Advanced hydrophone lessons - calculating speed?

[Paul Riley]

I would like to begin a thread on advanced Hydrophone lessons ( not sure if they have been done before ) as I want to start getting used to gathering ship data without ever having to raise the scopes,ideally for late war scenarios or against warships.Initially I am wondering how to get quite reliable results on speed.I understand the theory in counting revolutions to get speed but don't know how to do it correctly,or even how to translate this data into speed results.
If there is a link to this info you could direct me to that,or just teach me from scratch,your choice
I can say once I am close to mastering advanced hydrophone use to gather data I can start to enjoy the finer points of commanding a UBoat.
Maybe the next lesson could be 'determining ship course when submerged' ?

[Didd]

There was an excellent thread on this a short while ago, outlining a technique whereby you could determine course, speed and range (without counting rpms) and even shoot blind (target id may be an issue though).

There was a video if I remember rightly. I've got a pdf of the technique if you are interested.

Here's the link to the thread:
http://www.subsim.com/radioroom/show...ght=hydrophone

[Paul Riley]

Thanks for that Didd
And yes,the pdf could be useful,thanks again.

[Didd]

Try this:
http://www.subsim.com/radioroom/showthread.php?t=160817

[Paul Riley]

I checked the first video,and it started well but quickly got VERY complex with lines and marks all over the place,a bit TOO complex for my taste.I am going to see if there is any official material on the web regarding how real UBoat captains plotted courses and gathered speeds while submerged,i'm not even certain if they did,I imagine submerged data gathering to have evolved and been more important as detection technology increased,leading to the birth of the nuclear submarine,which has the equipment to build an accurate picture of whats happening above totally submerged for months at a time.
Still,I wouldnt mind understanding how it can be done.
The pdf file may be a better option.

Thanks very much for your links by the way

[BillCar]

The video posted is the correct way to do it if it is going to be done (there's not really another way if you want speed, heading and exact range to target). This method was not commonly employed by U-boat commanders at all, but it does work. I don't tend to use it, simply because it does defy realism a bit, but on those rare occasions when I do, I find that it works quite well.