Not just rumor
http://ieeexplore.ieee.org/document/7729229/?denied
Abstract:
Submarine detection plays an important role in modern wars. As a potential technique, synthetic aperture radar (SAR) is used to detect submarines through detecting their wakes on the sea surface. This requires the images of submarine wakes under all kinds of conditions. However, it is difficult to acquire these images by field experiment. In this paper, we propose a method to simulate SAR images of submarine wakes. First, the sea-surface shape with submarine wakes is acquired via hydrodynamics approaches. Then, the scattering coefficient of each patch on the sea surface is calculated based on a scattering model. Finally, the image is generated using the SAR imaging model.
http://www.london-research-and-development.com/Ship-Wake.html
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=0ahUKEwj8zOiF3O_TAhWGYyYKHS75D18QFghBMAU&url=http%3A%2F%2Fwww.sarusersmanual.com%2FManualPDF%2FNOAASARManual_CH12_pg277-304.pdf&usg=AFQjCNHGgj_oMe12YfmXL7zySIf6NB-P6g