Actually, I originally started this thread with a question about the maximum range displayed on the TDC (note the thread title/subject). It got severely derailed when someone noticed your straight-key, to the point where someone looking at the thread would think the on-topic posts were actually off-topic.

Not that I mind the derailing -- all the info about contacting submarines via radio is really interesting. I had no idea one could do that. :D

nomad_delta

Indeed thats why Ive layed low now :smug:

Ill contact Puster directly for more info someday :up:

Feel free to do it here, as I'm finding it all quite fascinating. Maybe I'll have to study up and get my ham radio license. :p

Although I would still be interested in hearing how other people determine range/plot target courses at ranges farther than 9000 yards with map contact updates disabled and without using the WO.

nomad_delta

nomad,

did some tests a few days ago but forgot to post the results here :oops: The TDC is NOT limited to 9000 yards, because with extended horizon and crew sensors I see it tracking ships at 20000 yards in AUTO mode. The problem seems to be that manually using the stadimeter you don't get correct readings farther than 9000 yards, i.e. the problem seems to be in the stadimeter, not in the TDC.

I must say however that the Zeiss optics attack persicope installed in german U-Boots in WW2 had also the same superimposed image system for rangefinding and the absolute limit of use for the device was around 10000 metres. So even if this is just a bug, it seems to be historically accurate :hmm:

That's really good info; thanks Hitman!

So if the stadimeter was (both historically and in-game) not useful beyond 9k-10k meters, how did real US subs estimate ranges (and thus plot and estimate course/true bearing) on targets farther than 9k meters away? If that info's not readily available, I'd be happy with hearing how you guys do it. ;)

nomad_delta

Basically through radar :) and when not available, they followed the changes in bearing to have an overall idea of the heading and try an intercept course. Note that at high ranges, if intercept is not possible, it will be soon aparent to an observer on the sub.

Also, when you only see masts above the horizon its is very difficult to use the stadimeter because you can't see the waterline for reference in the split image (Horizon is at some 8000 yards at peri depth, and anything beyond that you have partially hidden heigth). Instead, you can estimate, based in the type of masts, the nature of the enemy vessel and make a rough guess about how far it must be for you to see only the masts. :yep: Then when you get under 9000 you can start the plot with more precission. Above that distance, all you really need is a general heading of the enemy for trying to intercept...details will be clearer when closing in:up:

Why doesn't the watch officer give you range to the ship you're looking at via binnocs instead of always the nearest (inc life boats). It would be a very simple piece of coding....

One possible reason is that you would not be able to determine range through biniculars alone. If you could there would be no need for a stadimeter (or a "plot team" for that matter).


JCC

Its an approximate range i'd be lookinng for, e.g:

Capn: Looks like a fully laden tanker, how far is she ?
WO: I'd say about 2000 yards.
Capn: Mmmmm....and what about that escort to her stern.
WO: Definately nearer, say 1300 yard.

I imagine such conversations existed.

Actually, they could. They used the ship's position vs the horizon. The horizon distance is known for different heights on the sub (bridge, periscope shears, etc). They could look up the target in the recognition manual and compare. If the target was hull down, it was past the horizon by an amount equal to the horizon distance from a height equal to the point "cut" by the forground horizon. If the target was closer than the horizon, then the target would be in front of the background horizon line, and you'd subtract the value. of the 2 horizon distances.

Rough, but it works.

tater

How does range estimate influence your intercept course calculation?

I would understand if you were saying you need distance to estimate speed... but if target speed and heading are known, distance can be anything you want and it won't effect the result of your constant bearing intercept formula.

If the ship was hull down, in the haze, and just about over the horizon, how in the world would they have been able to accurately identify it?

Now I agree that the distance to the horizon from the bridge was an approximately known value, and if all you could see was the tips of the mast, you could make a good guess at the distance (Dist to Horiz. + a little bit more), but having spend a little time at sea I find it very very hard to believe that you could accurately id any ship at any kind of distance in anything but perfect conditions, let alone get a reasonable estimation of range. Put in some weather or a decent chop and you are out of business.

Plus, to the best of my fading memory, none of the hundreds of patrol reports I have read ever made any reference to anythig like this.

Much more likely they would use the periscope or TBT for that sort of thing.

JCC

Certainly for large warships, the masts and upper superstructure tend to be unique for each class, so that can be a large clue. I dimly remember reading something about one of Japan's major warships being attacked by a sub, and the way they tentatively identified it while it was still hull-down was the mast and 'pagoda-like' superstructure.

At a distance, you don't have to get a firing solution, you just have to have a solution accurate enough to put you on a collision course, and you refine your solutions as you go, until you hopefully have a good solution. By that time, you'll hopefully have a better ID on the target, but that isn't STRICTLY necessary, though it does make it more likely that you will hit.

A solution that is 'good enough' for interception can be off by a significant amount in speed and course, but it will point you in the right direction. You don't *NEED* an accurate range or ID for that, you just have to keep the target at a constant bearing (with the target getting closer, obviously).

They know the height of the periscope (surface and at PD) and the TBT as well.

http://members.spinn.net/~merrick/St...e_table_sm.jpg

The US Navy thought it was possible, this is one of the first pages in ONI 41-42 on jap warships.

<shrug>

tater