Recon Mission Hiroshima Harbour (!?!?)

[Michel78]

Gents,

A while ago I found the SH4 disc at my attic and started playing. :yeah:

Doing a career right now and reached July '44 and have just gotten the mission to do a photo recon of Hiroshima harbour...and looking at the map I wonder how this is done.

This city lays far away from the high sea and the map shows largely shallow water.

Am I supposed to race on the surface towards this city during the night?

Or hop from one deep spot to the other and hide there during the day?

Your advice is needed, thanks in advance.

Greetings,
Michel

:salute:

[Torplexed]

My advice would be don't bother.

My guess is you are playing with the stock game. Going to reconnoiter the anchorage at Hiroshima is in no way a historically realistic mission. US submarines weren't routinely sent to take pictures of heavily defended naval bases in mined, shallow waters crowded with fishing boats and picket vessels using bad charts. It's not the type of mission any US submarine was ever assigned during the war. Poor or lazy research for the stock game is what it really is.

It probably can be done. The stock game does a lousy job of simulating the dangers of operating in such conditions. But it just seems gamey to me.

Oh, and congrats on your first post! :salute:

[captcrane]

Ahoy Michel ! Hey I know its just a game I play the stock version of Sh4 too. The Hiroshima recon is really tough. I had that mission. Pretty sure it took me 2 days game time to complete probably twice that in real time. I had to study the map and pick a good spot about half way to the harbor and stayed hidden then surfaced at nightfall to complete it. There are many hidden dangers along the way. IE land fortifications that fire at you not to mention the amount of traffic. Stealth is the big thing. My own thoughts anyway. It might not be historically accurate but hell it was a blast. Came away with like 70 some % damage but I remember it well. It's a game have fun!

[Crannogman]

There was a post a little bit ago about modifying the sub file to make your boat run "decks awash." With your keel at about 27 feet, most of your boat's hull (except the fo'c'sle) will be below water, making you much more difficult to spot. You can't go any faster than when you're fully submerged, but you can use diesels and radar, plus you can dive a lot more quickly than from fully surfaced. It's fantastic for night attacks and for moving during daylight under Jap aircover, and likely would help you get through the harbor.

That said, the recon mission is probably a waste of your time. If you can't stand the idea of going home without completing a mission, and the game won't give you another, try spotting a convoy and reporting the contact. If you have torpedoes, usually COMSUBPAC will order you to attack, and you'll get an objective you can accomplish by sinking a couple ships.

[TorpX]

Your advice is needed, thanks in advance.


Welcome aboard! :salute:

+1 vote for ignoring the mission.

Don't get me wrong, I'm all for following orders, provided they make sense. That one doesn't. You run into these things from time to time.

[aanker]

Welcome aboard! :salute:

+1 vote for ignoring the mission.

Don't get me wrong, I'm all for following orders, provided they make sense. That one doesn't. You run into these things from time to time.

make that +2 votes for ignoring that objective.

If you want to do it just for fun, don't get spotted. You may need to puddle jump to submerge (hide) at 55' for a day - it is an exciting mission but completely unrealistic.

Happy Hunting!

[SSI01]

A question for the forum re: running with decks awash: doesn't this in some ways increase your visibility to enemy air and surface units? I would think so due to the increase in splash caused by having the conning tower closer to the water, plus water surging through the deck grates. I recall seeing this done for real in a quick clip from "Run Silent, Run Deep" when Burt the XO tells the control room to flood down to 26 feet to put the boat's decks awash for that bow-on shot against the Japanese DD. What was shown on the following film clip sure looked like a lot of splash to me. BTW that bit about being able to dive faster with decks awash was clarified by a statement made by Burt to that effect.

[Sailor Steve]

A question for the forum re: running with decks awash: doesn't this in some ways increase your visibility to enemy air and surface units?
Probably not. Don't forget that in a movie like that the "dialogue" shots don't necessarily coincide with the external shots, which in many cases may be stock footage. Also remember that while the book was written by a retired sub skipper the movie actually deviates quite a bit from what was written in the book.

The moral is never trust a movie for anything historical. They sometimes get it right, but just as often not.

Here is a good discussion on 'decks awash'.
http://www.subsim.com/radioroom/showthread.php?t=200718

[TorpX]

A question for the forum re: running with decks awash: doesn't this in some ways increase your visibility to enemy air and surface units?
Maybe the AI sensors can 'see' the splash, but I don't think we can assume this to be so. The game mechanics tend to be kind of sloppy in these matters.

The best case that I've come across for the 'decks awash' tactic was where it was used by a USN sub to reduce their RADAR profile. That is, the author specifically cited that reason for going decks awash. Unfortunately, nothing was said about how deep, how fast, etc., etc.

In general, I've read that the fleetboats, with the gray paint scheme were very difficult to see on a dark night (even without being 'deck awash').

[SSI01]

Yes indeed; the Luftwaffe, after much experimentation, settled on a color scheme of a basic medium grey with a dark grey mottled overspray for their night fighters that was indeed very difficult to pick out on a dark night with little or no moon.

I've seen photos and illustrations (i.e., Squadron/Signal pubs "U.S. Fleet Boats in Action") depicting a US fleet boat with the upper three or four feet of its attack scope painted pink. I can't remember if it had a mottled pattern sprayed over it.

[SSI01]

There is one other thing related to a fleet submarine's height above water/hull in the water, and that is the turbo blow. I read about it being used by Capt Enright in Archerfish when she was pursuing Shinano prior to sinking the ship. IIRC Shinano was making around 19 or 20 knots which was effortless for that ship but a real strain for Archerfish. I recall reading that Enright used the turbo blow feature (venting exhaust gas from the diesels into the ballast tanks?) to try to raise the boat's hull out of the water by a few inches. He was desperate for any advantage that would let the boat go just that much faster to keep pace with Shinano.

It would seem this might make the boat marginally more unstable by pushing just a little more mass out of the water; if you're trying it in any kind of a sea it smacks of desperation.

BTW Lockwood didn't seem to have any problems with anything Enright was doing to further the pursuit, and may have guessed he was using this method. After Archerfish sent her contact report to COMSUBPAC, described conditions and asked for help from any boats in the area, it's obvious they pried the admiral away from his desk. Only Lockwood would have composed a reply that ended with "KEEP AFTER HIM JOE YOUR PICTURE'S ON THE PIANO."

[Michel78]

Well, I went in and got out. Yes, it's cheesy subsim wise but I'm Dutch and had a blast.

It cost me the weekend and was worth it.

Moved from the high seas into the straight between Kyushu and Shikoku islands at the end of the afternoon. Surfaced at nightfall and went full speed ahead towards Hiroshima harbour.

Arrived there at nights end but was too short on time to make the photo before sunrise. I decided to retreat to a underwater trench just before the Hiroshima anchorage area. That spot was 110 meters deep, the thermal layer started at 78m.

Stayed there for the day until sunset. Went to decks awash, into the anchorage, to periscope depth again, got close enough and took the damned picture.

Did I already mention that the Shokaku was anchored there? 'We' put four mark 23's in her which caused sinking.

All this slow manoeuvring (3 knots at most) took 2/3 of night time so I decided to go back to the same trench. And spent again the entire daytime at the bottom. Only one convoy passed.

At nightfall we got up en went full speed ahead towards the high seas. Unfortunately we got spotted by a coastal battery and took 16% hull damage before we got out.

It was a nice experience but being so deep inside Japanese waters was just BS.

[Aktungbby]

Michel78!:salute:

[Sniper297]

U-boats used diesel exhaust to completely empty the saddle tanks after surfacing, US subs used a low pressure turbo blower. The idea in both cases was to conserve the high pressure air. The theory behind the constant running of the blowers/exhaust was to create a constant stream of air bubbles along the hull which would reduce drag. Which of course works, but the effect is not worth the effort, it might increase max speed from 21 knots to 21.000000000000000000000000000000000000001 knots, hardly practical.

The theory about the instability is completely ridiculous, any submarine is designed to sink then kept afloat by ballast tanks, the pressure hull is mostly submerged even in full surface trim. Partial flooding of the ballast tanks to decks awash puts the entire hull underwater, lowering the center of gravity. The idiot who wrote the article was applying surface ship physics and using a theoretical model with flooded tanks above the water, ballast tanks are mostly submerged even when completely empty plus the sub is bottom heavy to begin with.

Here's the tutorial;

http://www.subsim.com/radioroom/showthread.php?t=211613

My tests showed that in game the sub is less visible in that trim, either from surface ships or aircraft, and can get much closer without being spotted. The game does not take spray and bow waves into account for visibility, so speed is not a factor, you can be kicking up bright white spray in the moonlight at 12 knots or creeping along at 2 and there's no difference. Another unrealistic effect is on sonar - in real life the diesels would be audible to a destroyer's hydrophone a long way off, but the game doesn't use enemy sonar until the sub is submerged and running on the electric motors. Also ridiculous but that's the way it's programmed.

That said, it's possible to sneak into harbors for the photo missions, but not really critical - renown for completing missions varies from 100 points to 500 points. In real life completing the mission would be a high priority, in game you can actually ignore the mission on every patrol and still get medals for sinking enough tonnage. That's stock game, I'm sure there's a mod someplace that either increases renown for mission accomplished and reduces renown for sinking tonnage.

[Sailor Steve]

The idiot who wrote the article was applying surface ship physics and using a theoretical model with flooded tanks above the water
You may well be right, but that "idiot" was also a WW2 submarine vet.
http://www.subvetpaul.com/

That in itself means nothing, because a lot of men who served in a lot of capacities didn't know anything beyond their own specialties. That said, calling someone an idiot is more than a little demeaning.

That said, it's possible to sneak into harbors for the photo missions, but not really critical - renown for completing missions varies from 100 points to 500 points. In real life completing the mission would be a high priority.
In real life no submarine was ever given that mission. As I've pointed out elsewhere, there were only fourteen photo recon missions ever assigned, and every last one of them involved taking pictures of island defenses prior to invasion.
https://books.google.com/books?id=5lTI_dF4jocC&pg=PA283&lpg=PA283&dq=us+submarine+photo+recon+ww2&source=bl&ots=z8PRfm2DSj&sig=2djIPm3SdXVrL2LANIiUpAuc-fU&hl=en&sa=X&ei=NORtVeK4C8uQsAWB-oKQDA&ved=0CB4Q6AEwAA#v=onepage&q=us%20submarine%20photo%20recon%20ww2&f=false

[Sniper297]

No argument here, in real life there were nets and anti submarine mines (set at 60 feet or so, to allow surface ships to pass over but would kill a sub at periscope depth) guarding all the entrances to the inland sea, in addition to regular air and surface patrols. The water was so shallow over most of the inland sea that the only thing more ridiculous would be a U-Boat sent to take pictures in the Everglades.

[Hambone307]

You could just wait until '45 and the Enola Gay will take care of Hiroshima for you! :yeah:

[merc4ulfate]

I have ran it before. Surface during the day and hit the deep points to hide in.

It can be done.