Real Submarine Technology & History Q&A

[propbeanie]

Originally Posted by hunter301

This question may have already been asked but I don't have time tonight to read thru 5 pages of threads so here it is.....

From what I read in NAVPERS on the fleet type submarine the periscope was slaved to the gyro angle of the torpedo. So when they raised the periscope and gave the command "Bearing-Mark!" and lower the scope to fire how is the bearing transferred to all of the torpedoes when they switch from tube to tube to do a multiple torpedo attack?

Originally Posted by hunter301

With all this discussion of real sub life and how they work I have to ask...Has anybody seen the movie "Below"?
While I realize it's a horror flick of sorts it is IMHA one of the most visually stunning movies to date of the period date submarines. In this movie you see control aspects of what looks like a Gato or Balao class submarine that you don't usually see. Like when he jumps down into the battery compartment when the hydrogen alarms go off to check the meters. Never seen this before. Or when they go outside and swim inside the baffles of the sub to find the damage causing oil to leak onto the surface giving away their position at time.
One of the scenes that got me was the severity of damage that was being done when the German destroyer was using its grappling hooks to find the sub when it was sitting on the bottom.
Except one of the old black and white episodes of "The Silent Service" on Youtube I have never seen anything else on the use of the grappling hooks.
How often or how many ASW ships had these?
I think they would do more damage than a depth charging.
Why is this not modeled in any of the Silent Hunter games?

I am by no means, an expert, but I did stay at Holiday Inn Express last week... Gyro angle is determined by the solution of the targeting problem with the use of the TDC (Torpedo Data Computer), an electro-mechanical computer, like relay logic. That data was sent to the torpedo in the tube. It could also be put in "manually" through the computer for corrections or alterations. The inner torpedo tube door (breech) had an adjustable "stop" that would put the torpedo in the proper position so that the mechanisms to manipulate the torpedoes settings would fit in properly. (If you really want to get into the details of it all, I point you at Chapter 3 of 21-Inch Submerged Torpedo Tubes on the Maritime dot Org site, home of the Pampanito.) The skipper might say "Ready all torpedoes for firing" or "Ready tubes 1 and 2 forward. Better get number 9 & 10 ready aft, just in case." While you had the skipper & executive "targeting" with the scope, there would be at least one "team" working on the solution on paper, parallel with what the TDC would do. They might even use a "banjo" to help them figure things out. They would (usually) double-check themselves that way, time permitting, before firing.

As for the use of a hook, I know of only one documented story, and they aren't even sure about that, since the sub was submerged, and were only going by sound. I would imagine that "hooking" a sub stood a chance of damaging the hook-dragging vessel also. Trying to hook a sub, and they accidentally hook a hulk wreck, partially sunken into the bottom by sediment? Might tear part of dragging vessel off, or maybe pull their stern under, while everyone onboard gets thrown forward by the near-sudden stop... parts of the cable winch go flying as it's destroyed? One reason you won't see it in the game is because of the games engine. There is no allowance for "attached" vehicles. You can have objects "riding" on other objects, but there is no "cable" in the game...

[hunter301]

Originally Posted by propbeanie

As for the use of a hook, I know of only one documented story, and they aren't even sure about that, since the sub was submerged, and were only going by sound. I would imagine that "hooking" a sub stood a chance of damaging the hook-dragging vessel also. Trying to hook a sub, and they accidentally hook a hulk wreck, partially sunken into the bottom by sediment? Might tear part of dragging vessel off, or maybe pull their stern under, while everyone onboard gets thrown forward by the near-sudden stop... parts of the cable winch go flying as it's destroyed? One reason you won't see it in the game is because of the games engine. There is no allowance for "attached" vehicles. You can have objects "riding" on other objects, but there is no "cable" in the game...

In the movie he is looking at the ONI recognition manual when he says the ship that's attacking them has grapplers. While I'm waiting now for copies of the original ONI manuals to arrive https://www.amazon.com/gp/product/19...?ie=UTF8&psc=1
does anybody else know if they ever listed these as part of their gear?
Nothing relative just curious.

[propbeanie]

Here's an online link from that same maritime dot org site: https://maritime.org/doc/id/index.htm

[Sniper297]

I've read several historical books that mention a sub lying on the bottom hearing the sound of cables dragging across overhead, so although it wasn't done often it was done. Not trying to catch the sub like a fish and haul it out of the water, the problem was trying to locate it when it's lying doggo with motors stopped - sonar bottom echos make it real difficult to pick a confirmed contact out of all the returns coming from the bottom itself.

Speaking of sonar, we've noted in game that the IJN escorts seem to be programmed to be deaf to the sub's sonar and fathometer. In Admiral Lockwood's book SINK 'EM ALL he mentions that sub skippers were finding out as early as the summer of 1942 that a single ping was extremely unlikely to be heard by any nearby destroyers, so they frequently used single pings to confirm range to a target throughout the war.

So there's some real life fact behind it, I'm going to start pinging more often.