I suppose she it would have some kind of magic cloak of invisibility.

Wouldn't work, they can still track it using tsunami warning buoys.

Going dark by minimising emissions is quite effective I believe. The effort expended trying to find ships that want to be found suggests knowing the precise whereabouts of a vessel at all times is not as easy as post #12 implied.

Now THAT'S what I call a wake!

Seems possible that the Doppler could be processed along with a bearing from a passive sonar array to give a track perhaps? I don't know enough about sonar but remember seeing waterfall displays showing the frequency shift as a target moved relative to the sensors. No idea how this can be processed though.

I think this discussion needs a smattering of fog of war and reality to enter the mix.
Technical discussions on paper soon enter the waste basket in war. We lost enough high tech naval assets to relatively low tech delivered munitions in the Falklands to remind us of that.
An interesting comment was that "If we had taken our stored WW2 Barrage Balloons with us we may not have lost so many ships" is interesting.

Rules of war.
The enemy will do something you have not anticipated.
Plans vary rarely go to plan.
If the enemy can get through (our defences) it will get through.
Most importantly, never underestimate the enemy.

If it was that good, submarines would not need attack periscopes :8

What's the visible horizon from a periscope, though? Can't be far, can it? Knowing where a ship like this was to within a dozen miles is more than good enough if you're not interested in sinking it, just keeping a tail on it's whereabouts.


Edited:

Just had a poke around on the web. No idea how far out of the water a periscope pokes, but if it was 10ft then the horizon limit is about 4 miles. If it's 20ft the horizon limit is about 6 miles. If it was 30ft the horizon limit is just over 7 miles. Less than I thought. May be periscopes poke a lot higher out of the water though. A 50ft high one could see out to a bit over 9 miles. 50ft seems high to me, could well be wrong though.

Monitoring a vessel can be done at a distance using passive sonar and a series of manoeuvres to get a range and bearing. The sonogram will give more information about the vessel.. The attack periscope (is/was) is used to get a firing solution by acquiring more precise data on the target's course, speed and range, including confirming the identity of the target. It is much smaller than the conventional periscope which has a larger radar cross section but is used at longer distances or where there is no threat. But either way. a trailing submarine is a boat in trail and is outside the scope of my question.

Those figures are for waterline visibility. If you add in the height of the ship, then they look more realistic (e.g. a periscope at a height of 20ft can see a 70ft warship out to 13Nm.

On the wider point, target-motion analysis as a method for estimating range from passive sensors has been around in crude form since before the 2nd world war. On modern submarine with automated analysis it is much more sophisticated.

According to the wisdom imparted to me by the Internet, apples-to-apples (say, same launch weight?), the warhead ought to be actually smaller.
The reasoning:
(1) All that speed (and attendant friction) doesn't come from nothing - need to carry more fuel.
(2) Hypersonic means surrounded by plasma, so no guidance corrections until it slows down near target. At which point it can be engaged just like any supersonic missile at close-in range.

If the design chooses not to slow down, then:
(1) The warhead must give up some of its HE weight to a heat shield, and
(2) It will not be GPS accurate. So ironically, it could really use a bigger warhead.
Perhaps this last point can be solved with some clever optical terminal guidance, but it certainly won't be easy to do, with the nose cone busy trying not to melt.

Thanks. Makes sense. I had a feeling there were ways to get range as well as bearing from passive sonar, just didn't know how it was done. Presumably modern signal processing makes that easier and more accurate.

There are quite a few USN P8 maritime patrol aircraft based at NAS Jacksonville so I would imagine they would be tasked ?

In crude terms, you put a zig zag in your course to form a baseline from which to triangulate the bearing. Do it a few times and you have a last known course and speed - which is why skimmers zigzag in the face of an SM threat.

I think that if you have the required clearance and a “need to know” you could get a full briefing as to what the crew had for breakfast.

I'm guessing that the US have SAR equipped satellites that could pinpoint it 24/7, all weather if required?

It wasn't good.

Kasha.

If she suddenly sank in rough weather, that would not look very good.

There is that much orbital coverage to provide 24/7?