Real Submarine Technology & History Q&A

[ETR3(SS)]

Originally Posted by DeimosFormido

I've always wondered: what is the purpose of the horizontal steel structure protruding from subs at the aft end?

 

(that thing on the right, horizontal structure made of metal bars)

Welcome aboard Deimos! Try posting your picture again, can't seem to see it.

[Aktungbby]

DeimosFormido!

[Moonlight]

Originally Posted by ETR3(SS)

Welcome aboard Deimos! Try posting your picture again, can't seem to see it.

I'm not surprised it was enormous, this is the picture scaled down.... a lot.

[ColonelSandersLite]

I'm guessing you mean the propeller guards? The purpose is to protect the propellers.

Been a long while since I looked into them, but my understanding is that they where welded to some boats, bolt on on other boats for removal at sea, and some boats where never even outfitted with them.

[Aktungbby]

Indeed! some had some did not The USS Gato herself never had them. In researching this topic, I came across this interesting vessel...slightly updated. Everything that could go wrong did. USS Grunion Although there is no absolute certainty the evidence strongly suggests that the Grunion was lost as a result of horrific torpedo performance in the confrontation with the Kano Maru. One torpedo ran low, but despite the magnetic pistol it did not explode; two others bounced off the Kano Maru without exploding. The last one circled back, hitting the periscope supports on the submerged submarine without exploding.That event, coupled with a jammed rear dive plane, triggered a sequence of events that led to loss of depth control. At about 1000 feet the sub would have imploded, then hit the bottom, breaking off about 50 feet of the bow. It then slid 2/3-mile down the side of an extinct volcano, finally coming to rest on a notch on the underwater mountain. https://en.wikipedia.org/wiki/USS_Grunion_(SS-216)

[ColonelSandersLite]

Also worth mentioning. If you look at pictures of the prop guards, it's very obvious that there are a lot of variations of them.

Compare:


Notice that the guard rails are very flat. 2 pairs of cross braces. The lower set is almost horizontal and the top set is heavily angled down. I believe the vertical bar there is a temporary construction support, but I'm not 100% sure on that.




Here's a couple of photos from the wreckage of the grunion:



Notice that the cross braces on the topside are nearly horizontal and the bottom braces are angled sharply, the opposite of the above. Also notice that the forward side is angled more than the stern side. Again, the opposite of permit.



Silversides:

Just completely different, I believe that this is the bolt on setup as evidenced by the next photo.

Silversides without guards:


Silversides Today:

Notice the configuration changed sometime after the above picture was taken. I don't know when.


Barb:

No guards at all.

Cod today:

Again, completely different.

[TorpX]

Apparently, the Clemson-class DD's had them also.

I couldn't find a good picture of one, but Roscoe's Destroyer Operations book has a drawing of early war Clemsons with them.

[ColonelSandersLite]

Never knew that, but since you bring it up: You can see them clearly on the stern in this photo.



Edit:
And here's one with a different POV (different ship)

[ShotMagnet]

Elsewhere in this thread it's mentioned that heavy seas can be felt even as deep as 100 feet. My question: since torpedoes of the period commonly ran only a dozen or twenty feet below the surface, how true could they be expected to run in heavy seas?

Could they be launched from much deeper, then assume pre-set depth during their run and therefore mitigate how heavy seas might affect them?


Shot

[Sailor Steve]

They couldn't. Heavy seas were the bane of submarines in WW1 and WW2. Torpedoes could "broach", or break the surface and then dive deep and lose control, or they could break the surface and then explode on hitting the water again. Both Germans and Americans had problems early in the war with torpedoes running too deep on the best of day. Heavy seas made it worse.

According to Peter Pad field's War Beneath The Sea or The Battle of the Atlantic, by Terry Hughes and John Costello (It might be either one - it's been a long time since I read them, and neither's index is helpful in this matter), sometimes in really bad weather an entire convoy would heave to and maintain position, all pointed into the seaway, knowing that no U-boat could attack in those conditions.

As to your second question, also no. The inner torpedo loading door opens inward, and with the outer doors open the pressure at anything deeper than periscope depth could force the inner door open. On top of that, firing on a sonar bearing only was tried by the Americans early in the war and found to be much more difficult than anticipated. So difficult, in fact, that it never worked in actual practice. You would have to take a periscope sighting, and by the time you reached 100 feet or so the solution would be so old you would have pretty much no chance of hitting your target.

So submariners didn't like foul weather any more than the surface sailors did. The only difference was that the sub guys could ride out the storm in relative comfort.

[ShotMagnet]

Thanls, SS. Biding my time and watching YT vids of people playing SH 4 while I await my own copy of the game, I've noticed that a lot of people battle-surface on wounded targets and often elect to administer the coup de grace with the deck gun.

Was this a common practice? I wouldn't think so, but -shock though this will come to some of you- I don't know everything.


Shot

[Sniper297]

According to a lot of the historical books I've read (try your local library non fiction section, maybe you can learn everything) it was pretty common, not only to finish off damaged ships but to sink small ones that weren't worth a torpedo. Sometimes it backfired, I recently read an account of a gun attack on a sampan which turned out to have more and heavier weapons than the sub.

As for the torpedoes, I was in a heavy helicopter anti-submarine squadron, and we had 3 incidents on the same exercise of a Mark 46 torpedo running up the backside of a wave and flying into the air. I didn't personally see these, but the pilots claimed they flew up right through the rotor arc without hitting any of the blades.

[Vox165]

*Bump.* Stumbled on this great thread, for noobs like me looking for RL fleet boat info.

[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?

[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?