Which would you say is the most effective method of gathering target speed?

[Paul Riley]

Good day all.
Quite a simple question really,which would you say was the most effective method of gathering target speed?.As those of you who play with manual targetting will know this is probably the most important phase of preparing for an attack,for if the torpedo speed is even 1kt too fast or slow this could be all it takes for a torpedo to hit or miss.
Now I would consider myself a 'good' player and have more hits than misses,yet there are those times when you miss by a cat's whisker,usually experienced in heavy seas due to the unpredictable nature of the waves on ship speed.
Personally I prefer the 'match target speed' method,where you track a target (surfaced) on the visible boundary for a set time,usually 30mins is sufficient,dropping or increasing speed a knot at a time until you match the speed of your target,giving you a pretty reliable method.I really dont like the 3 min 15 secs method,it doesnt feel natural to me,and sort of seems inaccurate,but that may just be me.The fixed line method is really good but I forgot the formula that is used to aqquire speed (any reminders here would be great),and the submerged method where you count the rpms of the screws would be VERY useful in heavy seas whereas the other methods wouldnt be too reliable,plus the submerged method would become more important to learn as the threat from radar and planes increases.
So,if you could describe the methods you use and any further info you can provide relative to this thread that would be great,and could also help some of the newer players (we were all there once,and what a learning curve this game was)

Cheers :salute:

[GoldenRivet]

What i did:

I used an online time speed distance computer. I entered a series of speeds and the had the computer calculate the amount of time it would take the ship to move one of it's own boat lengths. i then entered the results into a small hand made manual.

so what you have is

TYPE: LARGE TANKER

TIME:......................SPEED

0:20.........................18KTS
0:23.........................16KTS
0:26.........................14KTS
0:30.........................12KTS
0:36.........................10KTS

and so on and so on

it was time consuming but i made this chart for every merchant ship class and every capital ship class.

the next thing i did... in game i would come to a dead stop. put the periscope cross hair in front of the target. when the bow touched the cross hair i would start my stopwatch... when the stern crossed the cross hair i would stop the stop watch.

if the observed "traverse time" was 30 seconds... i could look in my manual and see that the approximate target speed would be 12 knots.

when in doubt, i add about .5-1.0 knots.

this is an accurate speed computation in 95% of the situations i find myself in and works on most AOB angles greater than 45 degrees and less than about 135 degrees.

there is a formula for this "traverse time" method

but i dont recall it

i think it is

ships length / time x 1.3 = speed

something like that

someone else may know it

[TorpX]

I worked out this formula for speed estimation:

Vt = .59 Tl / t + Vs * (sin Abg / sin Aob)
where:
Vt is target speed, in knots

Tl is target length, in feet

t is time, in seconds

Abg is bearing angle, in degrees

Aob is angle on the bow, degrees

Vs is sub speed, knots

Note that I define Abg as bearing angle, not relative target bearing. This is because the sine of angles between 180 and 360 deg. are negative and will give the wrong answer. If the relative target bearing is between 180 and 360, the "bearing angle" must be measured from the bow going counter-clockwise. Note also, that at relative target bearings of 0 or 180 deg., the last term becomes 0, and one need not know the Aob. The same goes for a sub that is not moving. Similerly, if the sub is on a parallel course, the ratio (sin Abg / sin Aob) becomes 1.

Also, as before, if viewing the port side of the target from port side of the sub, or starboard side of target form starboard side of sub, then subtract the sub speed. (This would mean you are heading in opposite direction of target.)

The trig terms are needed to acount for your sub's speed relative to the target's course. The 2nd term drops out when the target is at 0 or 180 degrees.



Normally, I just plot multiple points and do the math. I feel getting a good number of points is important to fair out the errors of range estimation. The above formula works, but requires estimating the AOB, while plotting requires estimating the range. I guess it is a matter of which you prefer.


Edit:
I don't know which is most effective. There was discussion of whether this was a legit method in the SH4 forum. It seems the USN did not use it, but plotted instead. I think this would be better in RL, as many targets were not correctly ID'd.

[GoldenRivet]

here is the formula i have been using all these years.

1. Start the stopwatch when the ships bow touches the periscope's vertical cross hair. (make sure you are stopped if possible)

2. Stop the stopwatch when the ships stern crosses the periscope's vertical cross hair.

3. make a note of this "Traverse Time"

5. length of ship as recorded in the recognition manual divided by "traverse time" multiplied times 1.94 = target speed in knots

take more than one measurement if you can

[yubba]

here is the formula i have been using all these years.

1. Start the stopwatch when the ships bow touches the periscope's vertical cross hair. (make sure you are stopped if possible)

2. Stop the stopwatch when the ships stern crosses the periscope's vertical cross hair.

3. make a note of this "Traverse Time"

5. length of ship as recorded in the recognition manual divided by "traverse time" multiplied times 1.94 = target speed in knots

take more than one measurement if you can Just like the man said 1 meter/sec=1.94 or 2 knots and for you yanks 1ft/sec= 0.592knot

[frau kaleun]

Which would you say is the most effective method of gathering target speed?

Reading it off the notepad has always worked for me. :yeah:




:shifty:




I'll get my coat. :O:

[yubba]

Reading it off the notepad has always worked for me. :yeah:




:haha::har::doh: whus tat




I'll get my coat. :O:
:up::up:

[Paul Riley]

here is the formula i have been using all these years.

1. Start the stopwatch when the ships bow touches the periscope's vertical cross hair. (make sure you are stopped if possible)

2. Stop the stopwatch when the ships stern crosses the periscope's vertical cross hair.

3. make a note of this "Traverse Time"

5. length of ship as recorded in the recognition manual divided by "traverse time" multiplied times 1.94 = target speed in knots

take more than one measurement if you can

Simple and effective,I like it.Cheers :up: . I also like your log book idea,I may do this myself.I like to record everything,and even have a notebook for all known shipping lane co-ordinates I have encountered in the game.
Thanks also to everyone else,appreciate it.
Any thoughts on the submerged method?

[yubba]

just pull the plug, hire monkey to put it back.

[Woolfman]

[QUOTE=Paul Riley;1706712]Good day all.

Quite a simple question really,which would you say was the most effective method of gathering target speed?.I really dont like the 3 min 15 secs method,it doesnt feel natural to me,and sort of seems inaccurate,but that may just be me.

So far the 3 mins. 15 secs. has worked great for me! I call it the KISS method! :O:

K eep
I t
S imple and
S tupid

...IMHO i think we have to use what we feel is right. Ultimately what really matters is end results. TONNAGE:arrgh!:

[Sailor Steve]

I call it the KISS method! :O:
You and forty thousand before you, going back at least thirty years.

[Paul Riley]

[QUOTE=Paul Riley;1706712]Good day all.

Quite a simple question really,which would you say was the most effective method of gathering target speed?.I really dont like the 3 min 15 secs method,it doesnt feel natural to me,and sort of seems inaccurate,but that may just be me.

So far the 3 mins. 15 secs. has worked great for me! I call it the KISS method! :O:

K eep
I t
S imple and
S tupid

...IMHO i think we have to use what we feel is right. Ultimately what really matters is end results. TONNAGE:arrgh!:

I fully agree,after all,trying to work out complex maths while engaging a fast moving target is not very practical is it.Personally,I think the 'match your speed to target speed' is one of my favourites,and is fairly quick.Just becomes a bit tricky in rough sea :yep:

[Snestorm]

[QUOTE=Woolfman;1707076]

I fully agree,after all,trying to work out complex maths while engaging a fast moving target is not very practical is it.Personally,I think the 'match target speed' is one of my favourites :yep:

Agreed.

[Paul Riley]

Can someone just briefly describe how the 3 min 15 secs method came about?,what is the formula for it?

[Obltn Strand]

Can someone just briefly describe how the 3 min 15 secs method came about?,what is the formula for it?

This is on the move version.

Speed should be set to slow.

Take bearing and range of the target. Use watch officer if you will as he is very skilled in estimating ranges.

Start stopwatch.

Quickly hit F5 and mark your u boats position. Now you have 3 min 15 sec to do next phases.

Check u boats true course and adjust bearing. For example true course is 220 and targets bearing is 40 so target is 260 relative to north.

Measure distance and mark target position.

When 3 min 15 secs is closing repeat from quickly hit... to mark target position.

Measure the distance between two points and every 100m equals 1knot.

Now you have speed of the target as well it's course.

[Paul Riley]

This is on the move version.

Speed should be set to slow.

Take bearing and range of the target. Use watch officer if you will as he is very skilled in estimating ranges.

Start stopwatch.

Quickly hit F5 and mark your u boats position. Now you have 3 min 15 sec to do next phases.

Check u boats true course and adjust bearing. For example true course is 220 and targets bearing is 40 so target is 260 relative to north.

Measure distance and mark target position.

When 3 min 15 secs is closing repeat from quickly hit... to mark target position.

Measure the distance between two points and every 100m equals 1knot.

Now you have speed of the target as well it's course.

No no,you misunderstand me here,I KNOW how to use the 3min method,I was just interested in how the 3min 15 sec method was developed,where does the 15 secs come into it? etc.
Hope you follow me now :yep:

[Friede Rösing]

yes

[Flaxpants]

No no,you misunderstand me here,I KNOW how to use the 3min method,I was just interested in how the 3min 15 sec method was developed,where does the 15 secs come into it? etc.
Hope you follow me now :yep:

The 3min 15 sec method applies when you are working with Meters. Other than that the principle is identical.

[Obltn Strand]

No no,you misunderstand me here,I KNOW how to use the 3min method,I was just interested in how the 3min 15 sec method was developed,where does the 15 secs come into it? etc.
Hope you follow me now :yep:

The 3min 15 sec method applies when you are working with Meters. Other than that the principle is identical.

I see.

Well Flaxpants said it here. It's a meter thing.

Every 100m target travel during 3 min 15 sec equals one knot. Time really is irrelevant. Other than 3:15 just requires more complex mathematics.

[Paul Riley]

I see.

Well Flaxpants said it here. It's a meter thing.

Every 100m target travel during 3 min 15 sec equals one knot. Time really is irrelevant. Other than 3:15 just requires more complex mathematics.

Better the devil you know eh,I'm not gonna start messing around with A grade mathematics (I HATE maths!) just to aqquire a bloody ship's target speed ;)
Its worked all these years,why try to fix something that isnt broke etc
Cheers.

[Canovaro]

I always use the nomograph on the F5 map in GWX. To me that is the easiest method by far.
I'm surprised I seem to be the only one using it??

:hmmm:

[Obltn Strand]

Nomogaph is more useful against fast moving targets. After 3:15 good firing solution may be lost.

[sublynx]

I keep experimenting with fixed wire, counting RPM's, nomograph, 3:15 method, notepad and sometimes just looking at how high the wave of the keel goes and guessing from that. If I have the time I might have different estimations from different methods.

[Snestorm]

My most common method, is just my best educated guesstimation.
Although the fastest, it's far from the most effective, but I like it.

[Canovaro]

Yeah Raduz made this outstanding RPM sheet and a hunting tutorial to go with it. But this RPM sheet is useless since GWX2 because all the ships changed.
I wish I won a milion and not need to go to work anymore.
Now if you all pay me a million, I promise to make a new Hydro RPM sheet for all to enjoy.
:yeah:

[Pisces]

Agrees with Canovaro.Since the RPM-knot relationship tables went out the window after GWX 1.0something it is not to be used anymore. Raduz modified the soundfiles and/or the configs for each ship. But feel free to count anyway. You might be able to make the mod compatible again.

Why 3 minutes and 15 seconds, or actually 194.4 seconds? Well, the idea is you measure the amount of hundered meter steps (of the ruler) in that period, and that is the amount of knots. In that time, 1 knot has moved 100 meters.

100 meters/ (1852 meters/3600 seconds)

or

100 meters * (3600 seconds/ 1852 meters)

[Gerald]

:salute: