calculating speed in sh4?

[flakmonkey]

Ok this may seem a bit of a silly question but just how the heck do you calculate speed in sh4 (using the default/stock method)?

I Id the ship with the manual, use the stadimeter tool to get the range, input the angle on bow using the dial but when i goto the speed part of the tool i keep getting a message saying "cannot estimate speed, need more data", what more data could possibly be needed??

Ive even looked in the game manual (a first for me!) and i seem to be doing everything by the book but its just not working!! :damn::damn::damn:

[BillBam]

If you are using the Stadimeter to calculate speed you need to take two readings far enough apart to give a good solution. The TDC will calculate this info based on the gap between the two readings, only using one will not work.

You can also calculate from the Nav Map by marking target position, wait 3 minutes (3.25 if in metric) and make a second mark. Using the compass calculate the distance between points and divide by 100 to get speed. For example if the distance is 1000 yards the speed is 10 kts. You can then enter this info maunally into the TDC.

[convoy hunter]

That's an easy one.
By using the map count how many meters the target travels for 30 seconds.
Then divide it by 1000 multiply by 120 divide again by 1.85 and you got speed in knots. For practise test it at yor own sub go at 5 kts steady speed and try if you can get a close solution to your speed.:salute:

[razark]

You need a second range/bearing.

They need to be separated by a certain amount of time, maybe 10 seconds.

They also need to be recent. You can't take two range/bearing readings and wait five minutes to calculate speed.

[flakmonkey]

Ahh thanks, the manual doesnt bother to mention the need for a second range reading! Im so used to sh3 and just starting a little timer to calculate the speed:up:

[Fish40]

Flakmonkey, you could also see here: http://www.subsim.com/radioroom/showthread.php?t=148431&highlight=ship+lengths I calculate speed by timeing a vessel crossing the periscope 0 bearing wire. If you know the length of the vessel, calculateing speed is a piece of cake!

[flakmonkey]

Nope still doesnt work! Ive taken the range 30+ times and entered the aob again and again and still i get the message about needing more data when i try to get speed!

I cant even use the stopwatch to do it manually, i click on it and nothing happens, short of finding a real life stopwatch im out of ideas, i knew it was a mistake to reinstall this s**t!
Im heading back to shV.

[tomoose]

The following is a generic how-to list. There may be some debate about the order of the first few but it works for me.

1. ID target
2. Check target in ID book
3. Adjust AOB (click on red send to TDC button)
4. Take first range reading with stadimeter (click on red "send to TDC" button)
5. Wait at least 10 seconds
6. Take second range reading with stadimeter (click on red "send to TDC" button).
7. Click on Speed button, click on calculate button, (click on red "send to TDC" button).

This will produce a response in the dialogue box stating the targets' speed and course. Adjust AOB to match the stated course if required (use the PK to verify i.e. the PK target course indicator should change to match the AOB you input if you're doing it correctly).
Repeat the process as required.

Note: if you are not clicking on the red "send to TDC" button after each step then nothing is being entered into your TDC ergo "no data". You MUST send the info to the TDC.

This is NOT an exact science and you should not expect it to be. It takes a bit of practice. Conversely you could go with the Dick O'Kane method (do a search of the forums) which apparently simplifies the whole approach and takes the "computer" part out of the equation.

The stopwatch works fine for me, just click on the top winding 'button' of the stopwatch graphic to start and click it again to stop.

Hope this helps.

[flakmonkey]

The following is a generic how-to list. There may be some debate about the order of the first few but it works for me.

1. ID target
2. Check target in ID book
3. Adjust AOB (click on red send to TDC button)
4. Take first range reading with stadimeter (click on red "send to TDC" button)
5. Wait at least 10 seconds
6. Take second range reading with stadimeter (click on red "send to TDC" button).
7. Click on Speed button, click on calculate button, (click on red "send to TDC" button).

This will produce a response in the dialogue box stating the targets' speed and course. Adjust AOB to match the stated course if required (use the PK to verify i.e. the PK target course indicator should change to match the AOB you input if you're doing it correctly).
Repeat the process as required.

Note: if you are not clicking on the red "send to TDC" button after each step then nothing is being entered into your TDC ergo "no data". You MUST send the info to the TDC.

This is NOT an exact science and you should not expect it to be. It takes a bit of practice. Conversely you could go with the Dick O'Kane method (do a search of the forums) which apparently simplifies the whole approach and takes the "computer" part out of the equation.

The stopwatch works fine for me, just click on the top winding 'button' of the stopwatch graphic to start and click it again to stop.

Hope this helps.


Thanks Tomoose, its amazing how frustrating it is when you think youre doing everything right and nothing works, finally sorted it though:up:

[Excelsior82]

I cant even use the stopwatch to do it manually, i click on it and nothing happens, short of finding a real life stopwatch im out of ideas, i knew it was a mistake to reinstall this s**t!

Uh.. ?
Are you running v1.4 (any mod ?) ?

I'm using stock 1.4 and when I click on the button on the top of the device, I hear it ticking regularly and a set of blue hands that moves along the time.

I use it a lot to know when I can emerge after having spotted an aircraft coming in my way.

[Platapus]

I do use a separate stopwatch as it enhances my role playing. But you can get a cheap digital timer for about 5 bucks these days, or just use your watch.

Here is another quick way to get the speed.

If you know the length of the target ship in meters.
If you can get a good look at the side of the target (AoB 30-150)
If the bearing to the target is +/- 20 degrees from 0/180

1. Lock the periscope to the target. The lock function places the periscope hairline approximately in the center of your target. Close enough for our purposes.

2. Get your timer ready and when ever you are ready to time, unlock the periscope but don't move it.

3. Stop timing when the butt of your target crosses the hairline.

Speed in Knots = Length in meters/time in seconds.

This is a variation of the original, and more accurate:

Speed in knots = 1.94 x Length in meters/time in seconds routine. The locking method just gives you the speed faster and is accurate enough for 1500 meter and shorter shots.

[les green01]

i use my stop watch on my cell phone,also the calactor as my math sucks

[Phantom II]

Anyone know why SH4 and TMO doesn't specify ship length in the Recognition Manual? Otherwise you could line up the vertical line of your periscope with the front of the ship, start a timer, and measure the time it takes for it to get to the rear. Now if that distance is a known, you can divide it by the time taken to get a value in m/s. And to get a rough knot value, you simply multiply that by 2. (i.e 10m/s = 20kts)

[LGN1]

Is it possible to use the 'calculate speed'-feature also in combination with the active sonar, i.e., sending the range and bearing from the sonar to the TDC twice and then asking somehow the speed and course? I tried it, but I could not do it :hmmm: Is it just me or does it not work?

Cheers, LGN1

[tomoose]

Phantom: The ship's length isn't in the ID book?? I'll have to check that. I was under the impression it was (although I'm always looking at the max speed and draft figures). I thought the length was written in there (I know it used to be along the bottom of the book 'page').:-?

LGN1: That's a valid question and on the face of it, it should work given that the active ping has a button to "send to TDC". Having said that I've found the active sonar to give very rough results so even if it did work I'm not sure the speed would be calculated correctly. Additionally if there's ANY warships near your target the ping would be like sending up a flare, LOL.

[Fincuan]

No need to worry about pinging with actice sonar in SH4. At least in the past the AI didn't react to it at all, and I'm not aware of any mods fixing this. Active sonar is very precise when used correctly, but iirc with incorrect procedures it is possible to get range readings that are completely bogus. Unfortunately it's been a long time since I used it so I don't remember the exact steps anymore, but playing with it a little in a training mission should reveal the correct and incorrect ways pretty quickly.

[Fish40]

This little mod adds ship lengths: http://www.subsim.com/radioroom/showthread.php?t=166096

I use it with no problems with RFB.

[BillBam]

I use the active sonar pinging for blind attacks all the time and find it works very well, especially when you fire at less than 2000 yds (have hit targets over 3500 yds but it generally takes a good spread to get one or two hits.) I always check the attack map to see how my solution is in realation to the target on the map and right after a ping and send to TDC the white X is almost always right on.

[tomoose]

Fincuan has a point in that the AI doesn't seem to react to active sonar (although sometimes I'm not so sure LOL). To clarify my earlier comment, if it wouldn't be done in real life (i.e. using active sonar with warships around) then I don't do it in the game.
:salute:

[Fincuan]

I agree tomoose, although even in real life you could probably have gotten away with a few carefully placed pings if the escorts were pinging too at the same time. Remember that an attack using the active sonar was THE way to do it in the pre-war US doctrine as it was thought a periscope would be too easy to spot.

[tomoose]

....but pre-war and at-war are drastically different. I'd guess not many skippers risked active sonar with warships around but I don't have any stats to back that up, that's just my personal take on things. How would you know when the enemy is going to ping? In the heat of battle you could probably risk it but then again the whole point of the sub was stealth and being "a hole in the water", why advertise? Ultimately it would be the skipper's call to make, balancing the risk to his ship and crew versus achieving the aim of his mission.

[don1reed]

Tnx for the "ship's length mod" tip, Fish40:salute:

Up til now I had been measuring the MHH with a set of dividers and walking the length of the ship in the ONI. (ratio & proportion)

Nice mod, tnx agn.

Cheers,