submarine survivability again

[el cid again]

I am considering two measures:

1) defining DC in patterns of 2 - a single rack always drops twice - a Y gun always fires two rounds - and K guns generally come in pairs - firing to opposite sides. Thus we will get DD xyz firing 2 pairs of Type 95 DC.

2) Defining hull thickness reduced by a K factor as deck armor and side armor (the same for both)
this will help vs gun attacks for sure - and it might help vs DC attacks - if armor is a factor

[herwin]

ORIGINAL: el cid again

I am considering two measures:

1) defining DC in patterns of 2 - a single rack always drops twice - a Y gun always fires two rounds - and K guns generally come in pairs - firing to opposite sides. Thus we will get DD xyz firing 2 pairs of Type 95 DC.

2) Defining hull thickness reduced by a K factor as deck armor and side armor (the same for both)
this will help vs gun attacks for sure - and it might help vs DC attacks - if armor is a factor

The submarine hull design parameter is implosion depth, with ASW weapon effectiveness being evaluated in terms of the overpressure they generate at various distances and of their accuracy. See chapter 5 of Morse and Kimball (or the corresponding section of your favourite OR text) for a discussion.

[Historiker]

In WitW, I gave the German electro subs significant armour. The were nearly never surfaced, even their batteries were recharged submerged. Submerged they were even faster than many escorts and more quite and agile than every conventional sub.
But how can this points enter the witp data? I saw no other possibility than giving them armour to weaken both the impact of ASW planes and ships...

[el cid again]

It remains to be seen if armor helps. Likely it is NOT a factor in ASW attacks. But it might be. Durability is a function of depth - and it also is related to cost and build time - and this is very unfortunate. We cannot rate sub durability properly without terrible impacts because of it.

What DOES help is to keep the sub under water. In WITP do this by using Andrew's "snorkel" - a radar with range of zero. It detects a plane and the sub instantly submerges. In WITP subs NEVER travel under water.

Regretfully Type xxI subs do not move fast underwater. They just seem to if you look at speed data. On batteries they can sustain speed only a short period - and by the time they are available - using a snorkel is almost fatal. It will be spotted by high frequency radar on aircraft. The other problem is noise - running engines underwater is several times lounder than running them on the surface - any enemy with sonar in the area is going to hear the sub - but the SUB itself cannot hear ANYTHING. Snorkeling is not ideal by any means. Yet another issue is the snorkel itself - they don't work at any speed worth mentioning. Call it 10 knots for game purposes - and it won't even be that when you take damage. But more than that is science fiction - it is still a problem. One type vII went to Argentina in 1945 - but it took months - and averaged about 4 knots.

In RHS subs fitted with snorkels get a slower cruising speed - and a longer range - since they are assumed to try to cruise on snorkel - and this is never more than 10 knots sustained. FYI the "snorkel" device is a very odd one - it is an air search radar - and it makes the sub harder to find and kill - invented by Andrew Brown for CHS - it works - so we use it. But RHS added the "feature" of it makes you slow. 5 knots might be better (a ship often loses several knots to currents and other problems, and sustaining 10 knots is not really normal underwater) - but I felt 10 was a better compromise and would irritate players less. You can now choose between snorkling or not by the choice to move full speed or cruising speed - which is fairly correct. Late in the war - your survivability is so bad that the snorkel is almost necessary - no matter how badly it slows you down. One more thing - it is hard on a crew - and probably should result in a lower skill rating - but I never thought of that before.

[el cid again]

What I did in the past was add radar and snorkels.

What I did in the current release is reduce the effectiveness of DC.

I am trying to think of something more - in case that turns out not to be enough. A contingency plan.

[Historiker]

It remains to be seen if armor helps. Likely it is NOT a factor in ASW attacks. But it might be. Durability is a function of depth - and it also is related to cost and build time - and this is very unfortunate. We cannot rate sub durability properly without terrible impacts because of it.

It can be done - like I did in witw.
Take the durability of a ship, that seems to be correct by every means - so building time as well as survivability as well as building costs.
Now compare this costs with the costs for the sub and give the sub the correct durability. This might be 5-10 now, so much to less if durability is the function of deepth.

But now, let the new sub immediately upgrade to a sub with the correct durability after it's completed.
Doing this, both building time and costs are correct while the sub has the correct durability.

All you need for this is some calculating and one free ship class slot for every sub.

[m10bob]

In Steel Panthers I was able to pretty much simulate those small "Goliath" type robot tanks by giving them a size of "0", because ability to spot and hit was altered by the factor of size.
I wonder if this might have any relevance to the subs in WITP? IE, can the numbers be altered to make them less visible?

Ron Saueracker suggested armor on subs maybe 2 years ago, and I thought it was a good idea, and in spite of the fact the subs did not really have that armor, it did reduce the numbers of sunk subs, and (to me) it did represent how water slows ballistics..

[el cid again]

ORIGINAL: Historiker

It remains to be seen if armor helps. Likely it is NOT a factor in ASW attacks. But it might be. Durability is a function of depth - and it also is related to cost and build time - and this is very unfortunate. We cannot rate sub durability properly without terrible impacts because of it.

It can be done - like I did in witw.
Take the durability of a ship, that seems to be correct by every means - so building time as well as survivability as well as building costs.
Now compare this costs with the costs for the sub and give the sub the correct durability. This might be 5-10 now, so much to less if durability is the function of deepth.

But now, let the new sub immediately upgrade to a sub with the correct durability after it's completed.
Doing this, both building time and costs are correct while the sub has the correct durability.

All you need for this is some calculating and one free ship class slot for every sub.

Now that is clever. Have your cake and eat it too. Lots of work here - there are lots of sub classes.

Nevertheless- it only solves the cost problem. The sub is still to easy to sink - ah - but we can do this: use crush depth INSTEAD of test depth - THAT will work.

[el cid again]

ORIGINAL: m10bob

In Steel Panthers I was able to pretty much simulate those small "Goliath" type robot tanks by giving them a size of "0", because ability to spot and hit was altered by the factor of size.
I wonder if this might have any relevance to the subs in WITP? IE, can the numbers be altered to make them less visible?

Ron Saueracker suggested armor on subs maybe 2 years ago, and I thought it was a good idea, and in spite of the fact the subs did not really have that armor, it did reduce the numbers of sunk subs, and (to me) it did represent how water slows ballistics..

Ron's idea was adopted by CHS - I hated it and took it out - and I don't think he got any credit for the idea. It will work vs guns- and I do have problems with a MMG hit "penetrating side armor" too - but I don't think it does much vs DC. It MIGHT though.

[Historiker]

ORIGINAL: el cid again

ORIGINAL: Historiker

It remains to be seen if armor helps. Likely it is NOT a factor in ASW attacks. But it might be. Durability is a function of depth - and it also is related to cost and build time - and this is very unfortunate. We cannot rate sub durability properly without terrible impacts because of it.

It can be done - like I did in witw.
Take the durability of a ship, that seems to be correct by every means - so building time as well as survivability as well as building costs.
Now compare this costs with the costs for the sub and give the sub the correct durability. This might be 5-10 now, so much to less if durability is the function of deepth.

But now, let the new sub immediately upgrade to a sub with the correct durability after it's completed.
Doing this, both building time and costs are correct while the sub has the correct durability.

All you need for this is some calculating and one free ship class slot for every sub.

Now that is clever. Have your cake and eat it too. Lots of work here - there are lots of sub classes.

Nevertheless- it only solves the cost problem. The sub is still to easy to sink - ah - but we can do this: use crush depth INSTEAD of test depth - THAT will work.

You can even double the crush depth to increase their survivability. They'll bring more Victory points, but who cares? They will also take longer to repair, but I personally would accept his if it lets them survive longer!

[el cid again]

You meant double the test depth - and that is the Kriegsmarine standard. For the USA it is 150 per cent. (test depth = 2/3 of design depth).
RN uses 4/7 of design depth. Crush depth is slightly greater than design depth, but it is actually unknown - and I think we will just use design depth - which is established and defined.

That means the US gets 150 per cent of present ratings - Germans get 200 per cent - and RN 175 per cent. Japan is a puzzle - but I assume 150 per cent until I learn better.

[Historiker]

No, I ment you can give the subs as much durability as you want if you use my idea of "construction classes". Together with armour, it shall be possible to make subs significant stronger.
The only disadvantege will be a huge increase of victoriy points and a much more difficult repair-

[el cid again]

I don't think we need armor. Make one change at a time - and see how it works - to understand the impact.
Maybe later.

ALLIED subs can be rated for durability directly - they don't pay construction costs.

EXISTING Japanese subs same same.

Only NEW Axis subs need a different rating to build - then upgrade to use.

That is a problem for the Germans - they cannot upgrade where they appear - so we must make them start at Singapore or Soerabaja.
But otherwise - it works.

HOW to rate the subs for build costs?

There are three ways:

1) Time - build time in days divided by 10

2) Displacement - displacement divided by 400 - 200 or 100 - depending on what you think is most appropriate

3) Pro rated - so you consider both time and displacement. Using the most common sub in PTO as a standard, it took 11 months to build (330 days) and was about 1800 tons (cost 18, 9 or 4.5 - depending on standard chosen). 33 x 18 = 594. The nearest value that works in the game is a cost of 8 (8 x 80 = 640). [I chose 100 tons per point - like a tanker - a sub is complex and has lots of pumps, piping and tanks, like a tanker does] OK - if that is a reasonable total cost we can say "divide by 100 tons, multiply times .44 - and round off - to get the durability for the sub in its build cost form"

For the fighting form I am thinking we use

USN and Japanese durability (depth defined) times 1.5
British durability (depth defined) times 1.75
KM durability (depth defined) would normally be times 2 - but that isn't enough - since they had a real crush depth so much greater than design depth - never less than 200 meters (660 feet) - while design depth is 500 feet - so that suggests we use a bigger number. German subs had real crush depths as great as 280 meters. If we use 230 meters as typical - that is 750 feet - we end up with times three.

[el cid again]

Using time as the basis for cost means that gigantic submarine aircraft carriers cost less than many lesser vessels - since they were built fast.

Using displacement as the basis for cost is similar to all other ships - but then the game costs get excessive. We would have 18 for 180 days in the example above - instead of 8 for 80 days. The composite system results in lower cost impacts while preserving relative differences between classes.

Yet another factor might be that sub transports designed as such - simple vessels - cost half what a regular attack sub costs.

Opinons requested.

[ChezDaJez]

Nevertheless- it only solves the cost problem. The sub is still to easy to sink - ah - but we can do this: use crush depth INSTEAD of test depth - THAT will work.

I think that you are missing the key point. Subs SHOULD be easy to sink... they were fragile things. In the game, it is the accuracy of the attack that primarily results in high subs losses, not the way the sub is modelled. And this involves external factors.

Let me explain. IRL, a submerged sub often escaped serious damage despite enduring multiple depth charge attacks. If you read the Clay Blair's "Silent Victory", he relates that U.S. subs were depth charged on a significant number of occasions without incurring substantial damage. In the Atlantic, most German subs also endured mutliple attacks and remained operational. Indeed, in most occurances, it took multiple attacks over a period of hours, sometimes days, to bring about the destruction of the sub. Depth charges attacks were one of the least accurate attack methods employed. Even after the advent of other ASW weapons such as the Hedgehog, the accuracy of the attack was still poor due to the inherent difficulties of using sonar to accurately predict a sub's location and depth sufficiently to bring about a successful attack. The primary advantage of the Hedgehog was that it did give confirmation of a hit.

In the game, attack accuracy appears to be too high. And I believe this is because depth charges are modelled similar to bombs where each individual weapon is given a chance to hit rather than the pattern as a whole. So the more DCs dropped in a single attack, the greater the chance of multiple hits in the game when in reality the most hits that could be expected from any one DC attack was one. This was due to the need to cover a large area with a DC pattern to offset the inacuracy of the attacking ship's sensors.

In the game, it is not common for a Japanese sub to remain operational after a DC attack. Indeed, they are sunk about 40-50% of the time. At least that has been my experience in my CHS 159 game. This is again related to the accuracy of the attack and to the large number of DCs in the patten employed by allied ships. I have seen instances where a sub has incurred 4-5 DC hits from a single pattern. Not quite historical. U.S. subs have a far better survival rate but this due more to the small damage factor of the Japanese weapons and fewer DCs in the pattern.

On the other hand, the lethality of the weapons themselves actually appear to be understated. Few things upset me more that to see a comment on the combat replay that sub XX has taken a direct hit by a DC and then find that flot damages is only on the order of 30-40. A direct hit should result in the destruction of the sub. Breaching a pressure hull on a submerged sub virtually guarantees its destruction.

We also have the issue of damaged subs foundering on their return to port which increases losses. IRL, few subs were lost in this manner unless as a result of another attack. To have a sub founder 3-4 days after an attack is ahistorical. I can not think of a single Pacific area sub that did. Not to say it didn't or couldn't happen, but I know of no case where this was true.

Most of the time it is Allied players that complain of high sub losses. This is not a JFB vs AFB thing. We overlook that Japanese players tend to incorporate histories lessons into ASW tactics. That is they assign large numbers of search planes and employ H/K groups to prosecute detected subs. Some people call this gamey, some just call it ahistorical. I agree with the latter but then the game itself becomes ahistorical the moment the first turn is run.

So, no. I don't think there is an issue with the sub model itself. I think the main issue lies in the high accuracy of the attack.

A bit rambling I know but I have to leave for work.

Chez

[Historiker]

ORIGINAL: el cid again

Using time as the basis for cost means that gigantic submarine aircraft carriers cost less than many lesser vessels - since they were built fast.

Using displacement as the basis for cost is similar to all other ships - but then the game costs get excessive. We would have 18 for 180 days in the example above - instead of 8 for 80 days. The composite system results in lower cost impacts while preserving relative differences between classes.

Yet another factor might be that sub transports designed as such - simple vessels - cost half what a regular attack sub costs.

Opinons requested.

I already explained it once...


Durability is in witp:
1. Survivability
2. Building costs
3. Active Building time (the time you have to pay for them)

Lets take a CL with a durability of 30. In which ratio you split it is your choice, but just to show you how to calculate:
As 1 is irrelevant because the survivability is given with the first update, the 40 are divided into bowth 15 for 2. and 15 for 3.

Building costs are:
2a Workers needed
2b Material needed
2c Length of the slipway or drydock needed

Ok, now you take Sub XY and compare it with the CL:
2a: 50% needed
2b: 25% needed
2c: 75% needed
3: 60% needed

Now simply adding the numbers and you have the needed durability for the SS.

2,5(2a)+1,25(2b)+3,75(2c)+9 = 16
In this case, the subs needs to have a building durability of 16. AFAIK, building time in witp is 4 times the durability (so 16 means 64 and 30-120 days to pay), so this has to be mentioned as well, but on this basis, you may calculate the building durability.

Moreover; foreign subs mustn't have a greater building durability than 1 as they aren't produced in Japan's shipyards, so Japan doesn't have to pay for them!

[Nikademus]

ORIGINAL: Historiker

I already explained it once...


Durability is in witp:
1. Survivability
2. Building costs
3. Active Building time (the time you have to pay for them)

don't forget;

4) repair

[herwin]

Submarines should not be easy to sink--they're about as robust a seagoing vessel as is built--what other kind of ship can stand the water pressure 100 meters down? Experience was that a depth charge had to be no more than about 8 meters from a sub when it exploded to do significant damage. Operational results also indicated that once a sub had dived to about 30 meters, it was extremely hard to kill.

Bombing accuracy in the game is also excessive. Experience with level bombing was that an average of 3% of the bombs dropped on ships at sea hit. One in nine airborne torpedoes hit--the Japanese experts got two in nine early in the war. Two in nine bombs dropped by dive bombers hit on the average. Allowing the experts to double their percentage (and doing the same thing for ships in harbour) still doesn't produce hit rates like those seen in the game.

[ChezDaJez]

ORIGINAL: herwin

Submarines should not be easy to sink--they're about as robust a seagoing vessel as is built--what other kind of ship can stand the water pressure 100 meters down? Experience was that a depth charge had to be no more than about 8 meters from a sub when it exploded to do significant damage. Operational results also indicated that once a sub had dived to about 30 meters, it was extremely hard to kill.

Bombing accuracy in the game is also excessive. Experience with level bombing was that an average of 3% of the bombs dropped on ships at sea hit. One in nine airborne torpedoes hit--the Japanese experts got two in nine early in the war. Two in nine bombs dropped by dive bombers hit on the average. Allowing the experts to double their percentage (and doing the same thing for ships in harbour) still doesn't produce hit rates like those seen in the game.

Submarines may have been "robustly" built but that robustness had its limitations. A submarine operating at or near maximum depth is vulnerable, very vulnerable to even the slighest damage to her hull. And as the hull would already be stressed nearly to the breaking point from water pressure, an exploding depth charge's pressure wave could easily cause a fatal breech if close enough. And it doesn't have to be a large rupture. The failure of a 1" pipe at 400' is enough to seal the fate of most WWII subs. The flooding would be catastrophic and impossible to stop. Even if confined to a single compartment, returning to the surface would be no sure thing. And forget about blowing tanks in most cases. Even if the ballast tanks themselves aren't ruptured, most subs had little reserve buoyancy with ballast tanks full of air. The weight of a flooded compartment could easily override that reserve buoyancy.

The amount of damage a depth charge will do is directly proportional to the depth of the DC, the explosive power of the DC and the depth of the submarine. A depth charge exploding 8 meters from a hull would be fatal when that submarine is at periscope depth. At 400' a depth charge need not be nearly that close. A distance of 10-15 meters would be sufficient, especially if the boat were a pre-Balao class boat that used only medium tensile strength steel. And most Japanese boats were not nearly as robustly built as US boats.

But still, you seem to have missed the point. The point of my posting is that DC attacks are too accurate in WitP. The number of subs lost in the game has little to do with sub durability but does have everything to do with the number of hits achieved. And this is directly related to the accuracy of the attack.

And as you seem to feel the same way as I regarding bombs, then I assume you also feel the same way about DCs. DC patterns seem to use a similar method for determing hits as is used for bombs. That is each weapon's chance to hit is calculated individually. I believe the chance to hit for both bombs and DCs should be calculated by the pattern, not by the individual weapon.

Chez

[herwin]

ORIGINAL: ChezDaJez
...

But still, you seem to have missed the point. The point of my posting is that DC attacks are too accurate in WitP. The number of subs lost in the game has little to do with sub durability but does have everything to do with the number of hits achieved. And this is directly related to the accuracy of the attack.

And as you seem to feel the same way as I regarding bombs, then I assume you also feel the same way about DCs. DC patterns seem to use a similar method for determing hits as is used for bombs. That is each weapon's chance to hit is calculated individually. I believe the chance to hit for both bombs and DCs should be calculated by the pattern, not by the individual weapon.

Chez
And as you seem to feel the same way regarding bobms, then you must also feel the same way about DCs.

I agree, DC attacks are too accurate in the game. (In reality, it took about 1000 charges per German sub sunk.) Morse and Kimball, Methods of Operations Research, discusses the stats. The other half of the problem until 1943, was that killing a sub was a three-dimensional problem-DCs were fused to explode at a specific depth, and a fuse depth greater than about 8-10 meters was too deep for subs beginning to dive--the one's you had the best chance of sinking. Going from a fuse depth of 8 meters to 16 meters reduced your probability of kill by a factor of three, and if the sub had submerged more than 30 seconds before the attack, your pK was basically zero.

For proximity-fused DCs, the attack error was circularly normal with a standard deviation in each direction of about 100 meters, and the lethal area of a sub was about 1000 square meters. Working it all out, a 1944 DD had to lay a pattern of 13 proximity-fused DCs to get a 14% chance of sinking a sub at a known location. You can see why an average of 1000 proximity-fused DCs were expended per German sub sunk. It was several times worse earlier in the war.