Periscope Determining range??

[Kirk]

What is the best way to user your periscope to determine a target's range?

[Wildcat]

It's actually really simple, it's a very nice tool to use for attacks on surface ships..

Basically, raise the scope, zoom in on your target so it's nice and big. Next, get the center crosshairs in the middle of the target. It's actually not so important to get the vertical line lined up, but the horizontal line should be lined up with the waterline on the target. Now mark the contact and take a photo of it.

Go into the identification area in the periscope screen and determine the ship type and approximate angle. Now what you need to do is move one of the sides of the stadimeter so that the waterline on one side matches up with the top of the mast on the other side.

Once you've done that you'll have a fairly accurate solution. The more you zoomed in to take your picture, the more accurate your stadimeter estimate will be. It is VERY IMPORTANT that you line up the actual waterline on the hull of the target with the top of the mast. So if your periscope's horizontal reference line was off a little, that is fine, as long as you line up the waterline manually with the top of the mast, it will be accurate.

Generally you will have already gotten your contact on sonar, but the periscope is a good way to cross reference. If you want to do it old school style, you can forget about your sonar and just use some old fashioned uboat tactics (They can be found in the SH2 forums I'm sure.) for determining speed and generating a tma solution or best bearing to make a snapshot.

[Kirk]

Hey Wildcat. Thanks for the info. That is what I thought what to do but when I actually did the action I was getting readings 5000 to 10000 yards off when I compared to a radar range. I did check to make sure it was the right target picked out but who knows. Thanks again for the info.

[Wildcat]

If you line up the waterline exactly with the top of the mast it'll usually be accurate to within 2000 yards. That's the trouble with computer games, the resolution is not high enough, so a pixel movement of 1 or 2 pixels could represent a distance of 5km. That's why it's best to zoom in to maximum on targets when you take a scope picture.

[OKO]

damn ... my computer rebooted alone when I just finished to post some additionnal informations here
grrrr

So I will be short :
In fact, in DW, you must not exactly use the highest mast, but the highest structure !
Don't ask me why, but I'm sure it is like this in DW (tested hundreds times)
If you use the highest mast, you will always have shorter value than expected (except if the highest mast is as high as the highest structure ...) because mast are usually a bit higher than the structure, and sometimes MUCH higher
About use of stadimeter :
The smaller the ship, the closer to you he should be to work at stadimeter
sounds logical hey ?
But what I mean is you better work when your target is quite big in your scope.

Example : with a super tanker, you could work at very large distance, find an accurate range at 15 miles.
But if you work at a perry, you better wait to see her quite big at scope, or you will have real problems to find a correct range.
On a perry, you are going to find correct values at around 9 or 8 miles, and accurate values only from 7 miles.
Before that time, you will have at least ~30% of error, or more.

If you want to do it old school style, you can forget about your sonar and just use some old fashioned uboat tactics

you better use the TMA station here :
To have a nice target trajectory, take 3 or 4 photos, use stadimeter each time on them, then go to TMA station, and you could do here a VERY accurate TMA on your contact in less than 30 seconds : the easiest TMA you could imagine, same as with active contact (each track have a specific range you calculated with stadimeter, you just have to put the tick marks of the ruler on them, no range to find, you already calculated it !).
Even with only 2 tracks you could make it, but you better take 3 or 4 to have a more accurate course for your target.

For the KILO, using stadimeter + TMA gave you a fantastic combinaison to find very easily and very quick the course/speed of your target.
And it's way more easier than WWII old school !



Last thing : for the OHP, on the opposite of other platforms, the best mark to use is not the highest structure, but the black platform of the CAS radar, the highest mast.
Again don't ask me why, this is empiricism, I made tests to estimate the best I could the range of this supposed manned platform.
But except on OHP (...) on most military ships, the best upper mark is the highest structure.

[OKO]

Originally Posted by Wildcat

If you line up the waterline exactly with the top of the mast it'll usually be accurate to within 2000 yards. That's the trouble with computer games, the resolution is not high enough, so a pixel movement of 1 or 2 pixels could represent a distance of 5km. That's why it's best to zoom in to maximum on targets when you take a scope picture.

(try the highest structure, and not the highest mast, Wildcat, and tell me what you think about)
and the most annoying thing now is the roll of the ship !
when in high sea, its really difficult to put the d*mn lower mark on the waterline !
especially at long range, where it's just a pure waste of time to find an accurate range with this roll that prevent you to have an accurate mark set at waterline.
When some pixel could X2 the distance (especially at long range of course), you should take a lot of care to have a good picture, and you need to do it again and again until this mark is exactly at the waterline before going to stadimeter.

One other way is to "compensate" :
I couldn't take a clean picture because my ship is rolling too much =>
so i see my lower mark is ~5 pixel under the waterline => I just have to put the upper mark 5 pixel above the highest structure.
Much more easier to say than to do in fact ...

Last thing, very important
the earth is not flat (Hooo you knew it ?! )
And this is simulated in DW (ha ... did you knew that ?! )
So, if the target is far from you, you must put the lower mark UNDER the sea level, because the sea level here is NOT the waterline of the target.
So you have to make an evaluation of where is the real waterline of the ship.
This is mostly for small ship, like fregate, where freeboard is quite low on the sea.
Sometimes you don't even see the hull !
In that case, this mean anyway you are too far to make any accurate stadimeter measurment, so just wait the target close your ship.

[Wim Libaers]

Right. The stadimeter can be useful, but it will be very misleading if you use it according to the instructions in the manual.

I think it's a but silly in any case, to have this requirement of two specific points (waterline and top). The waterline isn't even approximately constant in reality for ships which can carry cargo.

It would be better to have the 3D reference image rendered as if seen through the periscope at the magnification setting you used. Adjust range and angle, and mark when the picture and the reference look the same.

[GunnersMate]

[quote="Wim Libaers"]I think it's a but silly in any case, to have this requirement of two specific points (waterline and top). The waterline isn't even approximately constant in reality for ships which can carry cargo.
quote]

90% of the time ships will be hull down anyway. Why cant we have a laser rangefinder?

[LuftWolf]

Originally Posted by Wim Libaers

90% of the time ships will be hull down anyway. Why cant we have a laser rangefinder?

Because lasers don't work very well at sea... at least not at the ranges that would make them useful.

[Wildcat]

They are also detectable and would serve the same purpose as sticking your radar up for a few sweeps.

[drEaPer]

I bet laser would work. There are lasers on the market made for the sea.
This fits into the same category: How can I use the Kilo periscope in the dark? Why does it has no light amplification?

[TLAM Strike]

Originally Posted by drEaPer

I bet laser would work. There are lasers on the market made for the sea.

Yea but warships got laser detectors to warn of attack.

This fits into the same category: How can I use the Kilo periscope in the dark? Why does it has no light amplification?

No space for the LLTV. I've read that most Kilos don't have it.

[OKO]

Originally Posted by drEaPer

I bet laser would work. There are lasers on the market made for the sea.
This fits into the same category: How can I use the Kilo periscope in the dark? Why does it has no light amplification?

Laser is active system
any active system could be detected
If it was known that subs use laser ranging, every potential targets will be riddled with laser detectors (easy to build and quite cheap) like every modern main battle tanks are, on the battlefield.
Sub must rely on passive here, active will just kill their stealth.

And yes, using the periscope of the KILO by night is a real challenge ...
spotting ennemy aircrafts, and even sea target, become really problematic.
fortunatly, they have good passive sonars and TMA station for sea target at night ... :|\