[Staple_Diet]

In comparison to conventional nuclear sub this method would be much quieter. But also much faster over long distances. You have two issues with subs, stealth and positioning. If you know, or have high confidence, that a combatant sub force is in X pos, and have Intel on its AVG speed then you can plan accordingly. Tech like that described above means a sub force can be more quickly repositioned, or deployed. You have Intel that X vessel was docked two days ago? Well it could be in the south pacific today.

One thing to keep in mind, there is a reason this is published publically. PLA want this out there for a reason, either to sow worry and concern or to mislead.

[JumpCrisscross]

> this method would be much quieter

Source? Cavitation on propellers is a major source of uncloaking. This sub sounds fast but traceable—perhaps more ideal for a weapon than a vehicle.

[Staple_Diet]

The method described in the present article doesn't rely on rotating propellers that produce vibrations, thereby reducing one of the major sources of noise.

[JumpCrisscross]

> method described in the present article doesn't rely on rotating propellers that produce vibrations, thereby reducing one of the major sources of noise

The main source of “hull vibration and noise” from propellers is cavitation [1]. Laser propulsion directly cavitates.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4549849/

[Turing_Machine]

It sounds like it's basically a gigantic cavitation noise generator, so yeah, I'm not imagining that it could possibly be quieter.

Today's submarines go to great lengths to avoid cavitation for just that reason.

Typically there's a velocity beyond which the vessel does not go if it wants to remain stealthy, as going faster than that drastically increases the cavitation noise.