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View Full Version : Screw Revolutions to Determine Ship's Speed.


Patchman123
01-07-11, 04:15 PM
Screw Revolutions to Determine Ship's Speed. I heard about SONAR in World War II that tracks the speed of a ship by counting the number of screw revolutions on a ship by simply listening to them by sonar. On SONAR, the sonar operator uses it to judge the speed of the ship that he is target.

Now,
I'm wondering if we could simply have a way for the sonar operator to send the speed to the TDC as well as the Range and Bearing. It would be so cool to have a send speed to the TDC icon for Silent Hunter IV so that players don't have to guess what the speed of an enemy ship is. Are there other ways to measure speed, other than by visual observation? Visual observation seems to take a long time in combat, especially when they're shooting at you.

Why can't there be a sonar that gives you the speed of an enemy ship to save time? :rock:
:up:
It would save time. Shouldn't there be a sonar speed that gives the speed of a target? It saves me a lot of time tracking a ship. Can it be done in Silent Hunter IV?


http://www.maritime.org/fleetsub/sonar/chap4.htm

There is a prop count detector for the sonar unit. As you can see. This would be cool to have in SIlent Hunter IV, I think because I get the speed of a ship in less time that the current
game allows.


History

All nautical instruments designed to measure the speed of a ship through water are known as logs. [1] (http://en.wikipedia.org/wiki/Pitometer_log#cite_note-logs-0) This nomenclature dates back to days of sail when sailors tossed a log attached to rope knotted at regular intervals off the stern of a ship. The sailors would count the number of knots that passed through their hands in a given period of time. Today sailors still use the unit of knots (http://en.wikipedia.org/wiki/Knot_%28speed%29) to express a ship's speed. The speed of the ship was needed to navigate the ship using dead reckoning (http://en.wikipedia.org/wiki/Dead_reckoning), which was standard practice in the days before modern navigation (http://en.wikipedia.org/wiki/Navigation) instruments like GPS (http://en.wikipedia.org/wiki/GPS).
During World War II, pitometer logs were often interfaced directly into warship fire control (http://en.wikipedia.org/wiki/Fire-control_system) systems. This interface was necessary to allow gunnery and torpedo fire control systems (http://en.wikipedia.org/wiki/Torpedo_Data_Computer) to automatically track targets.
While the pitometer log is very commonly used today, there are a number of other logs that are also in use. These logs include:

Ships had a pitometer log to determine ship's speed that was integrated with the TDC. Why isn't this in Silent Hunter IV? Why isn't the sonar at its full complexity? Sonar in the game should be more advanced than presented in the game because it would be nice to be able to detect mines, marine mammals, etc. I just want a better way to calculate a ship's speed. I mean Nisgeis TDC has the ability to determine a ship's course, but not its speed.

Nisgeis
01-07-11, 05:54 PM
As far as I recall, all efforts to provide useful information from the sound you hear have failed. The problem is that the sound effect doesn't correspond directly to the actual RPM of the ship screws above and below a certain narrow range.

The sonar is a very simple approximation, which is why there are no frequency filters to cut through wave noise nor a beat counter - as those things aren't modelled.

As for the pit log being fed into the TDC, it is. It's fed into the PK part of the TDC. Of course it's Own Speed and not Target Speed, but that's fair enough really.

Webster
01-07-11, 06:12 PM
just going by memmory here but i think its just a basic sound snippet they use at different volumes so the actual revolution pulses you here are constant and thereby useless for determining speeds. plus i think they have just a few sounds shared and used for all the ships grouped by class or types.

the best you can do is pinpoint the bearing and after a few readings calculate the speed by the distance it traveled.

ETR3(SS)
01-08-11, 01:08 AM
So what was wrong with the first thread you posted about this, 30mins before this one? http://www.subsim.com/radioroom/showthread.php?t=178853