Advanced hydrophone techniques.

[greyrider]

i just want to add to this post guys to let you know that if your using the bearing speed charts and the rpm charts to attack ships, that there are a couple of other attributes to those charts that you should know, and i will list them below.

1. the bearing speed charts are visual, meaning you can use the periscope to shoot also.

situation: you see a t-3 closing, and your in a good 90 decree to his course, from the rpm charts his turn count is 34 rpm, the t-3 is traveling at 11 knots.

now the bearing speed chart states that a ship traveling at 11 knots across the bow, using the bow torpedoes to engage it the firing bearing will be either 14 decrees or 346, depending on which way he is closing on you.

lets say the t-3 is closing from the starboard side, that means the firing bearing will be 14 decrees. preset the periscope to 14 decrees, watch the ship travel to the firing bearing of 14 decrees and when his funnel is at bearing 14, fire!

the only time i use the hydrophone now to fire is if i cant see the ship. if i can see the ship i use the periscope with the rpm charts and the speed bearing charts.


2. you can use the bearing speed charts and rpm charts on the move, meaning you dont have to be stationary to fire, you can close on the target. this is about as close to a fire and forget as i can get.

3. once you know what the target and its speed is, you can manually input the bearings and speed from the charts into the tdc and fire like that.

4 the bearing speed charts are also radar bearings to fire at to.


so the bearing speed charts can be used:

visually in the periscope,
by sound in the hydrophones,
using radar to engage the target,
manual tdc input.

i have developed a sonar overlay mod that i would like to see up to the community, i cant mod it, i dont know how to do that, but i can build one on the map if theres an interest ill post pictures and then if it can be modded then any modder is welcome to mod it.

[Trav_R]

I know what you're saying, but the whole idea of firing just using the hydrophone has sort of a paradox. The big benefit of using the hydrophone to manually fire is that you can use it without seeing the target. The problem with this is you don't know the target's speed unless you've actually seen the target to ID it. So, if you've seen the target and were in a position to strike, why bother with the hydrophone? It's biggest benefit is almost perfectly cancelled by its weakness. If you have enough information about the target to get on a perpendicular course with it and close to its path, then you have enough information to manually set up the TDC and fire visually. Even if it's heavy fog, you can still see up to about 400m and with careful hydrophone work you can work yourself into that position without too much difficulty.

Although it may be slightly easier to just point your optics at the correct bearing and fire when the target reaches it (assuming you know his speed accurately), you're taking a chance on hitting the target in one of its strong areas and not doing much damage to it. Even in heavy fog, I'd rather just wait till I can see him and them aim for his fuel bunker/engine room. I'd like to use this hydrophone method but the whole idea of having to see the target first kind of makes it pointless as far as I can tell.

[joea]

Well didn't the USN try before the war to use the hydrophone only for submerged torpedo attacks? It didn't work out apparently...(neither did their torps for the first part of the war).

[JohnnyPotPie]

BRAVO SIR BRAVO!!!

[Canovaro]

Thank you for pointing out how to figure out the target's course!
I'm sure I will you this a lot!



Anyway about ID'ing the target to figure out speed as discussed above, You don't have to do this in a reported convoy, because the speed is given in the report. In any other case, you're right, except when you use Greyrider's method, which is of course a bit unrealistic.

You can also guess what it is by the sound type and frequency

Sorry for bringing up an old thread, but it's a good one isn't it?

[Canovaro]

I did some testing while on patrol.
East coast of England, I heard a warship, my hydro man said it was moving "schnell".
I figured that would be something between 20 and 30 kts, so I tryed the stuff of the_rydster, at the top of this thread.

I let the sonar man report the target bearing, noted my own bearing, and turned on the timer.
After 3 minutes and 15 seconds I let the sonar men report again and noted my own bearing.
After another 3 minutes and 15 seconds I let the sonar men report again noted my own bearing.

I figured out the absolute target bearing by doing "relative target bearing" + "own bearing" for all three observations.

Now I had three bearings:
A: 28+134=162
B: 35+134=169
C: 46+134=180

Below you see the corresponding lines I made.
I also made a circle with a span of 2 km to each side.
I moved the circle over the three line untill I had a straight line through the point where the circle cut line A and C, and where the center of the circle was in the middle.
I made a new line through these three points.
Then I made another circle of 3 km to each side and did the same thing.

If my guess about the speed being between 20 kts and 30 kts was right , the ship's track should be between line D and E.

(the speed turned out te be 27 kts in a radio message that came in later)
Anyway I never had the need to go after it since 27 kts was way to fast.

[Canovaro]

Wait a minute, that ain't right.

I draw 2km and 3km circles. For a 20-30 kts speed that shoud have been 20 and 30 km.
If that warship was sailing between 2 and 3 kts, the drawing should have been right.

Bernaaard! :rotfl:

[TteFAboB]

It's possible to fire indeed with no data other than the hydrophone, especially if you get a nomograph or make one yourself, but I can't score consistently on the small merchants. I stopped firing at the smaller merchants to avoid wasting fishes and also because I'm tired of lying to my crew: "No good men, that one was another dud..."

I've managed to score hits on the large vessels though. The tough part is judging speed because the damn ruler has that 50m margin of error and also setting a precise 90 degree heading.

[Mittelwaechter]

Hitting targets >>without<< visual data?

http://www.subsim.com/radioroom/show...mittelwaechter

There's a tutorial-clip available - scroll down.