convoys convoys uuuggghh

[midnightrider1818]

ok fellow sailers. so I am on patrol 5. sunk one large cargo. its jan 3 1940 and I decided to take a look at the convoy map and decided to head to the north part of Ireland where all the convoys routes come together. About a day or two after I got there I picked up a convoy on my hydrophones but they were heading in and I was in to shallow of waters to do a attack. I thought aaahhh hhaaa. this is where my convoys are. moved out into deeper waters just on the north side of Ireland. been staying submerged most of the time to try to pick up another convoy and nothing. I have been here now probably two to three weeks and nothing. how often do convoys come in and out of here. also where is a good place to hunt for convoys at.

[Lokisaga]

The area between Rockall Bank, northwest Ireland, and the Hebrides is a good place to patrol, usually. Historically, early 1940 was just a rather quiet time. The winter of 1939/40 was unusually cold and stormy in Europe. Most of the Baltic froze and many ships were stranded in port. In my experience, the game models this by having very few ships sailing around during this time. Don't worry too much. Even Prien had a "dry" patrol. I recommend regular dives to check for sound contacts; you can hear a lot farther than you can see. Also, your hydrophones are more effective the slower you're going and the deeper you dive. Remember, the ocean's big. Really big. At best, you can see stuff 16 km away and hear stuff 20-25 km away. There's a lot out there that you're just never going to find.

[Jimbuna]

250km west of Gibraltar

[banryu79]

Originally Posted by Lokisaga

The area between Rockall Bank, northwest Ireland, and the Hebrides is a good place to patrol, usually. Historically, early 1940 was just a rather quiet time. The winter of 1939/40 was unusually cold and stormy in Europe. Most of the Baltic froze and many ships were stranded in port. In my experience, the game models this by having very few ships sailing around during this time. Don't worry too much. Even Prien had a "dry" patrol. I recommend regular dives to check for sound contacts; you can hear a lot farther than you can see. Also, your hydrophones are more effective the slower you're going and the deeper you dive. Remember, the ocean's big. Really big. At best, you can see stuff 16 km away and hear stuff 20-25 km away. There's a lot out there that you're just never going to find.

As Lokisaga said.
And because of that, it is a very good idea to try to plan & plot a sensible search pattern along the choosen area, with well thought out speed/time span to run on the surface VS speed/time span to run submerged. The aim is to optimize the covering of your area while minimizing the chances of losing any passing-by contact in the area.

[BigWalleye]

Originally Posted by banryu79

As Lokisaga said.
And because of that, it is a very good idea to try to plan & plot a sensible search pattern along the choosen area, with well thought out speed/time span to run on the surface VS speed/time span to run submerged. The aim is to optimize the covering of your area while minimizing the chances of losing any passing-by contact in the area.

An effective search technique (and one that was used historically) is to plot a zigzag course moving along a known or suspected shipping lane. The legs should be about 50 km long, less if listening conditions are poor. The zigs should be 60° to each other. Move on the surface at Standard speed, about 10 kts. At the end of each leg, dive to 30 m (or less if the water is too shallow ) and slow to 2 kts. Listen for a couple of minutes, then turn 90° to one side. (This is called a "clearing turn" to check the sector directly behind the sub where the hydrophones can't hear.) When you reach 90°, go to Ahead Standard, return to course, and surface the boat. Tusns at the ends of the zigzag legs should be 120°. This search will cover a path 100 km wide with good probability of detecting any ship moving along it at 10 kts or less. To catch faster ships, or in poor listening conditions (like bad weather), narrow the search pattern legs. You can also do a search dive in the middle of each leg, although this will leave gaps along the outer edges.

It is important to realize that the hydrophones will always detect ships at much greater range than you can see them. But for the hydrophones to be effective, you must be deep (30 m if you are using Rubini's hydrophone layers mod) and barely moving. But you can't cover much area that way. The sprint-and-listen approach - which is also what escorts use when hunting you - doubles your search area.

[Pisces]

And don't go overboard with timecompression. Or else the convoy can leap-frog over your sensor area undetected. More likely with singles and aircraft. But could happen with convoys on the outskirts of your sensor area also.

[flag4]

Originally Posted by Jimbuna

250km west of Gibraltar

+ BE MORE AGRESSIVE ?

[banryu79]

Originally Posted by BigWalleye

...
The legs should be about 50 km long, less if listening conditions are poor. The zigs should be 60° to each other. Move on the surface at Standard speed, about 10 kts. At the end of each leg, dive to 30 m (or less if the water is too shallow ) and slow to 2 kts. Listen for a couple of minutes, then turn 90° to one side.
...

Very nice, thank you BigWalleye!
Do you know where I can find/read detailed historical info about the search patterns used? I'm very intrested in this matter

[Jimbuna]

Originally Posted by flag4

+ BE MORE AGRESSIVE ?

OH yes

BE MORE AGGRESSIVE!!

[flag4]

...hmm - thought that might be in there somewhere

[vanjast]

If you consider that your average convoy speed is 8 knots, and you should hear (hydrophone) a large convoy up to 100Nm (AFAIK not sure if this is modeled but it doesn't matter) on a good day.. this gives approx 12 hours to traverse this distance. If you idle along at 7 knots in the opposite direction.. your total closing speed is 15 knots, giving you 6 hours.

On a bad day your hydrophone distance should be less, but so should your and convoys speed be less... so six hours is a good balance between detection and irritation.

What I do is run square box patrol at 6 hours per leg (any speed < 7knots will do) and at the end of each leg dive for a hydrophone scan, turn 90 listen again then surface for the next leg.

Get very tedious, but I've picked up convoys at long distances.

[Pisces]

'Reality check'

SH3 has a hard capped hydrophone range of about 34 km radius if you listen manually at the hydro station. That's still a needle in a vast ocean.

[banryu79]

Originally Posted by vanjast

...
What I do is run square box patrol at 6 hours per leg (any speed < 7knots will do) and at the end of each leg dive for a hydrophone scan, turn 90 listen again then surface for the next leg.
...

Thank you, nice patrol strategy.
Until now I never thinked about "sqare box" patrol legs... I had always used "triangle" (or zig-zag) legs... I will try this strategy.

Originally Posted by vanjast

...
Get very tedious, but I've picked up convoys at long distances.

Yeah, I know what you mean but I bet it is more tedious and frustrating to run around at random and still not picking up any contacts at all. For me it's always better to try and maximize my chances to hear/spot them even if in the end I do not found anything.