Maximum range on TDC

[nomad_delta]

Has anyone else noticed that the TDC has a maximum range of about 8990 yards? I've spotted a merchant about 20k yards away (according to my cheating WO) on a very clear night and was trying to ballpark guess its actual range with the stadimeter, but it keeps entering "8990" for the range.

What's odd is that the 'range' field on the TDC has FIVE digits, so it seems like it should be able to accept numbers higher than this.

I guess it doesn't matter terribly much, but it pretty well eliminates the use of the stadimeter to make range estimates from far away when trying to plot a target's course and figure out an intercept.

How do you guys plot courses on very-far-away targets and determine your intercept paths? (Assuming you don't have radar, which I currently do not)

nomad_delta

[SteamWake]

Id make a note of his heading and speed and plot an intercept course.

I have never used the TDC as an aid. Usually I start planning from much much further out.

[nomad_delta]

But how do you get heading and speed when all you can see is a blur on the horizon? (I guess I also should have specified that I'm playing with map contact updates turned off...)

nomad_delta

[Puster Bill]

But how do you get heading and speed when all you can see is a blur on the horizon? (I guess I also should have specified that I'm playing with map contact updates turned off...)

nomad_delta

Using the Watch Officer isn't cheating: It's his friggin' job to tell you bearings and distances.

What you need to do is build yourself a Submarine Attack Course Finder/IS-WAS. Here is the link where you can download it, along with the instructions:
http://www.subsim.com/radioroom/showthread.php?t=106923
Print it off on cardstock and inkjet transparencies, then put it together.

Here is what mine looks like:

Front:
http://img396.imageshack.us/img396/9431/picture027rl0.jpg

Back:
http://img396.imageshack.us/img396/8539/picture026bb9.jpg


Once you've done that, you can use the SACF/IS-WAS to find the true course and speed of a target given two range/bearing observations. You can also use it to plot an intercept course, and you can use it to find the AOB of the target once you are getting ready to shoot.

I *HIGHLY* recommend using it. It works just as well as doing the calculations manually, and much better than just 'guesstimating'. It's also pretty cheap, less than $10 or $15 US in materials to make several of them.

It also has the advantage of being authentic: It is what real US sub commanders (actually, probably someone in the tracking party) used to determine things like course, speed, and AOB of an enemy vessel.

[SteamWake]

Nice job on that Puster Mine looks like a 5 year old put it together LOL.

BTW who the hell still uses a straight key ? I bet you only use it to tune the rig :p

[Puster Bill]

Nice job on that Puster Mine looks like a 5 year old put it together LOL.

BTW who the hell still uses a straight key ? I bet you only use it to tune the rig :p

BZZZT! Wrong answer. I do 95% CW, and I've only ever used a straight key. Straight keys are the best, because it allows your natural fist to shine through.

I love having a QSO with someone using a vibroplex or a keyer at 20 wpm, then casually mentioning that I'm using a Chinese Army straight key. I can do between 18 and 20 wpm comfortably for a ragchew, and probably 25 or so for a contest type exchange.

Of course, I learned Morse in the Army, and spent 8 hours a day for 4 years copying it (ex 05H10 EW/SIGINT/Morse Interceptor), so I sometimes actually have dreams in CW.

[Puster Bill]

Just for you SteamWake, here is a short video of me using my straight key:

http://www.youtube.com/watch?v=rHM9kWSvGIs

[nomad_delta]

Using the Watch Officer isn't cheating: It's his friggin' job to tell you bearings and distances.

Agreed, but how on earth does the WO figure out exact distance to a target that we haven't even identified yet (and which is too far away for me to have any hope of identifying...)

I guess I also don't like relying upon the WO as my only means of determining distances, 'cause he'll only tell me the range and bearing to the closest target... which means if there happens to be a life boat or something sitting closer he'll keep telling me about that instead. :p

I don't mind having the WO do his job, but I'd at least like to know how he does it so I can do the same myself if I have to.

____

The SACF/IS-WAS looks mighty cool, have been thinking 'bout trying to put together one of those. I don't have an inkjet printer handy though so the transparencies might be a bit of trouble.

For now I've just been using the Nav Map to plot my range/bearing sightings, and then drawing a line through the marks on the map to estimate target course and speed. Only problem with that is that I can't get range values until I'm within stadimeter range, which is apparently ~9000 yards.

nomad_delta

[SteamWake]

good lord thats an old call Bill, you still in New York ?

KE4JOY here

I can do around 10 to 12 wpm on a straight key but can rip off almost 40 with my paddles ;) .

I can only copy around up to 30wpm anymore. But when I was a kid I could copy 20-30 wpm while watching tv and talking on the phone :p

[Puster Bill]

good lord thats an old call Bill, you still in New York ?

KE4JOY here

I can do around 10 to 12 wpm on a straight key but can rip off almost 40 with my paddles ;) .

I can only copy around up to 30wpm anymore. But when I was a kid I could copy 20-30 wpm while watching tv and talking on the phone :p

Yeah, I'm still in NY. My novice call was KB2JII, which was an abomination to send in CW. My call isn't that old, I got it back around 1991 or so. It has such a nice rhythm to it that I've kept it.

By the way, I hadn't warmed up or anything, that was cold, so it isn't as fast as I can go.

I still use a straight key for the same reason I use a flintlock: It's more fun that way.

[Puster Bill]

Using the Watch Officer isn't cheating: It's his friggin' job to tell you bearings and distances.
Agreed, but how on earth does the WO figure out exact distance to a target that we haven't even identified yet (and which is too far away for me to have any hope of identifying...)

I guess I also don't like relying upon the WO as my only means of determining distances, 'cause he'll only tell me the range and bearing to the closest target... which means if there happens to be a life boat or something sitting closer he'll keep telling me about that instead. :p

I don't mind having the WO do his job, but I'd at least like to know how he does it so I can do the same myself if I have to.

____

The SACF/IS-WAS looks mighty cool, have been thinking 'bout trying to put together one of those. I don't have an inkjet printer handy though so the transparencies might be a bit of trouble.

For now I've just been using the Nav Map to plot my range/bearing sightings, and then drawing a line through the marks on the map to estimate target course and speed. Only problem with that is that I can't get range values until I'm within stadimeter range, which is apparently ~9000 yards.

nomad_delta

How my WO gets the range isn't my problem, as long as he gets it.;) Also, I know this is true in SHIII, not sure about SHIV, but the range the WO gives you isn't exact, it is in 100 meter increments, so there is always some 'slop' in those measurements.

If you need a rational, consider that the guy is an experienced officer, and remember that the human eye in real life can probably resolve details better than you could put on a computer screen.

If you only build the backside of the SACF, you don't need the transparencies. However, if you take the files on a memory stick or diskette to the local Staples or other office supply place, they can print them there on cardstock, transparency, or whatever, and even laminate them for you (which I recommend that you do).

Since I have a printer at home, and had cardstock already to print my QSL cards, all I had to get were some transparencies and some self-stick lamination.

I recommend that you build one as soon as you can. It makes interception and actually hitting the target much easier.

[Puster Bill]

Just to encourage others, and to keep this vaguely on topic, here are some of the submarines I've contacted over the years:


The USS Requin, SS-481:
http://img511.imageshack.us/img511/7171/picture035wq4.jpg

USS Clamagore, SS-343:
http://img266.imageshack.us/img266/6630/picture036yx4.jpg

USS Ling, SS-297:
http://img49.imageshack.us/img49/7094/picture037zj4.jpg

USS Silversides, SS-236:
http://img232.imageshack.us/img232/561/picture038tb4.jpg

USS Cobia, SS-245:
http://img45.imageshack.us/img45/8513/picture039om2.jpg

USS Batfish, SS-310:
http://img45.imageshack.us/img45/5784/picture040vp3.jpg

USS Cod, SS-224:
http://img47.imageshack.us/img47/5504/picture041sl4.jpg

USS Becuna, SS-319:
http://img527.imageshack.us/img527/8012/picture043tk3.jpg


I've also got the USS Growler, and U-505. I was disappointed in the U-505 card, though, because no where does it say that the contact was with the U-505 (that QSO was done while the boat was still outside). If you are going to do a special event, you should have QSL's that reflect that.


I've got a bunch of ship QSL's also, including the USS Yorktown CV-10 (WA4USN), USS New Jersey BB-62 (NJ2BB), USS Wisconsin BB-64 (N4WIS), USS North Carolina BB-55 (NI4BK), USS Missouri (KH6BB), USS Texas (NA5DV), USS Salem CA139 (K1USN), USS Indianapolis Memorial (W9IND), USS Kidd DD-661 (W5KID), USS Slater DE-766 (WW2DEM), USCGC Taney WHEC-37 (WB3AAL), USCGC McLane WMEC-146 (W8BXS), SS American Victory (W4AVM), CSS Acadia (VE0MMA), SS City of Milwaukee (K8GWW), LS Huron (K8HLM), and the LS Ambrose (W2AQ).

Those are just the ones I have cards for. I've contacted the USS Cavalla, and sent them a card, but never received on back. Likewise with the LST-325.

[AVGWarhawk]

http://www.usstorsk.org/radio/nk3st.htm


Contact the submarine I volunteer on. USS Torsk. Link above.

[SteamWake]

Wow thats an impressive collection !

Ive never even heard (that Im aware of) these contacts.

Some special events I gather.

Were most of these in HF ? what bands ?

[Puster Bill]

http://www.usstorsk.org/radio/nk3st.htm


Contact the submarine I volunteer on. USS Torsk. Link above.

I'd have to look back, but I swear I've contacted the Torsk before.

OK, I just checked my logbooks, and I apparently haven't. It's not that uncommon, unfortunately. Whenever there is a special event, most stations get on 20 Meters. The Torsk is a little close to me to make contact on 20, 40 Meters would be better.

My dilemma is that I am too far away from these boats to visit them in person, and when they get on the air, I'm too close to get them on 20 Meters which is where they all seem to hang out.

There are several boats I'd love to contact, including the Albacore in NH, the Lionfish in MA, the Nautilus in CT, and the Russian sub in RI, but they never seem to get on 80 or 40 Meters to give us 'local' guys a chance!

Oh, and for you SteamWake, you just missed Museum Ships on the Air. You can check http://www.nj2bb.org (http://www.nj2bb.org/) to keep an eye for the one next year. They also have a 'Submarines on the Air' event every Spring, and sometimes in the Fall. Join the "Submarine Veterans Amateur Radio Association (SVARA)" Yahoo group to find out more. I'm a member, even though I was in the Army.

By the way, if you use VOAAREA and VOACAP for propagation predictions, I have a geo file with the locations of all the museum submarines that get activated if you would like a copy.

The biggest thrill I get is when they actually use the old transmitters for these events. It's a real connection to history to work them that way.

[nomad_delta]

Just to encourage others, and to keep this vaguely on topic, here are some of the submarines I've contacted over the years

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

[SteamWake]

Just to encourage others, and to keep this vaguely on topic, here are some of the submarines I've contacted over the years

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:

[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

[Hitman]

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:

[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

[Hitman]

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:

[Uber Gruber]

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....

[John Channing]

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

[Uber Gruber]

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.

[tater]

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).

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

[XLjedi]

I guess it doesn't matter terribly much, but it pretty well eliminates the use of the stadimeter to make range estimates from far away when trying to plot a target's course and figure out an intercept.

How do you guys plot courses on very-far-away targets and determine your intercept paths? (Assuming you don't have radar, which I currently do not)

nomad_delta

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.

[John Channing]

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).

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

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

[Puster Bill]

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).

[tater]

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

http://members.spinn.net/~merrick/Stuff/range_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