For bold u-boat skippers only!

[Phaedrus]

Staying near the surface works in rough seas.

My idea of a perfect convoy attack is a silent running 2 kt approach at periscope depth, 90 degree angle of attack.

Given a 20 ship convoy, in 5 rows of 4, I want to be two rows inside the convoy, with at least 400 M between row two and my aft tubes. This puts row 3 crossing my path at about 600 m or so. All stop at this point.

The escorts long since moved by, the lead ships now reaching about bearing 340.
Silent running off.
First shots are the meaty (tanker, whale, cruiser) targets at the rear flanks of rows 4 and 5; shooting at bearing 270-300 at a range of perhaps 3000 - 4500 m, farthest target first, two torpedo magnetic salvos running 1 - 1.5 meters below the draft.
The angle the ships are on is a terrible shot for an impact, but it exposes the magnetic head to more of the ship, increasing probability of a hit. There is no danger in firing on such a terrible angle because the convoy is moving in a straight line - we are undetected.
Aft tubes are out in another two torpedo, magnetic salvo at a decent target of similar, but slightly less range in row one or two.
Its about a 3-4 minute wait for impact.

Tube one reloads just before initial impacts. I prefer T1's at this point, because I can set them to run fast. Tube one takes a lead ship in row three, possibily row four on impact because they will soon start the zig zag. Aft tube four takes the lead ship, which is now fast approaching 180 degrees, on fast and impact.
Both of these shots should be aimed at the bow to facilitate flooding.

Properly timed, we should have impacts on 5 ships. Three almost certainly fatal, and two that should be eventually fatal as the lead ships tend to be medium to small tonnage, and flood easily in rough seas / destroyed bows.

At this point it's time to check the hydrophones / periscope and see what the escorts are doing.

If all is well, tube five and two should be ready to either put another nail in the coffin of the first two ships you hit, or if you have time... to wait until the next ships in rows 2 and 3 come into near 90 angle of attack shots. Both tubes should be running fast and impact. I am skeptical of the reliability of magnetics unless they're salvoed. If you decided to wait, you should be able to hit your target despite the zig zags - they are too close to shake the 40 kt torpedo. Aim for the bow and you have a wide margin of error. The odd time you'll get a bounce off due to a bad angle..... but c'est la vie.

With 8 forward fish gone, 4 aft, it's time to leave. Escorts should be on the way in, usually one from center of the convoy on your starboard side, and one or more from aft.
Periscope down, all the way into the housing.
We want to be on the move before they are within 4000 m. Back into Silent running, new depth 22 meters. (this is only in rough seas! If it is glass calm, you had best find your way into the cellar quickly. I loathe calm convoy attacks)

In either case, rough or calm, our exit point is the same - only the depth has changed.

We are aiming to leave the convoy at its port-astern quarter... the left rear.
This puts my big IXC at a good angle for deflecting sonar from the closing escorts, now on my left and right astern sides and closing fast.

It is advantageous to leave in this direction because of the convoy itself.
Remember how we placed ourselves between row two and three? We are now two ships deep and still between row two and three, but on our way out silently.

This provides an effective screen as the escorts have to break contact to avoid colliding with the zig zagging convoy. (I am also pretty sure that at least one merchant to my tally has killed by depth charges from a destroyer. Bonus points if that happens)

You should be able to slip right out the back without ever having been seriously engaged. You might get pinged, but resist the temptation to speed up. He's just looking for you, he hasn't found you.

I should note that the odd time if I am concerned that I stuck around too long to get my last shots off ("Load faster you morons!") I will sometimes drop a decoy in my wake in the center of the zig zagging convoy. The escorts have to try to fight their way to it through the moving convoy, and usually by the time they get there it burns itself out, leaving them to depth charge the decoy area, or proceed in a search pattern in a what ever direction they happened to be facing when they finally penetrated the convoy screen.

I have found success with this method, playing with a big IXC with the alberich coating, late 1940 to my current time, February 1943.
Above all, safety first. I am more concerned with surviving and not having to start a new patrol than I am sinking another freighter....

Anyway. Thats just how I roll.

Experiment to find your own pattern for success.
Hope it helped.


Edit: Nuts. I had multiple forum threads open at the same time, and I managed to reply to the wrong post.

It still kind of works in this one as well though, so I'll leave it be.

Moral of the story: Shallow water works based on conditions.
Rough seas, and a convoy to run interference for me, I'll do it all day..... or at least, I'll do it until later on in the war when conditions might force me to change - I've only gotten as far as early 1943, and I haven't yet hit the dreaded month of May.

Regards,

Phaedrus

I've started looking into this several weeks ago. It's one of the things I intend to experiment with once I've caught up with all my other mod projects.

As an aside, I'm working on the angle of depth charges leaving behind pockets of 'noise' after they explode. Which is what they really did. It took between 10 - 15 minutes after a DC attack for that noise to disappate and for escorts to try re-acquiring contact again. Quite often a U-boat could evade and creep away during that time.

The mod I'm working on shows a lot of promise so far with that. It's being alpha tested for now (anything dealing with AI behavior --sensors in particular-- requires a lot of testing) but, so far, things are looking quite good!

[Platapus]

Check out http://uboat.net/articles/index.html?article=45

Negative refraction: during the summer temperature of water decreasing by depth of the water. Sound wave is bending towards the sea bottom. If submarine is on smaller depth, near the sea surface, sonar can’t detect the submarine. Range of the sonar is bigger if the submarine is merged on deeper depth.

Still a pretty gutsy thing to count on.