odd speed reading

Hi guys,

I need your help.

I'm playing GWS SH4, and loving it, but for some reason when I calculate my target's speed through the perisocope notepad it will work sometimes - showing values of say 4 or 5 KTS for a merchant, but other times will show 45, 80 or 90 KTS values. What the hell?

Am I doing something wrong, or is this a bug.

Thanks for your help.

[Morts]

i s'pose you mean GWX SHIII (3)?
and dont worry, its a bug you're not doing anything wrong

[raduz]

Originally Posted by obliviongate

Hi guys,

I need your help.

I'm playing GWS SH4, and loving it, but for some reason when I calculate my target's speed through the perisocope notepad it will work sometimes - showing values of say 4 or 5 KTS for a merchant, but other times will show 45, 80 or 90 KTS values. What the hell?

Am I doing something wrong, or is this a bug.

Thanks for your help.

depends on weather (rough seas make stadimeter measurement almost impossible) and on AoB (stadimeter works best when the targets movement is perpencicular to your position: 90 degrees). otherwise, I would recommend you to use hydrophone to get the speed.

Thanks for that. I wonder why it hasn't been patched.

And by the way, when GWX comes out for SH4 i'll start playing it!

[Platapus]

There are many reasons why your speed calculations are inaccurate and only a few of them are under your control.

The accuracy of your range calculations will have a massive impact on your speed calculations.

Anytime I get a merchant running at 50 knots I do the following

1. Triple-check your ID. I can't tell you how many times I have gotten the exact stadimeter reading of the wrong mast height because I was "close" in my ID. Measure the mast as it is in the recognition manual not to the top of any flag mast!

2. Redo your stadimeter collection. You can pause the game if you need help in aligning up the lines but note that the further the ship is away from you the less accurate the stadimeter (or more appropriately, the less accurate your placement of the index line) will be. For ships a long distance away, I prefer the 3:15 technique and wait until the ship fills up a goodly portion of my scope view before using the stadimeter.

3. As I recently learned from fellow posters way smarter than I, the speed calculations using the chronometer measures the relative speed between your sub and the target. This I was unaware of.

So if you are steaming on the surface at flank speed (18 knots) and your target is steaming toward you at 9 knots the relative speed will be 27 knots. Pretty fast for a merchant but no software bugs caused this. It is operating as designed. So if you want really accurate chronometer readings you have to be stopped.

Also, and this I have not confirmed, (any smart guys out there?) that the chronometer method assumes a 90 degree track or AoB.

The chronograph speed function measures the apparent angular displacement over time and factoring your range input does the simple sine trig calculations. This works great as long as you have a right triangle – AoB = 90 degrees.

If your target is heading straight toward or away from you, you will find the chronograph speed calculations to be inaccurate as the apparent angular displacement is a lot less.

The further your target track is away from a 90 degree track relative to your position the less accurate the speed calculation will be, as the program is assuming a right triangle and the actual track is not.

Does anyone know if the SH3 chronometer speed calculation takes into account AoB?

Anyway, there are many factors that make the measurement of speed of your target difficult and inaccurate regardless of any software bugs. I find speed to be the most challenging calculation I have to make with my manual targeting and I guess that is pretty realistic.

I think that many real life submarine captains used their judgment based on what the water looked like at the stern (estimating speed based on bow wave is more difficult and easier to misinterpret.

Good luck with it

That was so useful. Thanks for that post.

I had suspected that the bearing angle and my own speed might have had an impact.

[Dantenoc]

Yes, the "notepad" method for measuring speed does take into acount AoB, so at first instance, you shouldn't really need an AoB of 90 degrees, but in fact should be able to work with any AoB. Nevertheless, limitations on how the trigonometric functions themselves behave in the real "math" world make them very susceptible to errors for AoB's which are significantly different from 90 degrees.

So long story short: Theoreticaly, you should be able to cope with any AoB, in practice, you get better results with an AoB that is close to 90 degrees.