Nomad_Delta's SH4 Question & Answer Thread

[nomad_delta]

As many of you know, I've got all sorts of questions about the inner workings of Silent Hunter 4, and I'm a big fan of careful empirical testing to find out the answers to my questions. Often finding the answers to my questions only leads me to more questions, so I started writing down a list of them so I wouldn't forget to look into them later. It also helps keep me focused during my investigations and testing.

I decided it might be a good idea to post my list of questions and invite everyone else to add their own questions to the list. More importantly, I plan to keep updating this top post as new questions are added and as I find new answers to each. I'm not perfect and sometimes my logic may be flawed, so if I later find better info I'll update the answers accordingly.

Feel free to post & suggest your own questions and answers, or comment on what I have so far. Also, I won't clutter this thread up with the specific details on how I've answered each question -- but if you'd like to see my data or hear my reasoning for a particular answer, just ask. In many cases I may link to another thread where all the detailed discussion for that question/answer is taking place.

...and without further ado, it's time for:

Silent Hunter 4: Nomad Delta’s Question & Answer Thread


1. Do wind, weather, or other sea-state variables affect torpedo depth-keeping?
Answer: Yes, by about 2 feet in each direction. In 'perfect' (0 wind, no rain) weather, excluding all other torpedo depth-keeping problems, torpedos always hit and miss consistently at the same depths. In 'worst possible' (90 meters/second wind, heavy rain, heavy fog, heavy clouds) torpedos will sometimes hit when set 2 feet lower, or miss when set 2 feet higher. It's impossible to tell for sure, but it looks to me like this is actually caused by the ships themselves moving up & down in the water by that amount, as opposed to the torpedo itself actually running deeper or shallower than set.

2. Do wind, weather, or other sea-state variables affect premature torpedo detonations?
Answer: Yes, and dramatically so. In 'perfect' weather conditions, premature detonations do not seem to happen at all. In 'worst possible' weather conditions, however, I encountered a 36% premature detonation rate during testing. Interestingly, those rates do not seem to match the 'PrematureDetonation chance' values I find in the 'torpedoes_us.sim' file. According to the file, the rates should be 10% for wave-states 0-10, and 60% for wave-states 10-40. Update: As described in Answer #8, I have determined why the rates I found on this test did not match those in the torpedoes_us.sim file: I was firing at a test target only 750 yards away, and many of my torpedoes were hitting the target well before they had a chance to randomly detonate.

3. Does cargo loadout have any effect on a ship’s draft?

4. Does the depth of your sub (surface vs. periscope depth, for example) affect running depth of launched torpedoes?
Answer: Yes, but only slightly! I have found that torpedoes launched from a submerged (anywhere from periscope depth to maximum launch depth) will consistently run about 1 foot deeper than torpedoes launched from a surfaced sub.

5. Does the torpedo ‘contact/influence’ switch work in Silent Hunter IV 1.3?
Answer: No, the contact/influence switch does not work in SH IV 1.3. Torpedoes launched prior to 06/01/1943 will always be magnetic, while torpedoes launched after that date will always be contact-only. (http://www.subsim.com/radioroom/showthread.php?t=118393)

6. Did the torpedo ‘contact/influence’ switch work in Silent Hunter IV 1.0 (no patches)?
Answer: No, the contact/influence switch did not work in SH IV 1.0. The behavior is exactly the same as in SH IV 1.3.

7. Do the torpedo 'speed' values in the 'torpedo_us.sim' file have any effect on actual torpedo speeds in the game?
Answer: Yes, they do -- but there are restrictions that are not immediately obvious. After some thorough testing, I have determined that the game will accept values between 0 and 255 in knots. Setting values higher than 255 will still work, but will not cause the torpedoes to go any faster than at the 255 setting. Another important restriction I encountered is that the first speed value must be lower than the second speed value. If you set a higher speed value in the first slot, it will break the 'speed' dial in the game by permanetly sticking it on 'slow', and all torpedoes will go the first (higher) speed. The game will completely ignore the second value.
MOD: To illustrate that this does work, I've created a quick (and rather pointless) mod -- it's even JSGME-ready! Click here to download Nomad's Min & Max Speed Mk14 Torpedoes Mod.

8. Do the 'Premature_Detonation Chance' values in the 'torpedo_us.sim' file have any effect on actual premature detonation rates in the game?
Answer: Yes, it does. I tested setting the 'bad weather' premature chance to 99% instead of the stock 60%, and all of my test torpedoes detonating before reaching the end of their run. Note that premature detonation chance applies to the entire run of the torpedo, not just the distance between your sub and your target. The 'premature' detonations may take place at any random point along the torpedo's run length, including past the target if it passed underneath without impacting. So if you're having problems with premature detonations, try getting closer to your targets: it won't reduce the premature % chance, but it will make it more likely that your torpedo will hit your target before the premature detonation can occur.

9. Even though the Contact/Influence switch has been determined to be non-functional, does changing the switch setting have any effect on premature detonations by "magnetic" torpedoes?
Answer: No, it does not. In testing I actually saw a slightly higher rate of premature detonations with the switch set to Contact (11 prematures out of 23 fired) vs. having the switch set to Contact/Influence (7 prematures out of 24 fired). I suspect the difference is just a statistical anomaly due to the relatively small sample size, though, and that there is no effect to changing the exploder switch whatsoever.

10. [Question submitted by Bando] Are the explosive amount/power values for each torpedo set consistently with 'realistic and historical' values in the relevant .sim files?


11. Does the 'range indicator' on the sonar/hydrophone screen change measurement units depending on whether you have your gameplay settings on Metric or Imperial? (...and if not, what measurement units does it display in?)
Preliminary Answer: I've only tested this briefly and will need to do some more thorough checking, but it appears that the visual 'sonar ping' range indicator only displays in meters, even when you have Imperial measurements enabled. For example, I ping a target, and my sonar operator calls out the range as '3080' while the visual indicator displays just over 2800. Since 3080 yards equals 2816 meters, it looks like the visual sonar range indicator is in meters only.

12. Are the 'draft' values listed in the in-game recognition manual for Japanese merchants and warships consistently accurate within the game as of patch 1.3?

13. [Question submitted by switch.dota] Does the running depth of the torpedo have any impact on the chance to cause premature explosions?
Answer: (UPDATE) Received word from Elanaiba that they had intended for torpedo running depth to affect premature detonation chances, but that they did not have time to implement it in the code. This matches my personal testing, which did not show torpedo depth or any factors other than weather (wave state) having any effect on premature detonations.

14. [Question submitted by Tater] There is a depth setting in the DC tweak file. As I recall, the default value was something like 2500 (in 1.2). What is this value, the max depth?


15. Do torpedoes have to actually pass below a ship to trigger a magnetic detonator, or simply be within the magnetic detonation range -- even skimming the surface?
Answer: No, the torpedoes do not have to pass underneath the target to trigger the magnetic detonator. My testing shows that torpedoes with magnetic detonators will explode at the mag-det radius regardless of depth setting. As an exaggerated test, I modified the magnetic detonation radius to 50 meters and then tested firing multiple volleys of torpedoes at a large freighter at both minimum (4ft) and maximum (50ft) depths. All torpedoes exploded as soon as they reached the 50 meter mark. If the magnetic detonators required passing underneath the ship, the torpedoes set to 4ft should have reached the target and detonated by contact instead, since there was never any metal above them at any point. I recorded a brief video to demonstrate this, which you can view here:

16. What does the "depth" value for each torpedo type in the "torpedoes_us.sim" file do?
Answer: This sets the 'default' running depth for torpedos of this type. Changing the 'depth' value actually changes the starting position of the "torpedo depth" dial. The default value is 1.799999995231628 meters, which is about 5.9 feet. I've no idea why they didn't just use 1.8 meters, but that's a mystery for another day.

17. In Silent Hunter 4 patch 1.2 (and previous) there was a bug causing the green "estimated torpedo path" line from your sub to disappear from your Attack Map when you crossed the International Date Line. Is that bug still present in Silent Hunter 4 patch 1.3?
Answer: Yes, the bug is still present in the 1.3 patch. The International Date Line is at 180 degrees longitude, just West of Midway. The bug occurs when crossing the IDL, which is most common when one launches out of Pearl, and causes the green "torpedo track" indicator line to disappear from your Attack Map. I have recorded a short demonstration video of the bug taking place, which you can watch here:

18. [Question submitted by Tobus] What effect, if any, does the speed of your submarine have on the overall speed at which you can dive and surface?

[nomad_delta]

Anyone got any questions? Ask away, and I'll do my best to answer 'em "scientifically", if it's within my capabilities.

nomad_delta

[Bando]

Nomad,
I did ask in another thread, but here's my question

Is the destructive amount of each torpedo modelled in this game set realistic in the sim files?

I took a look at the torpex/TNT values of real life and compared them to the sim files. In my opinion they do not add up.

EDIT

Just read your answer in the other thread, question is still valid

[nomad_delta]

Originally Posted by Bando

Nomad,
I did ask in another thread, but here's my question

Is the destructive amount of each torpedo modelled in this game set realistic in the sim files?

I took a look at the torpex/TNT values of real life and compared them to the sim files. In my opinion they do not add up.

EDIT

Just read your answer in the other thread, question is still valid

Ok, you're on the list! (see above) Your question might be a bit difficult for me to answer on my own, since I'm certainly not an expert on what "realistic and historical" torpedo explosive amounts should be, but let's see what we can do! What source were you using to look up the 'real life' torpex/TNT values?

nomad_delta

[Bando]

At work now, I'll answer that at home.

Stand by.......

[Jungman]

7. Do the torpedo 'speed' values in the 'torpedo_us.sim' file have any effect on actual torpedo speeds in the game?


No. They are hardcoded.