Real Submarine Technology & History Q&A

[TorpX]

I often play the S-class boats, and I was wondering about their engine speed options.

We know what we can choose with fleetboat, which have four engines:

1/3 ------------------- one engine
Slow ----------------- two engines
Standard------------- three engines
Full ------------------ four engines
Flank ---------------- four engines + battery

So what would we have with a two engined S-boat? Would most of the engine telegraph orders be meaningless?

[Admiral Halsey]

Originally Posted by TorpX

I often play the S-class boats, and I was wondering about their engine speed options.

We know what we can choose with fleetboat, which have four engines:

1/3 ------------------- one engine
Slow ----------------- two engines
Standard------------- three engines
Full ------------------ four engines
Flank ---------------- four engines + battery

So what would we have with a two engined S-boat? Would most of the engine telegraph orders be meaningless?

I think in the case of the S-Boats the engine RMPs would be lowered.

[Snarf]

http://www.navsea.navy.mil/nswc/card...s/bayview.aspx
I'm surprised nobody has made mention of this. After pearl harbor the navy wanted an inland naval facility. This resulted in a naval base at Lake Pend Orielle in Idaho.

[merc4ulfate]

Read em and weep or laugh.

Digital format of the microfilmed patrol reports of the U.S. Fleet boat during World War II beginning in 1923 until the end of the war.

http://www.hnsa.org/doc/subreports.htm

I enjoy reading it straight from the horses mouth.

================================

[scott613]

Hi Folks,

I loaded up the "improved ship physics" mod with the recommended RFB - and while I think it improved the turn rates - does it make the dive happen too fast ? Either crash dive or normal dive seems to happen in well under 30 seconds - that seems a bit too quick to be realistic ? Anyone know what average dive times were on WWII submarines - both crash and normal ?

[Dread Knot]

For a Gato or Tench class boat, 40 to 45 seconds was the norm. Eventually improved crew training and cutting the conning tower with limber holes to enable free-flooding cut this time down to 30-35 seconds.

[scott613]

Thanks for the info - modern boats couldn't even come close to matching those dive times - but - I guess they really don't need to anymore.

[Dread Knot]

Given their massive size that would be difficult for modern boats. But it sounds like submerging is something you really only do once a patrol nowadays.

[Sailor Steve]

Originally Posted by scott613

Either crash dive or normal dive seems to happen in well under 30 seconds?

A "normal" dive involves carefully flooding the ballast tanks to neutral bouyancy and using the planes to control the dive. A crash dive means flooding everything and putting the planes on full down. This is why a crash dive takes the boat so deep - it takes time to blow the tanks to neutral and pull out of a dive like that. A "normal" dive should take a lot longer to get under than a crash dive, possibly twice as long. I'm betting nobody ever timed a normal dive, because nobody cares how long that takes.

[TorpX]

Originally Posted by scott613

Hi Folks,

I loaded up the "improved ship physics" mod with the recommended RFB - and while I think it improved the turn rates - does it make the dive happen too fast ? Either crash dive or normal dive seems to happen in well under 30 seconds - that seems a bit too quick to be realistic ? Anyone know what average dive times were on WWII submarines - both crash and normal ?

I'm working on the next version of ISP, and may tweak sub diving some. I'm not entirely happy with them either.

Part of the problem is that details of the dives is lacking, and they don't say if they if it took X seconds to reach periscope depth (and level off), or if it took X seconds to reach periscope depth (on their way to 200 ft.). I made the assumption that the times listed were the former, as I don't see crash diving to 200 ft. as a practical course of action, in general.

Since this is a war simulation, I assumed that even 'normal' dives were made on a hasty basis, and started from a condition of 'riding the vents' (where possible), having holes drilled in the superstructure, alert crew, etc.

The game only has 'crash' and 'normal' dives, with no manual control of planes/tanks, or other controls. So options here are limited. If I based 'normal' dive characteristics on peacetime performance, this would likely be a severe handicap for players.

[Joalphski]

A "normal" dive involves carefully flooding the ballast tanks to neutral bouyancy and using the planes to control the dive. A crash dive means flooding everything and putting the planes on full down. This is why a crash dive takes the boat so deep - it takes time to blow the tanks to neutral and pull out of a dive like that. A "normal" dive should take a lot longer to get under than a crash dive, possibly twice as long. I'm betting nobody ever timed a normal dive, because nobody cares how long that takes.

No wonder why my sub keeps diving after I try to crash dive then immediately try to go to periscope depth. Thx for info. My wonder has been answered.

[nionios]

I would like to ask if the submariners used to rescue the survivors of the ships they had just sunk, in real war of course.Maybe they were obliged to do so?
Also during bad weather or when on high seas do the lookout crew remained on the bridge or the sub remained on surface with only periscope for lookout?

[Aktungbby]

Since you ask in SHIV thread I'll restrict it to the Pacific war: from a previous post:
In May 1942 the Japanese began transferring POWs by sea. Similar to treatment on the Bataan Death March, prisoners were often crammed into cargo holds with little air, food or water for journeys that would last weeks. Many died due to asphyxia, starvation or dysentery. Some POWs became delirious and unresponsive in their environment of heat, humidity and lack of oxygen, food, and water. These unmarked prisoner transports were targeted as enemy ships by Allied submarines and aircraft.
More than 20,000 Allied POWs died at sea when the transport ships carrying them were attacked by Allied submarines and aircraft. Although Allied headquarters often knew of the presence of POWs through radio interception and code breaking, the ships were sunk because interdiction of critical strategic materials was more important than the deaths of prisoners-of-war Lisbon Maru was carrying 2,000 British POWs from Hong Kong to Japan in appalling conditions when torpedoed by USS Grouper on 1 October 1942. 800 POWs died when the ship sank the following day. Many were shot or otherwise killed by the ship's Japanese guards.
Rakuyo Maru

Rakuyo Maru was torpedoed 12 September 1944 by USS Sealion which later realized the ship carried Allied POWs. Footage of some of the survivors subsequently being picked up by the submarine is available
Suez Maru Maru was a 4,645-ton freighter with passenger accom­modation. She sailed on 25 November 1943 with 548 POW (415 British and 133 Dutch) from Ambon bound for Surabaya. The POWs were all sick men from the work-camps on the Moluccas and Ambon. Twenty were stretcher cases. On 29 November 1943 the ship was torpedoed by USS Bonefish near Kangean Island east of Madoera Island. Most of the POWs drowned in the holds of the ship. Those who escaped from the holds and left the ship were shot by the Japanese. There were no survivors.
Shinyo Maru
Shinyo Maru was attacked by the submarine USS Paddle on 7 September 1944. Two torpedo hits sank the ship and killed several hundred US, Dutch and Filipino servicemen. Japanese guarding the prisoners opened fire on them while they were trying to abandon ship or swim to the nearby island of Mindanao. 47 Japanese and 687 Allied POWs were killed. [4][5]
Junyō Maru
The 5,065-ton tramp steamer Junyo Maru sailed from Batavia (Tandjoeng Priok) on 16 September 1944 with about 4,200 romusha slave labourers and 2,300 POWs aboard. These Dutch POWs included 1,600 from the 10th Battalion camp and 700 from the Kampong Makassar camp. This 23rd transport of POWs from Java was called Java Party 23. Java Party 23 included about 6,500 men bound for Padang on the west coast of Sumatra to work on the Sumatra railway (Mid-Sumatra).
On 18 September 1944 the ship was 15 miles off the west coast of Sumatra near Benkoelen when HMS Tradewind hit her with two torpedoes, one in the bow and one in the stern. About 4,000 romushas and 1,626 POWs died when the ship sank in 20 minutes. About 200 romushas and 674 POWs were rescued by Japanese ships and taken to the Prison in Padang, where eight prisoners died. In reality, no skipper of a US submarine could handle the number of POW involved in the above examples of Maru sinkings; and to do so would have endangered the sub crews just from the contagion: typhus and dengue alone, borne by the POWs. In the worst sense, a military decision regarding the 'expendability' of these men was made, and the decision to knowingly sink the vessels was still made. When a ship is sinking, the last man out ahead of the rising water closes the hatch...on those unfortunates still on the ladder; SOP. The ship comes first...always. AND additionally from 2014's nominated Post of the Year; IMHO http://www.subsim.com/radioroom/showpost.php?p=2171794&postcount=8 :"Let's say in real life in 1942, the ship sinks slowly and there are several hundred Japanese survivors in boats or in the water. Even if you are the most humane of skippers, where would you put them"...

[Threadfin]

No, there was no obligation to rescue survivors, particularly enemy survivors, though some would be hauled aboard as prisoners. However, there were many instances of US boats rescuing allied survivors. For example in July of '43 Permit battle surfaced and sank a Russian trawler with the deck gun and rescued the crew. In January of '44 Guardfish sank the US salvage ship Extractor and rescued the crew of 70. Incidently this was the only confirmed sinking of a US surface ship by US subs.

In maybe the most dramatic example, in September of '44 a wolfpack consisting of Growler, Sealion and Pampanito, was ordered to attack a convoy of 6 ships carrying about 2000 POWS ships near Luzon Strait. Growler attacked first, sinking the frigate Hirado and the destroyer Shikinami. Sealion attacked next, sinking the huge 9,400 ton transport, Raykuyo Maru, and the 8,400 ton transport Nankai Maru. He also hit a tanker in this attack.

The Japanese rescued most of the Japanese in the water, but left the POWs to their fate. The next day Pampanito returned to the area of the attack and began to find survivors, who were shouting 'pick us up please' in English. As a typhoon closed in two more boats, Barb and Queenfish were ordered to join in the rescue.

Enroute to the scene, Barb encountered the carrier Unyo and sank her.

Of the 1,318 prisoners on Rakuyo Maru attacked by Sealion, 159 were rescued by the US boats. Japanese trawlers and frigates rescued 136 men for a total of 295. Of the 900 men on the Kachidoki Maru sunk by Pampanito, 656 men were rescued by a Japanese whale ship, Kibibi Maru.

Then the typhoon prevented further searching and the boats broke off and left the area.

[nionios]

Thank you both for the full response.