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-   -   Night surface attack (TWOS) (https://www.subsim.com/radioroom/showthread.php?t=249370)

Markus Witt 05-04-2021 01:03 PM

Night surface attack (TWOS)
 
I just tried to attack a convoy at night on the surface, no moon, fully dark. My forward tubes had all electric torpedoes meaning I had to get fairly close. So I approach the convoy from it's portside and slip past the escort on the port shoulder. I get into a firing position and fire 4 torps. Now it's time to get out of there, so I make a U-turn and go to flank speed. I have not been detected and as I get on my new course at flank speed I'm still undetected. Then the first torpedo strikes.

Within a fraction of a second every ship in the convoy has a searchlight switched on aimed directly at me and within a second every ship starts firing at me accurately scoring direct hits. Before I can crashdive the control room is filled with mist and is flooding and we plummet straight down to our doom with no chance to stop the descent and it's career over.

Bloody hell, this is ridiculous! :o Is it even possible in TWOS to carry out a surface attack? I've done it succesfully with steam torps from long range but with electrics it seems impossible as you have to get closer. The ability of the merchants to immediately know where I am and to open fire on me within a second seem to make a close surface attack impossible. Is there a way to tone down this magical ability of the merchants?

les green01 05-04-2021 01:38 PM

i just got though with a 20 ship convoy right up the middle playing march 40 fire off all eels then reloaded the last two while they was reloaded i reacted the greatest ace of all and use the deck gun while waiting on the 2 eels to load then went out after fire the last two eels

Markus Witt 05-04-2021 03:45 PM

I loaded a save (autosave just before the attack started) and tried again. This time I scored 4 hits and as I sped away at flankspeed there were no searchlights. No idea why not, it was the exact same attack. Attack takes place in May 1941 by the way (TWOS 2.17). This time it looked like I might be able to escape on the surface. But then the closest escort came racing in. As it was passing astern of me I hoped it would pass by without seeing me. But then a searchlight came on and shortly thereafter it fired at me, forcing me to crashdive. At least I was not hit this time before I could dive. Don't mind being found by the escort, that at least makes sense.

A depthcharge barrage followed for 30 minutes, resulting in minor damage. Various escorts kept circling me for 1.5 more hours therafter and then disappeared. So it is possible to do a surface attack and survive. But I have no idea why both attacks gave such different responses by the merchants. The first response was ridiculous and gave me no chance whatsoever.

I will try this same attack a few more times with the old save to see what will happen and if I can manage to escape on the surface.

les green01 05-04-2021 05:40 PM

Quote:

Originally Posted by Markus Witt (Post 2745989)
I loaded a save (autosave just before the attack started) and tried again. This time I scored 4 hits and as I sped away at flankspeed there were no searchlights. No idea why not, it was the exact same attack. Attack takes place in May 1941 by the way (TWOS 2.17). This time it looked like I might be able to escape on the surface. But then the closest escort came racing in. As it was passing astern of me I hoped it would pass by without seeing me. But then a searchlight came on and shortly thereafter it fired at me, forcing me to crashdive. At least I was not hit this time before I could dive. Don't mind being found by the escort, that at least makes sense.

A depthcharge barrage followed for 30 minutes, resulting in minor damage. Various escorts kept circling me for 1.5 more hours therafter and then disappeared. So it is possible to do a surface attack and survive. But I have no idea why both attacks gave such different responses by the merchants. The first response was ridiculous and gave me no chance whatsoever.

I will try this same attack a few more times with the old save to see what will happen and if I can manage to escape on the surface.

good luck i try to keep a low profile and wake down much has possible i'm playing the latest TWoS update it after playing for awhile the game i think gets corrupt and start acting up so i save and relog has much as i can

kapuhy 05-05-2021 03:08 AM

Quote:

Originally Posted by Markus Witt (Post 2745989)
But I have no idea why both attacks gave such different responses by the merchants. The first response was ridiculous and gave me no chance whatsoever.

Luck factor I'd guess.

What happens when your torpedoes go off is all nearby ships instantly change their crew state from "Cruise" to "Alert", increasing their ability to detect you - so even if you were quite safe a second before, now you might end up in their "detection range". Then there's the luck factor: being inside detection range doesn't mean instant detection, it means they get random time in which they will spot your boat. It may be a second, or it may be enough for you to move out of dangerous spot. And at night, then there's spotlights (haven't looked into how they work but I guess being in spotlight drastically cuts down on time they need to detect you - and since they scan with those spotlights randomly, there's again a random chance that they just happen to point it in right direction and see you instantly).

Markus Witt 05-05-2021 05:05 AM

I tried the same attack several more times. I was never able to escape. Tried everything, flank speed at various courses, going to decks awash after the first torpedo strike. Nothing worked, the escorts found me every time. One time it took them a bit longer and I had some hope, but nope they detected me anyway. However I never got the extreme reaction of the merchants again. Not sure why, perhaps I was on the edge of their detection range and got just inside that range the first time?

Based on torpedo running time I launched my attacks from about 2200 meters outside the outer convoy column. That's a little closer than I thought it was. I tried the attack again and this time increased the range a bit. Based on torpedo running time I was now 4500 meter outside the outer row, just within maximum range (5000m) of the torpedoes. After launching I made a U-turn and went to flank speed. This time I was able to escape easily. I could see the escorts searching behind me with searchlights but they never came close.

So it is possible to carry out a night surface attack with electric torpedoes, but you have to stay at extreme range. Which is quite difficult to judge, since rangefinding with the UZO doesn't really work.

Markus Witt 05-05-2021 08:53 AM

1 Attachment(s)
Yeah, so you can use the UZO for rangefinding. Marks on the UZO should be used the same as marks on both periscopes with 6x zoom. During another attack the torpedo had a running time of 298 seconds. That's a range of 28 * (1852/3600) * 298 = 4293 meter. Just before firing I took an angular height measurement with the UZO. Since I looked at the target at a bearing of 18 degrees SB, the range at that moment was 4293 / cos18 = 4513 meter. (it was a zero degrees gyro angle shot, so torpedo travelled 4293 meter, but target was at 4513 at the moment of firing.)

Mastheight of vessel was 42 meters so that means I should have measured (42 * 100) / 4513 = 0.93 centirad. That is 4 * 0.93 = 3.7 marks on the UZO. If you look at the attachement that 3.7 looks about right. Difficult to see in the darkness as waterline and mast are not really vissible (mast is higher than the funnels).
So you can measure range with the UZO at night but it is not easy in the dark with moving UZO.

Markus Witt 05-05-2021 09:55 AM

After some more tries it seems you need a running time of about 4 minutes to have enough time to get away from the escorts undetected. During one attack running time was 250 seconds (range 3600m) and I got away, could see the escorts behind me at medium range throwing depth charges. During another attack running time was 220 seconds (range 3170m) and I was detected.

So you need to be about 3500m outside the convoy and need about 4 minutes to get away. I'm sure this depends on various factors and varies per attack. But, a succesful surface attack at night with electrics is possible, although the margins are fine. If you overestimate the range you're in trouble.

kapuhy 05-05-2021 03:49 PM

Quote:

Originally Posted by Markus Witt (Post 2746108)
So you need to be about 3500m outside the convoy and need about 4 minutes to get away.

This convoy, in this weather. Might be quite different with another one, since as you've yourself noted it's dependant on many factors, some of them randomized. But, still nice to have a baseline to start from :)

Markus Witt 05-05-2021 04:06 PM

Quote:

Originally Posted by kapuhy (Post 2746162)
This convoy, in this weather. Might be quite different with another one, since as you've yourself noted it's dependant on many factors, some of them randomized. But, still nice to have a baseline to start from :)

Yeah, it was just a test to see if it is possible at all. Like you say, this is just one test under certain conditions that will be different next time. But at least we know it is possible to do it if the conditions are right.

Storm501 05-14-2021 05:34 PM

I agree completely that surface attacks in TWOS are harder than historical. At least in 1939-41. Few reasons:

1) Convoy ships are packed more dense than historical. So it is not really possible to sneak inside the convoy and start torpedoing from the inside. (Kretchmer)

2) AI reaction time/system is ridiculous. As you mention all search lights focus on you in fraction of a second. In reality there would be a lot more confusion and searching.

3) AI gunnery is sniper accurate. Even if spotted, U-boats were difficult targets at night in deck awash.

Only point 3) can be edited as far as I know. It is possible to increase the scatter of AI gunnery. I recall that I tripled the scatter value. Now it is what I consider realistic. It is lethal, not not pinpoint.

So surface attacks are indeed difficult. With stealth it is possible to get as close as 3000 from escorts on surface to fire. However as you pointed out any escape is close to impossible. Only at ranges of 5000m there is a moderate chance to avoid detection.

My personal style similar to a torpedo boat: Fire at 4-5km range at flank speed with slow torp. Thus I have about 5 min to turn away from the convoy, increase the range to 8 km. 1 min before torp hit or if searchlights go deck awash. That way if spotted, dive time is reduced to a fraction.

les green01 05-14-2021 07:55 PM

only thing i can say i must be lucky i made two up the middle convoy attacks hadn't made it to 41 yet


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