Is it possible in SH4 1.5

[CaptainD]

Hi everyones!

In many movies and books, novels or diaries, it is said that a sub can estimate the speed of a potential target by hearing the target's screw speed.
Is it true and if yes is it possible to do that in SH4 1.5?
If possible it could be another mean of getting a target's speed!

[doulos05]

The short answer is 'no'.

The long answer is "No, because Ubisoft used a very limited number of sound samples so you can't differentiate between 'slow', 'medium', and 'fast'." But that's ok because the really long answer is

"No, Ubisoft used a limited number of sound samples, but that's ok because Fleet boats lacked the intel necessarily to accurately use beat count to assess speed and so they likely did not use that as any more than broad estimations (like, 'slow', 'medium', and 'fast'.) That method of speed assessment didn't come into it's own until computers and the worldwide sonar net (whose name I'm blanking on right now) gave US subs access to a database with beat counts and sonar profiles for pretty much everything in the ocean."

[CaptainD]

Thanks for the answer!
I think that this urban legend comes from movies when you can see the sonar man giving a speed in knots abouts targets or DD.
I am talking about WWII movies of course and about the sonar/computer system I remember having seen something about a system like that in the movie "The Hunt for Red October".
For the same use in WWII, may be it was possible if the target has been precisely identified.
In that case, knowing the performances of the target, the screw speed could be interpreted to give a target speed... or not.
It also depend on the ability and skills of the sonar man.
I remember having read that a sonar man of the HMS Unbroken, Lieutnant Command A. Mars, had spécial capacities.
One times, jailed in the bow torpedoe room for some blunder, he eared foe DD asdic without any equipment.
Of cours, nobody aboard the sub believed him.
As the man continued to talk about the pings he eared, L. C. Mars ordered the sub some feets up and then the sonar man on duty eared in his headphones the pings coming from an Italian or German DD somewhere over the sub.
The man was immediately extract from is cell and thrown at his duty place.
A friend who had been on duty on french submarine told me that people on charge of sonar service were able to ear "The grass growing".
I think that L.C. Mars sonar man was close to that.

[twm47099]

Originally Posted by CaptainD

Thanks for the answer!
I think that this urban legend comes from movies when you can see the sonar man giving a speed in knots abouts targets or DD.
I am talking about WWII movies of course and about the sonar/computer system I remember having seen something about a system like that in the movie "The Hunt for Red October".
For the same use in WWII, may be it was possible if the target has been precisely identified.
In that case, knowing the performances of the target, the screw speed could be interpreted to give a target speed... or not.
It also depend on the ability and skills of the sonar man.
I remember having read that a sonar man of the HMS Unbroken, Lieutnant Command A. Mars, had spécial capacities.
One times, jailed in the bow torpedoe room for some blunder, he eared foe DD asdic without any equipment.
Of cours, nobody aboard the sub believed him.
As the man continued to talk about the pings he eared, L. C. Mars ordered the sub some feets up and then the sonar man on duty eared in his headphones the pings coming from an Italian or German DD somewhere over the sub.
The man was immediately extract from is cell and thrown at his duty place.
A friend who had been on duty on french submarine told me that people on charge of sonar service were able to ear "The grass growing".
I think that L.C. Mars sonar man was close to that.

According to the Fleet Submarine Sonar Operator's Manual:

"4. Target's speed is estimated principally from the turn count obtained by the SONAR operator, or from the periscope identification of the target. This information also is approximate. Therefore, it too is corrected as the problem demands. "

http://www.maritime.org/fleetsub/sonar/chap10.htm

In that manual, the method for determining and reporting the prop count is taught. Elsewhere, in one of the other manuals, the method for estimating target speed from prop count is given.

Of course without knowing the particulars of the target, it is an estimate, and would be improved on by using other methods, which are also estimates.

Tom

[CaptainD]

Thanks for the data!
One estimate + another estimates = sum of error margin which may be not little.
After reading theses manuals we see that knowledge of the target and good estimates of the target speed are mandatory and I understand why Ubisoft had not implemented theses function in the game.

[Ruff EL]

I believe the worldwide sonar net is called SOSUS....not sure what that stands for or if im right, but ive read about that a few times as a sonar net across the globe

[doulos05]

Well, I guess I stand corrected. But it takes intel to translate turn counts into knots. Intel which, I was given to understand, was unavailable to fleet boats for most of the war.

[Hitman]

Turn count gave in real life an aproximate figure, based on many different factors. That included the type of ship, number of screws, etc, which a sonarman with a fine sense could differentiate. I would be surprised if the error margin was less than +/- 2 knots.

And, as far as SH3/4 goes, yes it works because the game engine changes pitch and speed of the sound. In fact some time ago there was for SH3 a chart for all ships including some addon ones, and even a utility that you could use to "train" and get better at estimating. Only problem is that it was deadly accurate and with the limited number of ships in the game, it worked always too well and spoiled the fun.

[sharkbit]

I read in O'Kane's "Clear the Bridge"(It might have been "Wahoo", can't remember which one for sure ) that they used the method of counting screw revolutions to double check their target's speed. In fact, O'Kane bought a piano metronome on leave for use on the sub to aid his soundman in timing the count.

[CaptainD]

Thanks everybody!
Target speed data is mandatory for a shoot solution so having two means for getting it is the best but as it was not implemented in SH4 I think we have to forget it.