No you'd expect any submarine contact to take place at very low speed. The main source of noise from submarine are either from mechanical equipment inside the submarine, pumps, engines etc or from an effect called cavitation. This mainly occurs from the tips and forward edges of the propeller where small bubbles are created on flaws in its leading edge.  This can be minimised by reducing speed, so when attempting to run silently, submarines are generally limited to roughly 3 knots of speed or less, depending on surface design of propeller blades.

You'd only expect high speed submarine impacts from attack submariens, that use a technique that involves sprints then drifts to create an artificial baseline for triangulating acoustic targets while hunting other submarines.

Any idiot can face a crisis - it's day to day living that wears you out.

Another possibility is that they have detected each other, and both tried to simultaneously 'disappear' and find the other.

You mean like hide and go seek?

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