Determining speed without map contacts

[Bubblehead1980]

So I have been away from SH 4 TMO for a while, just been too busy with RL to play but found sometime recently.I have played on 100 realism for a while and enjoy it but have found myself having some trouble firing torpedos accurately without map contacts.Usually I estimated speed via sound reports and visually by things such as bow wake etc and had very high number of hits/sinkings, mostly from playing enough.I am now somewhat out of practice and wont be playing enough to get back to my previous level.

So my question is, what are some methods to determine speed without map contacts turned on? with map contacts on its easy to get speed, mark a spot, wait 3 minutes, mark current location of target, then measure distance, 900 yards= 9 knots.

Tried marking positions on map without contacts but didnt work out too well, too many misses.So any suggestions on how to get speed for a "traditional" TDC shot? not looking for the trick shots some use, i prefer to do it how it was done, not finding AOB or distance difficult without contacts, just speed.Thanks in advance.

[razark]

One method I've used: http://www.subsim.com/radioroom/showthread.php?t=112765
If you've got a couple of bearing and range observations, and the time between them, it give you everything you need.

[Rockin Robbins]

Well if you aren't finding distance difficult, then speed is a done deal. You need two positions (bearing and range) plotted three minutes apart. The distance between them in hundreds of yards is the target speed.

If your speed isn't working out then you have a problem measuring distances.:D

[raymond6751]

Draw your own line.

First identify your target type. Check the ship manual for the speed indicated (normal) for the type.

Create your own line with the ruler that would be the distance it would move at that speed, in a given time.

Watch if he reaches the end of your line in the expected time. Early and he is going faster, longer and he is going slower.

It is a guess.

[Fish40]

The way I find speed is as follows: Time how long it takes the ship to cross the 0 bearing line on the scope. You will need to ID the target because you need it's length ( there is a mod out there that adds ship lengths to the RM). Once this is established, useing some basic math gets you your speed. I find this method not only pretty accurate, but a challenge since you need to correctly ID the target or your calculations will be off. Don't forget, timeing a convoy is simple since once you establish the speed for one of the ships, you have the speed of the convoy. Practice makes perfect!

[Rockin Robbins]

Yes, the time it takes the hull to cross the wire works. However, if you're taking all the trouble to be authentic, which is impossible as you give up more authenticity by turning map contacts off than you do by leaving it on, you must also be aware that this method of determining ship speed is totally inauthentic.

We have a target manual that contains every ship on the ocean. The real subs' targeting manual was a travesty. Most targets sunk during the war were grossly misidentified as to identity, tonnage, and length. Therefore, even if they used this method, which they did not, it would have yielded grossly wrong speeds.

No matter how we twist things this is a game. We roll the dice and play it the way we like because........we like it that way! Any arguments about authenticity quickly become jokes as each choice has the intended consequence, then drags along three unintended consequences, making the game even less realistic.

The map contacts on/map contacts off deal is one of those. If you're running TMO, there is only one inauthentic part of the plotting: targets which are visual only are plotted with exact position. In order to kill that you have to kill radar positions, plotting of sonar lines, airplane radar......it's a quagmire that just doesn't justify fixing one element to ruin three or four others.

If you were on a boat with radar, you would actually know the positions of the targets to greater accuracy than the game is allowed to show because of position binning (you have a choice of a dot here or here, not in between on a digital display) and the range readout on real WWII radars, which we do not have.

If you think it is more authentic to keep map updates off (or if not for that matter!) there is no way you can justify the timing of ships across the wire using their length to calculate speed. In WWII that just wasn't possible.

[Diopos]

As we're talking about authenticity, let me just remind you that the game always places our sub on the map with uber-GPS accuracy. Correctly tracking "Own" ship on the map would consist the bulk of the navigator's job. Same goes with the use of waypoints. If real life WW2 navigators had these two "options" they would feel extatic, for sure.





.

[Rockin Robbins]

That stuff can be justified because the object is to fight the boat, not take hours figuring out where you are, what the current is, doing fuel calculations (equally time consuming), etc. You're supposed to be the captain fighting your boat and that is rightly where the emphasis of the game is.

It would be more realistic to have to wash your underwear, but it can't be justified within the framework of the game.

No matter how sophisticated the capabilities of simulation become, choices will have to continue to be made about what kind of realism represents meaningless tedium (and that would be a different judgment for each and every player) and what represents legitimate game focus. And no matter what choices are made, people will be unhappy with those choices.

After all, for realistic navigation we would have to have access to the real sky (not available in SH4), a sextant, complete navigation tables for the appropriate year, and then we would have to execute all the calculations by hand, without recourse to any kind of calculator. Fun! Fun! Fun!

For some it would be fascinating. For some it would be why they quit playing. And that is only the tip of the iceberg on the realistic things that would result in the game being a total failure.

I like options myself. You should be able to configure the game to your own version of what is tedium and what is not.

[Diopos]

...not mentioning a "spherical" world.

:)


.

[sckallst]

I play with map contacts off. I get all my speeds from plotting. I do relative motion plots, rather than dynamic plots on the in-game nav map. Take a range and bearing. Plot it off to the side on the nav map, using the in-game tools, using a stationary point as Own Ship. Take another, measure distance covered. Use the nomograph to estimate relative speed. Do vector addition to take into account your motion, if any, and you will get an estimate of both a true course and a true speed. Then repeat as needed to hone solutioin. Take the readings whenever you like without worrying too much about getting them at just the right time and trying to rush through to process as is needed if you dynamically plot on the nav map.

Rather than doing this in-game you can also use the great MoBo tool that you can find like to right here at Subsim. In the Mobo materials you can find links to documents on the web that will teach you all you want to know about the subject, at least for purposes of this game.

[Fish40]

Yes, the time it takes the hull to cross the wire works. However, if you're taking all the trouble to be authentic, which is impossible as you give up more authenticity by turning map contacts off than you do by leaving it on, you must also be aware that this method of determining ship speed is totally inauthentic.

We have a target manual that contains every ship on the ocean. The real subs' targeting manual was a travesty. Most targets sunk during the war were grossly misidentified as to identity, tonnage, and length. Therefore, even if they used this method, which they did not, it would have yielded grossly wrong speeds.

No matter how we twist things this is a game. We roll the dice and play it the way we like because........we like it that way! Any arguments about authenticity quickly become jokes as each choice has the intended consequence, then drags along three unintended consequences, making the game even less realistic.

The map contacts on/map contacts off deal is one of those. If you're running TMO, there is only one inauthentic part of the plotting: targets which are visual only are plotted with exact position. In order to kill that you have to kill radar positions, plotting of sonar lines, airplane radar......it's a quagmire that just doesn't justify fixing one element to ruin three or four others.

If you were on a boat with radar, you would actually know the positions of the targets to greater accuracy than the game is allowed to show because of position binning (you have a choice of a dot here or here, not in between on a digital display) and the range readout on real WWII radars, which we do not have.

If you think it is more authentic to keep map updates off (or if not for that matter!) there is no way you can justify the timing of ships across the wire using their length to calculate speed. In WWII that just wasn't possible.




Points well taken. In your honest opinion though, what do you feel is the most "authentic" method. I understand each method comes with downsides, but if you had to pick one to mimic reality as close as possible, what would it be? At the present time I don't have radar installed.

[Rockin Robbins]

Well, the authentic method isn't anything really pushed here except in gutted's Solution Solver. It is the visual estimate of angle on the bow, because that was the authentic way to derive the target course: target bearing and angle on the bow.

Now, in practice range measurement was so pitiful you might as well forget about the result, only knowing that you could get within a factor of two. If you measured a range of 2000 yards with your stadimeter, realizing that your recognition manual might not have that actual ship in there and you are guessing here, you could say with pretty rock solid confidence that the real range was somewhere between 1000 and 4000 yards. Real useful, eh?

So speed estimates using that range/bearing couldn't be very accurate, could they? In practice, they estimated speed the same way they estimated angle on the bow. They eyeballed the bow wave to estimate. You can do the same thing in SH4. Just make yourself a scenario with a target moving at a speed and look at the bow wave. Exit, change the speed and do it again. With practice you can get pretty good!

Now, if you know the speed and course THEN you can determine the range by how many degrees he moves in a given time. See how all these seat of the pants measurements work together? And there was one thing needed to make this work: EXPERIENCE. Tons of it.

However you have to always shoot a 150% to 200% spread to get hits. That means guaranteed 50% misses. Your actual mileage will be less. Now you know why the hit ratio was so poor! Oh, you might add in a passel of defective torpedoes to the previous exercise just to keep things entertaining. And you can't use your external camera to see if the torpedo really missed the target or was defective. Merry Christmas! Now you know why they greeted radar as the savior of the submarine war! Suddenly their positions, courses and speeds were as accurate as ours in the game.

Dick O'Kane was on a cruise when his radar suffered an irrepairable breakdown. He wired back to base the equivalent of "Damn! Now I'll waste half of my torpedoes." He was being conservative.

[Platapus]

In practice, they estimated speed the same way they estimated angle on the bow. They eyeballed the bow wave to estimate.


I was under the impression that both the American and the German's were trained to use the stern wave to estimate speed.

[Rockin Robbins]

I wouldn't be a bit surprised if they were. However, the stern wave is tremendously influenced by the hull shape, and of course there is a wide variety of hull shapes. You can also judge speed by the spacing between the bow wave and the quarter wave, which is further away from the bow wave with increasing speed.

Of all the methods, however, the bow wave is the most uniform between different ships.

Now this is all about the real thing and I don't know how closely the game reflects reality in this area.

Now here's an even better method stolen from the Submarine Torpedo Fire Control Manual of 1946 (http://hnsa.org/doc/attack/index.htm). It relies only on achieving a collision course with your target. This can be done at just about any own speed, and even submerged if need be. How do you know you are on a collision course? Your target's bearing doesn't change with time. Your target is traveling from right to left. So let's say you take a target bearing of 15 degrees. Two minutes later it's 20 degrees (sorry, the alt-0186 shortcut for the degree sign doesn't work in Linux and I don't want to chase down the equivalent right now.). This means that the target is lagging behind. Either change course slightly toward the target or slow down. Take another measurement two minutes later. If you're still at 20 degrees, you have achieved a collision course. Make minute adjustments over time until you hold the same bearing for over three minutes. Collision course achieved! It's chart time:

http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/collisioncoursespeedmeasurement.jpg

All right, in official Navy terms Ab is angle on the bow. You understand that. LA is the lead angle, that's the angle between the bearing line to the target and your bow. S sub T is target speed and S sub O is Own Speed. These abbreviations are used uniformly throughout official submarine attack procedures. So, reading the formula there, Target Speed equals your own speed times the sine of the lead angle divided by the sin of the angle on the bow. The real guys would work that out in seconds on a slide rule, so you may authentically use a calculator.

Now you have with perfect authenticity calculated the speed and can derive the exact course of your adversary. Is it too much for some game players? Sure it is. Is it possible to do within the game? Absolutely. It's what I will do next time I'm caught in a boat without radar! If I can. The eyeball methods are better for quickly developing situations where you either shoot quickly or not at all. Guess this post ends up in the Sub Skipper's Bag of Tricks thread now...

And as a bonus, I found something else. You can put your target abeam and eyeball a relatively parallel course, right? You don't have to be accurate: 25 degrees off one way or another still yields pretty good results. Some idea of range is necessary too. But for what it's worth:
http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/abeamspeedmeasurement-1.jpg

OK, that means that you're on a parallel course with your target. Your courses are the same, but of course, your speeds are different. We'll just say he's a mile, 2000 yards, away. Taking a series of bearings, his bearing is decreasing, he's falling back of 2 degrees per minute and you're going 10 knots. So he's traveling two knots slower than you are! Peg that guy at 8 knots.

Now get on a collision course and do the other calc. This will confirm and give you a reliable range at the same time when you diagram it out!

[Armistead]

I thought you used the stad to get speed anyway...

[Bubblehead1980]

Thanks for the tips everyone....

I've been using to get target speed during daylight hours without contacts based on a method based used by US subs during WW II.

I have the better smoke mod so can usually see the smoke for miles like in RL.Read in many books by O Kane etc that they used high periscope to watch the smoke and keep track of them with only sporadic use of radar since they were not sure if IJN had radar warning equipment.

So I get on a parallel course and keep track via the smoke from a distance and guess the speed once i began to pull ahead, then when close in may refine estimate if needed, works pretty well during daylight and have had success.No real reliable method for getting speed at night yet but will try some of the suggested methods.

Hopefully when we have better radar come along it will help.

[Admiral8Q]

@Rockin Robbins:

Those are very interesting, yet relatively simple ways to intercept and determine speed!:hmmm: I'm going to try them out. You don't even need range for the intercept method. The speed method would need a range however in order to calculate it correctly, wouldn't it?

[Armistead]

I'll be glad when someone mods the radar range dial. I had a mod where it worked, but limited to 4 digits. Someone was working on one with 5 digits.
Even with four digits, using focus you could use the 3 minute rule by tracking it on radar. I haven't used this mod with TMO as it messes up sonar.

Like most with contacts off I time the ships crossing the wire. Realistic or not the lack of correct radar leaves no choice. Sometimes I guess by the bow wave, knowing that most ships run certain amounts.

[I'm goin' down]

I was at the local hot spot and told a couple of young ladies that I was a submariner in WW2, and had been awarded a Medal for Valor by Admirals Robberts and Stevens. I rattled off some Navy lingo I picked up in the forum. By the end of the night, they were calling me "The Commander," and asked me I could demonstrate the art of firing torpedoes. GAME? Heh! Tell that to them and I will be in lock up.

[sharkbit]

I was at the local hot spot and told a couple of young ladies that I was a submariner in WW2, and had been awarded a Medal for Valor by Admirals Robberts and Stevens. I rattled off some Navy lingo I picked up in the forum. By the end of the night, they were calling me :The Commander," and asked me I could demonstrate the art of firing torpedoes. GAME? Heh! Tell that to them and I will be in lock up.

Pics or it didn't happen!!! :p2: :D

:)