It's worth pointing out that this is authored by Stephen Chen who is a bit of a joke in defence news circles with a never ending supply of articles about how China has all these amazing weapons and technological advances that render the US helpless in comparison and there is one every few days or so.
https://www.scmp.com/author/stephen-chen
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.
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.
> 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.
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.
The very end of the article talks about "green shipping" but it seems like this propulsion method would produce crazy levels of heat. Wouldn't that have adverse impact?
Yeah, if I'm understanding what's going on here, it's going to be noisy as hell.
Cavitation noise isn't the only factor making a submarine detectable, but it's definitely high on the list. It's been used to detect submarines since WWII or thereabouts.
It says its using lasers to vaporize seawater all around the submarine which would create a submarine sized super cavity which would have very very low resistance. The problem is what happens when the bubbles collapse. That's what causes the cavitation noise, its when the bubbles collapse. They can do so with such force that they can pull metal out of nearby surfaces.
Yah. Meanwhile elsewhere people have torn apart the news. Seems that it is just a concept, no test in reality at all, not even parts of it in a lab. Maybe late april joke?