Convoy Attack Technique

[Joefour]

Hi Guys,

I am submitting this post for criticism, constructive or otherwise.
I have done this a few times and figured it was time to get other peoples' input. I haven't seen this method in the manuals, nor in any of the past threads, so if someone has done this before please quote chapter and verse so I can go have a look at it.
This is the method I have developed for a convoy attack:
One caveat:I would NOT attempt this if the convoy has any flanking escorts on the side of the convoy closest to you. You can try it but you are really rolling the dice.
Second caveat: Don't use this method if the convoy's speed is faster than what you can do at flank speed while submerged.

First:Get as close as possible without being detected, either at periscope depth or with decks awash. That's a no-brainer, of course. Pick out a target, or targets as the situation allows. Then pick out what I call a "cover ship", preferably a big fat noisy cargo ship inside the convoy and IN FRONT OF your target(s). Just make sure your cover ship isn't carrying racks in back, if you get my drift. This might be a little difficult if you are attacking at night. especially if there is no moon. Fire off your torpedos at your targets and immediately head for your cover ship at flank speed, diving as quickly as possible to 25-30M. Just make sure you will be below the cover's draft with some room for safety.
Now this is where it gets a little tricky. Just as your about fire and then dive, mark the position and course of your cover ship. It will make it a bit easier with the hydrophone readout. The goal is to get directly underneath or just behind your "cover", keeping the hydrophone "tail" as short as possible. If you can hear the racket of the propeller and engine loud and clear just above your head you know you are in a good position. Your own noise is masked by the ship above you. Now using the hydrophone graphic, match course for course and knot for knot with the cover ship above you. This might be a bit difficult since once your torpedos have found their mark, everyone will be zigzagging like crazy. That's why it's better to use a ship inside the convoy rather than one of the outer ones.
The escorts will be running around with searchlights and lighting off star shells, looking everywhere except where you're at. Keep this up, until things calm back down, the zigzagging stops, and the escorts' positions look like they are back to guarding the flock rather than looking around out in left field for a sub that ain't there.
When you feel it's safe, rig for silent running and slink away. Surface at a safe distance and flank ahead of the convoy and repeat the dirty business as desired.

Does this sound legit? If not, feel free to dump on me. I have tried this with both SH3 stock and GWX, with good results. It sure beats hell out of getting D/C'd for hours.

It was kind of eerie. A couple of nights after I decided to write this post, I flipped on a Netflix Instant comedy with Kelsey Grammer called "Down Periscope". I thought it was going to be another loser, but actually enjoyed it, in spite of the usual gags like farting in a crowded submarine while at depth. Anyways, there is one scene where he is involved in a war game (rigged against him) and he and his crew infiltrate Norfolk, VA harbor following just behind a super tanker, using its propeller cavitations to mask their own noise from the other guys. Sent some chills up my back.

[Cybermat47]

Sounds like a good tactic. I might see if it'll work in SH5... or if I'm skilled enough to pull it off.

[Joefour]

I had tried swimming with the convoy at periscope depth to stay out of the way of asdic, keeping my scope down and using the hydrophone only, but when they started crapping bricks and zigzagging all over the place, I was getting the hell beat out of my Turm when they bumped into me. So this ocurred to me one day, and it worked. The other thing is that the escorts are not fond of dumping D/Cs in the middle of the group; they'd be defeating their purpose and sinking their own freighters way too often.

I must admit that it's a lot easier in stock SH3 because the escorts "tails" are painted red. It's a lot easier to keep track of them.

[GJO]

Hiding in the convoy works fine in the early years of the game but once the merchants are armed and the escorts become more determined (from 1943 on) it is likely to prove fatal because the hunters will find and destroy you at all costs!

[Pisces]

I'm not sure if the prop-noise of the "cover ship" hides your own. (In reality it would probably) I fear the SH3 stealth model isn't so sophisticated. Any escorts are probably staying away because they don't want to collide with the "cover ship". Their ASDIC and hydrophone should still pick you up.

Also, going for halve an hour or more at flank-speed submerged is a pretty heavy drain on your batteries. Going deep and then slow seems more economical. With better protection/advanced warning against a stray depthcharge. But maybe not later in the war.

[Paulebaer1979]

I'm not sure if the prop-noise of the "cover ship" hides your own. (In reality it would probably) I fear the SH3 stealth model isn't so sophisticated. Any escorts are probably staying away because they don't want to collide with the "cover ship". Their ASDIC and hydrophone should still pick you up.

Yes. Normaly engines of cargo ships are much louder than engines of subs (even at flank). But i´m not sure, if this is coded in SH3.

Also, going for halve an hour or more at flank-speed submerged is a pretty heavy drain on your batteries. Going deep and then slow seems more economical. With better protection/advanced warning against a stray depthcharge. But maybe not later in the war.

Yes. Deep and slow is better.

Hiding under a cover ship makes sense, if you know the draft of the other ships around you, so you can launch your torps submerged. But that needs a lot of paperwork by hand for plotting courses and postions.

[banryu79]

Intresting technique, I will surely try it the next time I get a convoy under my hands (still in 1939, early war, second patrol).

I also think about a little variant of your technique: after you hide under the baffles and match course/speed with your cover ship, instead of navigating in this way for the next half and hour or so, slowly and steadly increse depth till near maximum depth while slowly decrese speed till silent running, eventualy going for all stop while listentning on hydrophone and waiting for the whole mess to go away... :hmmm:

[maillemaker]

I have used enemy ships as cover many times but I'm pretty sure the escorts always knew I was there. They just keep their distance to avoid hitting the merchant. This works really well with a Type XXI when you can slalom around and under ships of the convoy as you pick and choose targets. At 15+ knots the escorts can't keep up with you in the pack.

In fact, I have parked in shallow water next to a sunk-and-bottomed ship before and let the destroyer circle me - they won't drive in for fear of hitting the wreck. I then shoot at them as they cross my bow or stern tubes. Sometimes it even worked. :)

Steve

[Paulebaer1979]

In fact, I have parked in shallow water next to a sunk-and-bottomed ship before and let the destroyer circle me - they won't drive in for fear of hitting the wreck. I then shoot at them as they cross my bow or stern tubes. Sometimes it even worked. :)

Nice idea. But i always hunt in deep waters - so i´m not able to try this.

[banryu79]

In fact, I have parked in shallow water next to a sunk-and-bottomed ship before and let the destroyer circle me - they won't drive in for fear of hitting the wreck. I then shoot at them as they cross my bow or stern tubes. Sometimes it even worked. :)

I'm no expert but shouldn't the destroyer try to take you out by gun fire, if he knows were you are and you are shallow? (in RL, I mean)

[Joefour]

Hiding in the convoy works fine in the early years of the game but once the merchants are armed and the escorts become more determined (from 1943 on) it is likely to prove fatal because the hunters will find and destroy you at all costs!

How many of the armed merchants would be equipped with hydrophones?
I do this with the hydrophone only, with periscope DOWN. And, to be honest, I'm still operating in 1941. Haven't gotten to '43 yet.

[Joefour]

Intresting technique, I will surely try it the next time I get a convoy under my hands (still in 1939, early war, second patrol).

I also think about a little variant of your technique: after you hide under the baffles and match course/speed with your cover ship, instead of navigating in this way for the next half and hour or so, slowly and steadly increse depth till near maximum depth while slowly decrese speed till silent running, eventualy going for all stop while listentning on hydrophone and waiting for the whole mess to go away... :hmmm:
That might work too. But my main object after the attack is to wait until the escorts stop looking for me. If you were to slowly sink down lower and wait, there is the possibility of them picking you up with a ping and echo.

[Joefour]

I'm not sure if the prop-noise of the "cover ship" hides your own. (In reality it would probably) I fear the SH3 stealth model isn't so sophisticated. Any escorts are probably staying away because they don't want to collide with the "cover ship". Their ASDIC and hydrophone should still pick you up.

Also, going for halve an hour or more at flank-speed submerged is a pretty heavy drain on your batteries. Going deep and then slow seems more economical. With better protection/advanced warning against a stray depthcharge. But maybe not later in the war.

That's why I don't even get near the convoy unless my batteries are 100% charged up. Something I should have done but didn't was to time how long it takes for the convoy to settle back down into it's routine. I do remember the meter getting pretty low. I have noticed that in almost all of the convoys there seems to be one escort that is persistant for awhile after the others have given up and moved on. But in that case it's a lot slimmer chance of one escort finding you than if 3 or 4 are hunting you.

[maillemaker]

I'm no expert but shouldn't the destroyer try to take you out by gun fire, if he knows were you are and you are shallow? (in RL, I mean)

Yes, it is a totally unrealistic situation. Presumably they would just run past the wreck and depth charge the crap out of it. Or ram me.

Steve

[banryu79]

I have noticed that in almost all of the convoys there seems to be one escort that is persistant for awhile after the others have given up and moved on. But in that case it's a lot slimmer chance of one escort finding you than if 3 or 4 are hunting you.
Yes. I think that (again, in RL) the tactical objective of that lone escort was to force the uboote to stay down, while the rest of the convoy fly away :hmmm:

[Aras]

Hiding under a cover ship makes sense, if you know the draft of the other ships around you, so you can launch your torps submerged. But that needs a lot of paperwork by hand for plotting courses and postions.

@Joefour - Interesting tactic. I will try defiantly try it. Combined with what Paulebaer mentioned, it may give you the opportunity to sink more targets.

[Paulebaer1979]

@aras: if you want to try it, check the settings in the NSS_Uboat**.cfg (inside SH3/data/Submarine/NSS_Uboat**/) first.
TorpLaunchMaxDepth=25;metersThis should work most times. I don´t know from witch depth the subs in WW2 could launch torps - so it could be cheating.

Edit: just checked out the unmodified settings from SH3 1.4: 20m. So it´s a little bit of cheating.

[Joefour]

Wouldn't that be cool if you could launch torps from a 100M depth at the escorts attacking you. SUPERSUB! Kill 'em all, let Churchill sort 'em out!

[Joefour]

@aras: if you want to try it, check the settings in the NSS_Uboat**.cfg (inside SH3/data/Submarine/NSS_Uboat**/) first.
This should work most times. I don´t know from witch depth the subs in WW2 could launch torps - so it could be cheating.

Edit: just checked out the unmodified settings from SH3 1.4: 20m. So it´s a little bit of cheating.
I am sure the depth limitations on launching torpedos has something to do with water pressure. It would be interesting to play around with the various types of subs, Allied or German, and see how much havoc you could create from below periscope depth.

I bet that modern atomic subs don't have anywhere near the same limitations. I would search out a today's submariner and ask him. But if he told me then he would probably have to shoot me.:haha:

[Paulebaer1979]

I am sure the depth limitations on launching torpedos has something to do with water pressure.
That´s right. We need blueprints from the subs to check the maximum depth. It´s dangerous to launch a torp at depth because the inner door of the torpedotube opens to inside the pressure hull. So the pressure of the water would open it or make it flooding if the sub is to deep with opened front door of the tube.

I bet that modern atomic subs don't have anywhere near the same limitations. I would search out a today's submariner and ask him. But if he told me then he would probably have to shoot me.:haha:

Even older and nonatomic subs can launch torps from depth deeper 100m. Class 206/206a were able to launch torps from 100m. That´s design depth for those subs. Class 212 can launch torps from design depth (250m), too. Both classes were build with nonmagnetic special steel which isn´t as strong as normal shipbuilding steel.
Class 209 and 214 (normal steel) can go deeper as 350m and i bet they can launch torps from that depths, too.

[Joefour]

That´s right. We need blueprints from the subs to check the maximum depth. It´s dangerous to launch a torp at depth because the inner door of the torpedotube opens to inside the pressure hull. So the pressure of the water would open it or make it flooding if the sub is to deep with opened front door of the tube.



Even older and nonatomic subs can launch torps from depth deeper 100m. Class 206/206a were able to launch torps from 100m. That´s design depth for those subs. Class 212 can launch torps from design depth (250m), too. Both classes were build with nonmagnetic special steel which isn´t as strong as normal shipbuilding steel.
Class 209 and 214 (normal steel) can go deeper as 350m and i bet they can launch torps from that depths, too.
Netflix had a show on the other night that I think, might have been off the Discovery Channel, about a modern american sub they were allowed to go out to sea on and film (with limitations in certains areas of the boat). Their fuel lasts for years, they make their own air and fresh water, the only thing that holds them back is the chow supply. Neat! Had no idea they could make their own water and air supply. Now if they could just requisition a replicator from Capt. Kirk they'd be all set.:)

[Paulebaer1979]

Netflix had a show on the other night that I think, might have been off the Discovery Channel, about a modern american sub they were allowed to go out to sea on and film (with limitations in certains areas of the boat). Their fuel lasts for years, they make their own air and fresh water, the only thing that holds them back is the chow supply. Neat! Had no idea they could make their own water and air supply. Now if they could just requisition a replicator from Capt. Kirk they'd be all set.:)

Yes. But you will need a replikator for torps, harpoons and so on, too. And don´t forget about the crew. You´ll need some woman to replikate the crew:woot:

And all those engines and systems are the reason why a LosAngelos sub fresh out the shipyard (refreshment) had no chance against a 30 year old 206a in med sea 2002. We won 20 to 1. The one time they found us, we started to snorkel while the batteries were fully charged. We were able to detect the noise from reactor from greater distances as the LA could detect us - even when both subs cruised with speeds below 10kn.

[Joefour]

Yes. But you will need a replikator for torps, harpoons and so on, too. And don´t forget about the crew. You´ll need some woman to replikate the crew:woot:

And all those engines and systems are the reason why a LosAngelos sub fresh out the shipyard (refreshment) had no chance against a 30 year old 206a in med sea 2002. We won 20 to 1. The one time they found us, we started to snorkel while the batteries were fully charged. We were able to detect the noise from reactor from greater distances as the LA could detect us - even when both subs cruised with speeds below 10kn.

This is true. Good thing thing I'm not employed as a naval planner!

Uh, you aren't going to have shoot me now, are ya?

[Paulebaer1979]

No i´m telling the truth. We had to officers from the LA onboard. They were surprised how easy we detected their sub.

Just ask yourselve why HDW sells subs as 209 and 214 as easy as a fresh rolls on a saturday morning? Because they are not easy to find, easy to handle and very agile when submerged.

[Joefour]

Yes. But you will need a replikator for torps, harpoons and so on, too. And don´t forget about the crew. You´ll need some woman to replikate the crew:woot:

And all those engines and systems are the reason why a LosAngelos sub fresh out the shipyard (refreshment) had no chance against a 30 year old 206a in med sea 2002. We won 20 to 1. The one time they found us, we started to snorkel while the batteries were fully charged. We were able to detect the noise from reactor from greater distances as the LA could detect us - even when both subs cruised with speeds below 10kn.

What I find interesting is the detectable noise you say was coming from the powerplants. Many years ago I worked with my dad at a pump factory in the Los Angeles area. They did some DoD work, the majority of which was submarine main seawater pumps, which I think was for Electric Boat in Connecticut. I have no idea what class subs these pumps were for. I worked there from 1973 to 1978, if that helps. The thing is, the pumps were so quiet that they had to be tested outside at a special testing station away from the machine shop noise. What amazed me was that you could stand next to them and not even know they were running unless you put your hand on them and felt a very smooth vibration.

[Paulebaer1979]

What amazed me was that you could stand next to them and not even know they were running unless you put your hand on them and felt a very smooth vibration.

That´s the fact. The reactor needs active watercooling above a spec. speed/load limit. We were able to detect this cooling pump about distances of 2-3,5 nautical miles. When we drove at the same speed, the LA-class sub wasn´t able to detect us at the same distance.

The 212 are better noise-isolated. All engines witch vibrates or make any noise are build in special location. This room is noise-isolated build and has special basics to the hull.
In facts they can detect a coastal cargoship at range about 80 nautical miles and another 212 sub cruising in normal modus only in range under 100m. Therefore HDW had a slogan: "Nobody finds our subs well."

[Panthera Pardus]

Ahoy,

Interesting tactic in your first Post, joefour. But it sound familiar while I read it, and at the End I know why. Because I am a fan of the movie "Periscope Down" since the first time I saw it. And when I think I have enough experience I truly will try it myself. But it is good to know that you tried it successfully. So, Thank you for posting it, have a nice day and good hunting.

Joy and Happiness
Panthera Pardus

P.S.: Just in case anyone wants to know, the German Title is "Mission Rohr Frei"

[Joefour]

Ahoy,

Interesting tactic in your first Post, joefour. But it sound familiar while I read it, and at the End I know why. Because I am a fan of the movie "Periscope Down" since the first time I saw it. And when I think I have enough experience I truly will try it myself. But it is good to know that you tried it successfully. So, Thank you for posting it, have a nice day and good hunting.

Joy and Happiness
Panthera Pardus

P.S.: Just in case anyone wants to know, the German Title is "Mission Rohr Frei"

I wonder why they didn't just call it " Seerohr Ab". Gut' Jagd!

[Joefour]

That´s the fact. The reactor needs active watercooling above a spec. speed/load limit. We were able to detect this cooling pump about distances of 2-3,5 nautical miles. When we drove at the same speed, the LA-class sub wasn´t able to detect us at the same distance.

The 212 are better noise-isolated. All engines witch vibrates or make any noise are build in special location. This room is noise-isolated build and has special basics to the hull.
In facts they can detect a coastal cargoship at range about 80 nautical miles and another 212 sub cruising in normal modus only in range under 100m. Therefore HDW had a slogan: "Nobody finds our subs well."

Amazing! 80 NM.

[Paulebaer1979]

Amazing! 80 NM.

Made in Germany:har:

And i was able to hear both, DEMON and LOFAR with the Flank Array.

DEMON stands for: DeModulationOfNoise and means the noise only from the prop of the target.

LOFAR means the lower frequences of the engines and gearboxes. With this tool you can analyse the number of cylinders of the engine, the number of turns per minute and the ratio of the gearbox. Very interesting stuff.

P.S.: Just in case anyone wants to know, the German Title is "Mission Rohr Frei"

Funny movie. One of four submarine movies i look regularly.