Quote:
A precursor to the effect under study was witnessed in 18th Century British canals as a wave which would continue along the canal for miles after a barge stopped. This "standing wave" exhibits the properties of water exploited to localize a submarine some depth below the surface.
That was not a standing wave but a soliton wave and that does not happen on open sea. That wave appeared because the waters were restricted. Normal ship wave systems diverge radialy and quicky reduce in height. If you want to detect that, the sub should not be submerged too much and the sea water should be clear. Here's a pic
Solitons also travel ahead of the ship (normal ship waves never) and can fully reflect on e.g., a dam wall and return to sender. The solitons occur when a ship enters a sudden narrowing. Reflected solitons exiting the channel can partially reflect back at the widening point.
Even wiki has something to say, although it says solitons are non-linear, which is not true for water solitons (That is, direct analytical equations predicting them are not linear, numerical simulations using linear theory can predict them). The wiki content seems to be written by a mathematician, hence it is non-understandable and useless if you're not a mathematician.
Note that the waves coming from the ship aren't standing waves either, they travel but with the same speed as the ship. From the ship's point of view, that does seem like a standing wave, but not from the point of view of a fluid particle.