Yet another dumb question about manual targeting

[Platapus]

I was reading the SH3 wiki and came across some information that is either inaccurate or confusing. Since smart money will always back my being confused I wanted to ask the smart people here.

Reference: http://www.communitymanuals.com/shii...nual_Targeting

The TDC requires four pieces of information to calculate the correct gyro angle:

1. Angle on bow (AoB) - This is the direction of travel of the target relative to your u-boat's direction. See angle on bow for more information.
2. Bearing- This is the angle at which you observe the target.
3. Speed - This is the speed of the target. More precisely, it is the relative speed between you and the target.
4. Range - Although it does not effect the gyro angle as much as the three above, range DOES have an effect on the angle and thus checking the range prior to shooting is always a good idea.

Is that comment about the speed being the relative speed between the sub and the target and not just the absolute speed of the target correct?

The targeting instructions on the same wiki page do recommend that the sub be stopped when taking a speed calculation.

Is this right?

[P_Funk]

In general, the notepad device for determining target speed is only of limited use. It's worthwhile learning additional techniques such as the Three Minute Rule to accurately detect your target's speed.

I think you should take this bit right there as being most important. I don't think anyone uses that stopwatch thing for determining the speed of a target. Its buggy, inaccurate and altogether cheating when it comes to th challenge of manual TDC.

The TDC computes based on certain variables the solution. The relative speed between you and the target is nothing youneed to worry about. Just the target's speed needs to be imputed.

The three minute rule is the most reliable way I've found to do it. It also takes effort and practise so its worth it.

[Platapus]

[quote=P_Funk]

The three minute rule is the most reliable way I've found to do it. It also takes effort and practise so its worth it.

I agree I like the 3:15 technique. Not only is it accurate but it sure is immersive

[P_Funk]

Indeed. The feeling of starting the timer, monitoring it, gathering info, observing the target, marking everything down, then getting a positive solution... well its just everything that I love about SH3.

[Dantenoc]

You need to input the target's absolute speed into the targeting computer. The remark about the target's relative speed is meant to warn you that the defacto "notepad" method calculates relative speed instead.

This of course is because the method is based on trigonometry, taking into acount the target's AoB, range and baring change (as observed by the scope). All of these values will be negatively affected by your own ships movement, but baring change is especialy sensistive. For an extreme example, imagine yourself following a paralel course to the target, and traveling at the exact same speed... under this scenario, you will observe no bearing change whatsoever no matter how long a time you keep watching the target. The computer will think that the target is stationary when in "reality" It is moving just as fast as you are. See?

[GoldenRivet]

i determine speed by raising the scope, looking at the ship and marking its position on the map. then i will start the time and lower the scope to reduce the odds of detectiion. nearing 1 or 2 or 3 minutes later depending on the time i have i raise the scope again and plot the ships position on the map. use the ruler tool to measure the distance between the two points... then you can tell how fast the ship is going by how much distance is between the two points vs the time it took for him to cover the distance. this is the speed value i put in the TDC.

furthermore you can extend the ruler line out several miles ahead of the target ship - as long as the line passes through the two points you draw on the map you can get a really good idea of the path he is taking assuming he continues in a straight line for several miles.

finally i take a last minute range and AOB calculation, and put that into the TDC and fire.

as a rule of thumb i try to almost always be 90 degrees to the target's path and within 1200 meters of the target for accuracy.

if it is a convoy i will try to target a ship that is about 1200 meters away, another that is about 800 away and a third that is about 400 meters away (approx)

i can take out 3 ships out of a large convoy using this method by firing at the furthest ship first, waiting about 15 seconds then firing the second ship, waiting a few seconds more and firing the third shots. the hits almost always strike all three ships within about 12 seconds from the first hit to the last hit so zig zagging error is reduced this way because they have little warning.

by this time the escorts have wised up and it is time to get deep and get away and try again the next night. if you make good use of your torpedos you can claim 10 to 12 ships from a large convoy over the course of 3 or 4 days of stalking - shooting - evading - reloading (internals and externals) - stalking - and shooting again.

[raduz]

Originally Posted by Dantenoc

For an extreme example, imagine yourself following a paralel course to the target, and traveling at the exact same speed... under this scenario, you will observe no bearing change whatsoever no matter how long a time you keep watching the target. The computer will think that the target is stationary when in "reality" It is moving just as fast as you are.

In such a case, you can try to obtain the targets speed via hydrophone, counting the RPM. It is reliable and not affected by weather.

[P_Funk]

Originally Posted by raduz

In such a case, you can try to obtain the targets speed via hydrophone, counting the RPM. It is reliable and not affected by weather.

Only if you have a reference point for how many RPMs equal a knot and such. As I understand it its been altered many times and theres no standard chart for it now.

[raduz]

Originally Posted by P_Funk

Only if you have a reference point for how many RPMs equal a knot and such. As I understand it its been altered many times and theres no standard chart for it now.

sure it is. check here:

http://www.subsim.com/radioroom/show...ophone+hunting

Using the following equation you can track targets for longer times and distance to determine estimated speed:

Kilometers x 32.5 divided by minutes = knots


Example: 2.8 kilometers traveled x 32.5, divided by 13 minutes = 7 knots

[P_Funk]

Originally Posted by raduz

sure it is. check here:

http://www.subsim.com/radioroom/show...ophone+hunting

Ah but you see, until you made that there was none. I actually haven't seen that before. Very cool. I'll definitely give it a go.

EDIT. And alternatives to the 3 15 rules are many. I personally love the nomograph. Lets you take your raw range and time data and turn out a speed. Very useful for 1 minute calculations. Or long term ones too.

Also you should note that [1 knot = 1.852 km/h] or [1 km/h = 0.539 Knots] or [1 knot = 30.866 meters per minute]. With that in mind you could take any distance travelled and form an equation.

Remember that lovely triangle? The D on top, the S and T on the bottom? Speed is equal to Distance divided by Time. I just figured this one out.

(distance travelled in KM / time in minutes) x 30.866 = speed in knots.

Using von Zelda's example. (2.8/13) = 0.215*. That is the number of meters that are taversed in one minute.
0.215 x 30.866 = 6.6, rounded down. Thats a pretty accurate one I think. Unless a math guy can tell me I'm wrong, which I'm prepared for being a math moron myself.

[bert8for3]

Originally Posted by raduz

sure it is. check here:

http://www.subsim.com/radioroom/show...ophone+hunting

@raduz. Appreciate you mentioning that, 'cause I missed the thread, going to check that out for sure.

[raduz]

guys I am glad at least someone is interested in hydrophone hunting... I was afraid my work would be forgotten......

[bert8for3]

Originally Posted by raduz

guys I am glad at least someone is interested in hydrophone hunting... I was afraid my work would be forgotten......

Well, better late than never (my noticing it that is). I'been wanting to learn this for some time, as I find the hydrophone really adds to the immersion, but aside from telling bearing (more or less), I didn't have a clue about range or speed. Love yr +40pp tutorial/manual, btw, just flipped through at this point, but am going to study it properly.

[java`s revenge]

Ok here is my manner of calculating the speed.
Once i have read it on the ubiforum. Since then i use it always.

- Recogn the target.
- Set the crosshair at the beginning of the target.
- set on the stopwatch
- set it off when the crosshair is at the end of the target.
- take a look in you recognbook how long your target is.
- Calculate: time divided by the metres of the ship multiply the outcome with 0,1942.

Now you have the speed.

So for example a ship of 90 metres with a time of 30 secs

30 : 90 = 0,33 x 0,1942 - 0,06. So the speed of the ship is 6 knots.

For me this works great above all named manners.