Thinking About Evading Searchers

[Kapitan]

I would hit 35 knots in viper if i was being chased by the FFG other than that like heck will i pass 15 knots unless evading a torp

[DS]

Searching for a submarine is like searching for a needle in a haystack. The faster the sub moves, the larger her noise signature, and therefore the larger a needle she is, making her that much easier to find. If we assume that a submarine stopped dead in the water has to be passed right over head to be heard (Needle), in a 100 square kilometers of ocean (haystack), it will take either a lot of time, or a lot of assets, before statisticaly you pass over the sub. If she is moving and creating a 2 square kilometer sound signature around her, she is statistically now much easier to find (much larger needle).

But then, I'm only a cyber-skipper. Maybe the BTDTs know somethign I don't.

[SeaQueen]

Now you're starting to think like I do. The thing is, she might be a larger needle to find, but she's also a moving needle which would be harder to find. One would expect that do one's best, there'd be a best compromise between being a moving needle and being slightly larger needle. I wonder where that compromise lies.

Originally Posted by DS

Searching for a submarine is like searching for a needle in a haystack. The faster the sub moves, the larger her noise signature, and therefore the larger a needle she is, making her that much easier to find. If we assume that a submarine stopped dead in the water has to be passed right over head to be heard (Needle), in a 100 square kilometers of ocean (haystack), it will take either a lot of time, or a lot of assets, before statisticaly you pass over the sub. If she is moving and creating a 2 square kilometer sound signature around her, she is statistically now much easier to find (much larger needle).

But then, I'm only a cyber-skipper. Maybe the BTDTs know somethign I don't.

[DS]

In thinking more about this, it might be more of an issue of moving into an area already searched rather than moving at a given speed. If you knew what areas had been searchd, and where the searchers were now, you could conceivably move into a pre-searcehd area and be safe for a while.

More realistically though, if you had no way of knowing what areas had already been searched, or what the size of the search area was to begin with, you are still faced with the same problem.

Still, there might be some mathematical probability formula that could be invoked to give one the best odds, but I have no idea how one would calculate that.

Cheers.

[SeaQueen]

Originally Posted by DS

More realistically though, if you had no way of knowing what areas had already been searched, or what the size of the search area was to begin with, you are still faced with the same problem.

Still, there might be some mathematical probability formula that could be invoked to give one the best odds, but I have no idea how one would calculate that.

I know what the probability of detection is as a function of time for a searcher moving randomly against a stationary target. In general, the effect of a target moving randomly is to take a searcher who has some kind of more organized search and turn it into a random search. It's easy to see that if you consider what the searcher's motion looks like in the reference frame of the target.

Huuum... I think I have something fun to play with at work today. :-)

[LoBlo]

Thing is that what if your searcher is faster than you are like helos and use active sonar.

Then the needle just got bigger and the hackstack smaller.

[DS]

Let's look at it in this (admittedly simplistic) example.

Let us assume you have a 100 sq km search area, with one search asset that can scan a 1 sq km region at a time. I takes 5 minutes to complete the scan of 1sq km.

Let us also assume that when you are stationary, your noise signature gives a searcher a 50% chance of detecting you in the space of that 5 minutes before the searcher moves on. If you are moving, and thereby making more noise, the searcher has a 66% chance of detecting you.

With those constants, let's run the calcs:

If you stay still, you have a 0.5% chance of being detected on the 1st search grid. If you move from one grid to another, you have a 1.2% chance of being caught (66%/100 grid squares x 2 grid squares occupied during search phase 1).

If we assume this calc runs 100 times for the 100 squares searched one at a time, you have a 50% chance of being detected if you stay still, vs, a 120% (apparently statistically certain detection) chance of being detected if you kept moving.

Know, I am NOT a statistician, nor am I a real word tactician. Still, if you acknowledge your chances of detection are smaller the quieter you are, and you have no way of knowing if you are actually moving TOWARDS a searcher instead of away from one, it seems to me you are better off staying still. That said, in the real world, you almost always have some information, but never all information, so if I hear active sonar ranging to the south, I may choose to move away, even though I may be unwittingly moving towards a silent enemy in wait to the north.