Problem with convoy approach (RFB+RSRDC)

[JANXOL]

Hey there,

I decided to go back to SH4 after some time, booted up my RFB install and went into the career to see how rusty I am. Apparently extremely rusty, as I can't even get into firing range on the convoy before I get detected.



I have tried to load the game and approach this convoy about six times and each time failed, so I thought I would pop in here and ask some experienced skippers.




Here's the situation and what I've done:
Night, no wind, no clouds. Patrolling designated area at 10kn surfaced, the game goes "CHUG - I just loaded some ships for you". Since I hate that, I wait about 10 game minutes before diving and doing a routine hydrophone sweep. Sure enough I hear a convoy, multiple merchants and escorts. I plot the angles on the map (in this case about 280-315). Surface the boat and turn towards them. My intention is to run for about 5nm, dive and listen again, to try to estimate their course and whether they're closer. After 30 minutes I see smoke on the horizon, so I turn, trying to get a parallell course to the convoy. It's not perfect so I do get slightly closer and begin to see the masts. As such I correct by turning away, but after a moment I can see that two escorts have left the convoy and are coming towards me. How the hell did they spot me at this range at night?

Regardless, I think I can still intercept the convoy. I turn to the intercept course and dive, going below the thermal layer. Battlestations, silent running, engine RPM goes below 100. (at no point during the submerged approach RPM exceeded 100). After some time I go up to periscope depth to take a peak. Two destroyers are looking for me behind me, merchant ships in front of me, about 8500yards. I am crawling forward at 1 knot and roughly 50RPM. Shortly afterwards, another destroyer (on from the convoy, not the ones searching behind me, turns towards me and starts steaming. Scope down, go deep. Then I get pinged and shortly after I have six destroyers depthcharging overhead.





This brings several main points and questions:
1. What is the range at which a surfaced submarine will be spotted? I was spotted way before my crew spotted and reported the convoy. I also heard RFB escorts don't exactly have x-ray vision.

2. What is the hydrophone range? I am fairly certain its not the one listed in the equipment tab, since you can hear convoys well beyond visual range.
3. What are good tips and tactics for sneaking past escorts and generally approaching the convoy?


All help is appreciated. Also, if it's important, I was in a Sargo-class boat.

[Aktungbby]

JANXOL!

[Fifi]

I think you should be more ahead of convoy, waiting right on his path with all stopped at periscope depth.
For that you need to shallow the convoy, estimate as close as possible his route, never approach below 10 Km, and full speed you go to the interception point you have estimate.
Best is to stand ready around 1000m of a convoy line. Right side or left side only matter the escort positions...
Sometimes they will detect you, sometimes not...so ready to launch or ready to dive deep and escape!

On side note it depends of what mega mod you are running.
While vanilla game remains easy, TMO or Ralles can be really tough

Good luck

[Barkerov]

1. I don't know exactly but its a combination of escort skill, your speed, your aspect and the weather.



Obviously, the higher the skill of the escorts the better chance they have of spotting you. In RFB, the early war escorts are pretty good compared to their middle war couterparts. Chance also plays its part here.


They also seem to be much much better at spotting you from distance when you're running at Full or Flank speed. This is what I think got you detected in this case. I remember getting spotted from great distance in 1941 on a calm night running in at high speed on a task force. Running at 1/3 to 2/3 I've gotten within 2000 yards on RFB + RSRDC before I chickened out and dived (that was probably against low skill escorts though as it was 1944 at the time).


I also remember reading somewhere on subsim that on the surface your aspect works the reverse to what you would think. I was expecting broadside = easy for bad guys to see, front on = harder for bad guys to see. Apparently it's the other way around and can't be fixed because it's hard coded.


Weather works how you think it should, bad weather = bad visibility etc.




2. Hydrophone range is a very unrealistic 20nm when you use it manually. Your crew hear at ranges that are much more realistic.




3. Best place to be is in their path. If you're not there, then go around at high speed with their smoke only just visible on the horizon. RADAR makes this much easier as you can keep them at 6nm +. I've never been spotted at that distance on RFB + RSRDC. For getting inside the convoy undetected, the trick is to not spend too much time in an escorts SONAR detection cone. The escorts are triggered by some sort of timer that starts once you're in the cone but I don't know exactly how long this is. I've had success going under the layer and driving into the convoy at 2/3 speed at an angle until the escorts pass by. I don't think they are listening for you until you get detected but someone undoubtedly knows better than me. The faster the convoy the better, since they pass over you more quickly.


Hope that helps some.

[jimmbbo]

I have had success steaming at high speed parallel to the convoy course at 7-10 miles away to a point where I can turn in to be at 90 degrees to the convoy course about 15-20 miles ahead of the lead escort. When I am confident of the convoy's course, I close to ~1000 yards at 90 degrees and check torpedo settings (10 ft depth, Contact/Influence setting and Fast or Slow speed depending on how I want to shoot them if a selection is available)

When the convoy reaches 6-8 mi range, I submerge to 200 ft, silent running and battle stations. When the lead escort moves to about 15 degrees off the bow, I come up to 150 ft, and as the escort passes the bow and I am out of their prime sonar detection zone I continue to periscope depth, opening the outer doors as I pass through 100 ft.


After deciding which merchants to target, I up set and take the shots, then immediately submerge to maximum depth. After passing the thermocline, I begin zig zagging while creeping at 2-3 kt toward the transports to mask my sub's noise among the merchants and set up another shot if the opportunity presents itself, jogging at least five miles away before surfacing if no firing opportunity arises...
Every so often a superman sonar operator will display uncanny skill and dog my boat unerringly with only shreds of information, at which time I scrub the mission, go deep, go quiet and get out of Dodge.

[KaleunMarco]

Originally Posted by JANXOL

This brings several main points and questions:
1. What is the range at which a surfaced submarine will be spotted? I was spotted way before my crew spotted and reported the convoy. I also heard RFB escorts don't exactly have x-ray vision.

depending on the mod, 6 - 7 nm on the surface. playing FOTRSU, i've been spotted further out

Originally Posted by JANXOL

2. What is the hydrophone range? I am fairly certain its not the one listed in the equipment tab, since you can hear convoys well beyond visual range.

that's an excellent observation. like real life, sonar reception depends on many things. no need to go into minute details. use the published specs as a base line. if you detect further out it is a bonus.

Originally Posted by JANXOL

3. What are good tips and tactics for sneaking past escorts and generally approaching the convoy?

as some of the others have indicated, try to get in front of the convoy's base track while on the surface because you can make much better speed on the surface. do your surface outside run at least 7 nm from the DD's on whatever side you are on. try to make it more than 7 nm if possible. use the nomograph to calculate how much ahead of the convoy you need to be in order to be in good firing position. then dive, below the thermal later if possible. make your approach, trying to stay behind the dd's. when they (DD's) pass rise to periscope depth, fire as many torpedos as you have time and then dive under the therm. when you do that, decide whether you are going to try and make another run at the convoy or just escape and hunt somewhere else. if you are going to re-engage, try and use the same philosophy as you just used.
keep in mind the old naval adage: no plan lasts longer than the first shots fired.
you will need to learn what your boat and crew can accomplish and what they cannot accomplish and then keep refining your battle technique.
good luck.

[Sniper297]

What Fifi said.

"The big problem is to get in front of the target.
Anyone ought to be able to hit him with a torpedo after that.
Getting into attack position is ninety percent of the job.
Captain Blunt, RUN SILENT RUN DEEP"

The END AROUND is the most important part of the approach phase, first figure out where he's going, draw the target track line out several hundred miles, then move away from the track - 10 miles is probably best. After you're ahead of the target you can gradually start turning toward the track, always staying at least 10 miles outside the visual range and watching out for escorts doing a sweep to look for evil pirates in submarines doing exactly what you're doing. When you're directly ahead of the target (I start on the track and move off it to one side or the other when I've confirmed what the exact track is) submerge and maneuver slowly to attack position.

It helps if you think of a WWII sub as a self propelled minefield, you can't move very fast or very far underwater, so move fast on the surface outside visual range to place yourself ahead of the target, then submerge and wait for them to run over you.

Again, this bears repeating - the actual attack is only 10% of the battle, 90% is the plotting and approach phase.

[JANXOL]

Thank you for all the input and advice. I have now finished that patrol, and in hindsight, it was either skill or sheer amount of escorts on that convoy to make it impossible to get close. I have attacked 3 other convoys during that patrol, and had much less trouble with sneaking up on them.



I guess my main problem now is the mk16 being a marvel of technology...

[TS13]

I also remember reading somewhere on subsim that on the surface your aspect works the reverse to what you would think. I was expecting broadside = easy for bad guys to see, front on = harder for bad guys to see. Apparently it's the other way around and can't be fixed because it's hard coded.

Oh dear, is this true? Can other people confirm?

[The Kraken Wakes]

Hi there, I only joined subsim last week. I have read a bit about the Battle of the Atlantic and how things were done. Some of their boats could dive to 750 feet. At that depth there is 23 times atmospheric pressure which equates to 318 pounds of pressure per square inch on the hull. In spite of that, one way was to work out their course and speed, set up a kill zone ahead of them, get there first at max depth with engines off completely, wait for the escorts to pass overhead, make a timed ascent to periscope depth with engines off above the thermal layer, and you are then INSIDE the convoy and can work torpedo shots in a 360 degree radius. By the time the impacts start occurring you are already gone. I have used this regularly with quite a lot of success. 232000 tonnes sunk in 2 attacks before I ran out of torps. Hope this helps.

[KaleunMarco]

Originally Posted by TS13

Oh dear, is this true? Can other people confirm?

that is not my experience.
other players may have mistaken profile for increased accuracy by the enemy surface ships or aircraft.
make no mistake, enemy surface ships and aircraft are much more accurate than your gunners.

do not attempt to shoot-it-out with enemy surface ships. that is the fast path to davey jones' locker for you.

good luck!

[Aktungbby]

Originally Posted by The Kraken Wakes

Hi there, I only joined subsim last week. Hope this helps.

The Kraken Wakes!