Stadimeter & range estimates....Choppy Waters!

[Keelbuster]

Manual targetters: How the $%#* do you get a decent range with the Stadimeter in anything but totally calm water?? I've been using the average technique - like take 3 readings and do a rough average, but in light winds I find my estimates bounce all over the place making it impossible to get a decent range. Without the target speed estimate (which I derive from three or more range estimates), I can't make a good shot.

Second, semi-related issue - how to determine target speed (forget bearing & range - just speed) with the hydrophone? In DW there's a DEMON analysis that one does to determine this. How to do it in SH3? I can line up a shot abeam by eyeballing the AOB, but the speed is hard to get right - an accurate measure by hydrophone could really help and eliminate the need to use the Stadimeter in rough weather.

Kb

[ParaB]

I always use the "optics stabilization" feature. I play with manual targetting and without map contacts updates but I'm not THAT masochistic to do so with the reticule bobbing all over the place in anything but calm seas.

You can't measure the speed of a target by hydrophone. You can either use the notepad in the UZO or periscope views to calculate a target's speed (you need to estimate the AOB and distance before and be stopped while taking the time for accurate data) or you can plot down the target on your map (you need bearing and distance), then connect the points and do the math.

I usually use the 2nd method since it's far more accurate for me.

[Heibges]

I use the MILS method as opposed to the mast hight method. Much quicker and easier. It gives you the range instantaneously.

There is a sound trainer for SH3 where you can determine speed by the hydrophone through listening.

I usually use the matching speed method, which is easiest if you have favorable conditions.

[Kpt. Lehmann]

I use the MILS method as opposed to the mast hight method. Much quicker and easier. It gives you the range instantaneously.

Could you explain this "MILS Method" Heibges?

[Heibges]

At a known distance, any object will appear to have a known length. I think each tick on the periscope is equal to 5 mils, but that is really unimportant. We'll just call each tick on the periscope a unit. The following table is for targets on a perpedicular course and a 0°AoB.

........................Range.............1200m... ........600m
C2 Merchant.............................6units....... ..12units
C3 Merchant.............................7units....... ..14units

I had a chart for all ships and ranges, but I accidently threw it away, and have been procrastinating on redoing it.

[jasonb885]

I use the MILS method as opposed to the mast hight method. Much quicker and easier. It gives you the range instantaneously.

Could you explain this "MILS Method" Heibges?

I am guessing it is this, but it doesn't explain how.

http://en.wikipedia.org/wiki/Angular_mil

:hmm:

[jasonb885]

At a known distance, any object will appear to have a known length. I think each tick on the periscope is equal to 5 mils, but that is really unimportant. We'll just call each tick on the periscope a unit. The following table is for targets on a perpedicular course and a 0°AoB.

........................Range.............1200m... ........600m
C2 Merchant.............................6units....... ..12units
C3 Merchant.............................7units....... ..14units

I had a chart for all ships and ranges, but I accidently threw it away, and have been procrastinating on redoing it.

Dude, you're my hero!!

:up:

Although, at 0 AoB isn't it a little late to shoot? More useful for convoy encounters I'd imagine.

I've found determining course and speed so I can setup a Fast 90 shot is more valuable than the actual distance, as the torpedos travel so fast that when you're close enough to actually get distance with the statometer you're within 4k anyway.

However, I suck at determining course...

[Keelbuster]

Matching speeds - i can't imagine doing this well without accurate range estimates. Yer moving along beside a merchant, trying to match AOB and speed, and trying to decide if your target is growing or shrinking in the UZO. I might have to opt for the periscope stabilization. I've been using WO estimates while on surface, which are TRUTH I think, and hence life has been good. But when at peri, there's no speed matching to be done, and it's all about the stadi and the hydrophone. I'm still kinda noobed. I'm going to look into the MILS method. Sounds good. Did they use it in RL?

Kb

[Heibges]

Right, you would actually shoot at probably AoB 5° or AoB 10°, so you will have to guesstimate a little the range, but it should get you in easily within 100m+/-.

The range is my final input into the TDC before shooting.

[Heibges]

To match speed first you must determine target course, and get on a parallel course yourself. Then it is easy. Unfortunately, less an less possible as more and more escorts have radar, and you can get close enough to the convoy. This method can only be used if you are on the surface.

Once you have to submerge, determining speed through change in bearing is much more complicated I thingk.

[Heibges]

I'm going to look into the MILS method. Sounds good. Did they use it in RL?

Kb

Hmmm. I know tankers used it to find range up to the Korean War, when they introduced the collateral rangefinder.

The Uboat Commanders Handbook stresses time after time the importance of being able to estimate range, and the same thing is found in U.S Army military manuals today.

I have found very little anecdotal evidense to say exactly how kaleuns did or didn't do it, but nothing else really makes much sense.

[Keelbuster]

Hmm.

If you can get instantaneous range through MILS at PD, then you can use the 3m15s rule to estimate speed. Then yer fine. I think.

Also, I haven't set range on TDC - I thought that was only to give you the timer till impact...

Kb

[jmr]

I'm a fan of this tip (http://www.subsim.com/phpBB/viewtopic.php?t=39271) in getting range in rough seas.

[don1reed]

The following table is for targets on a perpedicular course and a 0°AoB.

Heibges, I think you mean AoB of 90° if you mean perpendicular, like crossing the "T". AoB 0° = down the throat and AoB 180° = up the kilt.

jmr, thats an excellent table. I use a variance of that table by plugging in the ships length instead of masthead height (MHH) during choppy wx. Even tho the ship's bouncing around, it's length stays stable; but, the measurement must be taken when the AOB is between 60-120°. You don't have to be spot-on accurate.

Cheers,

[Keelbuster]

You know what - i've decided to fix my periscope/UZO. I like manual targetting, but damn - it's a bit far fetched to go to all these measures when we can just fix the damn thing; it can't have been this hard in real life! Imagine an RL Kaleun clickin' and cursin'. Not likely.

Thanks for all the help boys.

Kb

[Heibges]

That's right I'm sorry. I meant perpendicular course, bearing 0°, AoB 90°. You are using the MILS method also, which we were discussing above. Do you have a complete chart for this? I had one which I had scibbled in a notebook, which got thrown away before I could put it on the computer. I haven't gone on patrol in a while because I need to redo the chart before I do.

The one problem I have , and something that is very realistic and really hampered the uboat effort, is that in poor visibility I might not have 3:15 of visibility time. Also, being submerged, I am at the mercy of the convoy if they change course.

It's easy to see why the uboats were so much more successful on the surface than at PD.

I'm sure kalues did have extensive combat tables, similiar to what an artillery unit would have.

[Sawdust]

The one problem I have , and something that is very realistic and really hampered the uboat effort, is that in poor visibility I might not have 3:15 of visibility time.
I've switched to estimating the speed of the ship by only waiting half of the time of 3:14, that is 1:37 (because of impatience rather than lack of visibility time :oops: ) Just double the result to get the same answer. So far, the extra inaccuracy has been OK, but I am using automatic map updates which makes it easier.
I suppose one could get a really rough guess of target speed by halving the time again (and again? :hmm: )

Is there any chance in SHIII of estimating a ship's speed by the size of its bow spray? That would be cool.

[Keelbuster]

the quality of your estimate should increase with time! If you keep halving it, eventually you'll have noise!

Kb

[don1reed]

Ships length past the vertical graticule / seconds x (3600/1852) = speed.

caveat: ship AOB should be between 60 & 120°, and the sub setting still or No faster than 1 kn.

i.e., T2 = 152.7m / 40 sec. x 1.94 = 7.4 kn.

I never worry about 'range' if the target fills half the scope @ x6 it's close enough for a kill. Speed & AOB are the only things of concern.

[jasonb885]

Ships length past the vertical graticule / seconds x (3600/1852) = speed.

caveat: ship AOB should be between 60 & 120°, and the sub setting still or No faster than 1 kn.

i.e., T2 = 152.7m / 40 sec. x 1.94 = 7.4 kn.

I never worry about 'range' if the target fills half the scope @ x6 it's close enough for a kill. Speed & AOB are the only things of concern.

I should've written all this down last April when these kinds of questions were more common.

Thanks for posting on this! (Again?) :)

[greyrider]

jason, one decree is equal to 17.7 mils.

if you saw the GTA (graphic training aid) that i put as a pic in the tread sh3 grid protractor, you will see a square protractor, i and many use for indirect fire, and land navigation.

the outside edge is in mils, there are 6400 mils in a 360 decree circle.

there are 360 decrees in a circle.

the math to find how many mils in one decree is,

6400 / 360 = 17.7 mils.

check this out.

http://www.maptools.com/products/UTMGrids.html

using mils is alot more accurate and precise than decrees.