.