Effective Submarine Use

[piratefish]

I could use some advice regarding effective use of submarines for convoy raiding.

Playing as Germany using Improved 1936. Been building submarines with spotters (6 at a time) and am attempting to cripple the UK economically by targeting her merchant fleet. However, I am meeting with (very) limited success. So far, I have managed to sink a single convoy ship, but it has cost me 3 submarines with spotter attachments. It's currently October 1939 and so far I only have 2 wolf packs of 6 brigaded submarines each out hunting in two separate sea zones in the Atlantic. They have been on assignment since war broke out on 30 August, 1939 with the (very) limited results I just described. I am currently in the process of building 60 subs (6 at a time, each with spotter attachments). At this rate, I will accomplish nothing but catastrophic losses to my submarine fleet and mostly wasted IC. I could really use some help on using effective submarine strategy focused on destroying the allied merchant fleet.

Does anyone have any pointers for strategy, such as the best way to deploy submarines, use spotter planes or not, fleet and pack sizes, mission lengths, best hunting zones, tactics, etc.? I've heard a lot of great things about the results submarines can produce against merchant shipping, but have yet been able to recreate any of that storied success myself. Any advice is appreciated!

 

[Commander666]

Are you current in your techs? Achieving 1940 Wolf Pack early is rather important.

Best hunting is Celtic Sea Area (excluding Bay of Biscay Region). I mission only as to Region. Later, when there are more wolf packs, going further west and south OK too... but not past The Azores or Cap Verde Islands to reduce return voyage of damaged subs. If anything more than 1% damage, get it to port asap.

I personally don't like the rediculous spotter planes on U-boats and my wolfpacks work well without them and have less visibility too. Reducing wolfpacks to only 3 flotilla each is sensible when you have low sub numbers to get more leaders trained, greater coverage, and safer operating in the early years. Over time wolfpack sizes should increase to maintain ability to defeat AI built Allied fleets.

Building a few heavy subs is great for the Donitz aficionado and provide for effective lone hunters at interesting ranges.

 

[piratefish]

Thanks! As of October '39 I am still researching Commerce Raider doctrine. Hopefully I'll see an improvement when that tech is implemented in a couple of months, and then it's full bore toward Wolf Pack doctrine.

 

[Pang Bingxun]

One approach that i did not test but seems sensible is to have only small fleets of up to 3 submarine flottitas. The greatest asset of subs is their low visibilty. Greater fleets habe a greater total visibility and are more prone to be attacked. You donnot want this.

There are 15 sea zones directly adjacent to the british mainland. Having one fleet in each of those zones hunting from dusk till dawn should maximize the ability of subs at night. During day time your sub may better off hiding unless spefic circumstances warrant otherwise.

Also it might be relevant that at midnight production occurs and convoys are reset to accommodate. Keep this in mind. It makes little sense to hunt while no convoys are there to be hunted.

There is a sea reconnaissance espionage mission that can give you information about the position of fleets and convoys. For optimal success you should probably use it.

Also there is the "naval intelligence specialist" intelligence ministers. Germany however only has Hans-Georg von Friedeburg starting in 1942. That might be a little late, but once it comes available it grants a 200% bonus on detecting convoys. Lacking that dismal enigma like Canaris seems the best choice.

 

[Zardnaar]

The way I do it is spam a mix of the level III (Type VII) and level 4 subs (type IX)

The 6 zones that are key IMHO are.

Western Approaches
North Atlantic
Azores
Coast of Portugal
Cape Finestre
Faeroe Gap

Put a wolf pac of 6 subs in each of them. Build 6 or 12 subs at a time reducing the numbers once you get to many to use effectively. By 2 many I mean once you have 36 subs at sea all the time with several flotillas in reserve.

I use them mostly for crew training as well and click that hunt at night button. I put superior tacticians on my subs and in effect use them as suicide subs as when they get intercepted by the allies they rack up that xp and Bohm, Marschall etc end up at level 6 very fast. They end up getting promoted to vice admiral or admiral fairly fast once I have a 6 BC/6 DD/CL fleet ready or an admiral for the 6 BC+2 CVL+10 DD SAG fleets.

Rush your naval techs as well along with encryption. Germany can get their naval tree finished fairly early. Team Donitz and Raeder obviously.

Don't forget Germany can also sink a lot of convoys with surface ships. X3 destroyers and X3 heavy cruisers are not to bad at this and I build BCs over other capital ship types.

Eventually all the subs can be used to invade the USA/UK.

Basically drown the allies in quantity. X12 subs, X12 BCs, X12 DD;'s being built at once until you have enough. These builds are for after the UUSR is defeated.

A balls deep German naval build can start in 1936 and you can have 12 BBs or 18 BCs ready in 1940. Your army will be a bit weak in this scenario.

Or you can build X6 SS in 1936 and rush the level IV subs and build a few as well. You can easily have a copious amount of suns by 1940. You need naval bases in France to us them the best so building 2 lines of them and putting them in Bordeux and the adjacent province can accelerate your sub repair times.

 

[Commander666]

...click that hunt at night button.

I recommend letting the U-boats hunt day and night... or you probably losing out on many convoy hits. While I am comparing using record of what my USA subs are doing in 1956, I don't think it would be different for German U-boats in 1939. Anyway, turns out that slightly over half my convoy sinkings are at day time; and that is using a large sample as I got 5 sub stacks all getting hits nearly every day... and I recorded their activity for about 2 weeks.

 

[Zardnaar]

I recommend letting the U-boats hunt day and night... or you probably losing out on many convoy hits. While I am comparing using record of what my USA subs are doing in 1956, I don't think it would be different for German U-boats in 1939. Anyway, turns out that slightly over half my convoy sinkings are at day time; and that is using a large sample as I got 5 sub stacks all getting hits nearly every day... and I recorded their activity for about 2 weeks.

I think its more for avoiding enemey fleets but I am not sure if it actually works. Subs are so cheap I normally just suicide them now.

1.6 IC for the type VII, 3 lines in 1936 gives you a lot of subs in 1939.

1956 the war should be over win or lose. Late game sub doctrines and the 1945 model are a bit nastier.

I'm goin to trial out a German sub and cruiser focused game soon. I am discovering the hard way the changes made from vanilla HoI2, AoD seems simple though just build carriers swapping naval doctrines as Germany. Get Japan into the Axis and use Manstein to research carrier doctrines.

12 CVs as the USA can destroy the entire IJN., the battle cruisers do not work in AoD as well as HoI2.

 

[Commander666]

I haven't tested day versus night on U-boats getting killed. But I have now thoroughly tested how they get kills at day versus night. I just want to make sure that any impression that U-boats don't get as many convoys during day as at night - or convoys don't run during the day so preventing getting kills - is quite wrong.

This time I did a month of precise recording that noted date, enemy country attacked, number of convoys/escorts gotten, sea zone where action occurred, who was my attacking stack and its total convoy attack value, and whether action occurred day or night using the mini-map. In the month of June 1956 there were 32 encounters with enemy German and Japanese convoys.... ... ... 19 occurred during daytime. The biggest convoy kills all were during the day. In total 33 convoys were sunk during the day; and 22 during the night.

So. while convoys might only be running when the clock hits midnight- if hunting in different oceans some places will be day and other night at that time. However, there is no pattern what-so-ever that I can see that relates to the clock and midnight. In fact, I actually think convoys run in packets along the route, and not just at midnight. In both the Atlantic and the Pacific I was getting hits both at day and at night locally- so shedding doubt on any relationship to the game registering its convoys as occurs at midnight. I much more see a pattern of any convoy route can get a hit anywhere along its length at anytime - be it day or night at that particular spot when the action occurs.

Yes German CTFs without doctrine change are so much dead meat. My considerably smaller American CTF completely trashed a huge German CTF that had more of everything including a CV-10 when I only had CV-3s (which was also the majority of the German CVs but they had a couple more). Anyway, my fleet sank ~28 of his ships... and all I got was a BB-4 damaged a bit over hallway. I did have a stack of NAVs helping as I basically can field an air umbrella wherever I am - even if it is 3000 km range STR flying in from Timbuktu.

 

[Zardnaar]

I haven't tested day versus night on U-boats getting killed. But I have now thoroughly tested how they get kills at day versus night. I just want to make sure that any impression that U-boats don't get as many convoys during day as at night - or convoys don't run during the day so preventing getting kills - is quite wrong.

This time I did a month of precise recording that noted date, enemy country attacked, number of convoys/escorts gotten, sea zone where action occurred, who was my attacking stack and its total convoy attack value, and whether action occurred day or night using the mini-map. In the month of June 1956 there were 32 encounters with enemy German and Japanese convoys.... ... ... 19 occurred during daytime. The biggest convoy kills all were during the day. In total 33 convoys were sunk during the day; and 22 during the night.

So. while convoys might only be running when the clock hits midnight- if hunting in different oceans some places will be day and other night at that time. However, there is no pattern what-so-ever that I can see that relates to the clock and midnight. In fact, I actually think convoys run in packets along the route, and not just at midnight. In both the Atlantic and the Pacific I was getting hits both at day and at night locally- so shedding doubt on any relationship to the game registering its convoys as occurs at midnight. I much more see a pattern of any convoy route can get a hit anywhere along its length at anytime - be it day or night at that particular spot when the action occurs.

Yes German CTFs without doctrine change are so much dead meat. My considerably smaller American CTF completely trashed a huge German CTF that had more of everything including a CV-10 when I only had CV-3s (which was also the majority of the German CVs but they had a couple more). Anyway, my fleet sank ~28 of his ships... and all I got was a BB-4 damaged a bit over hallway. I did have a stack of NAVs helping as I basically can field an air umbrella wherever I am - even if it is 3000 km range STR flying in from Timbuktu.

Big fleets used to have a combat penalty so you could use 6 BCs+6 escorts to take on 100+ ships and sink heaps of them.

That trick doesn't seem to work anymore in AoD its all about the carriers. My current German game is using heavy cruisers and subs as an experiment.

 

[Commander666]

1956 the war should be over win or lose.

Just to explain, about every decade or so, I switch to playing the other side that was almost annihilated. So, playing as Germany (it was a German file save sent me in which that guy built a fantastic Wehrmacht) I played up to launching Barbarossa. Then I switched to playing Russia as the defender.

Having put the Wehrmacht on the run, I switched to playing as Japan and puppeted China... and eventually amphibed the British Isles. Meanwhile I let the German and Soviet AIs battle it out. Germany eventually got Bitter Peace.

Then having joined the Axis and my IJN having sunk every remaining allied ship, there remained only Canada and continental USA to conquer. Every other part of the previous Allies was annexed. Well, this was when I switched to playing USA to see if I could prevent the inevitable invasion. Given I had little air force, no ships and few army, it made for a challenging game.

Now 10 years later the USA has retaken the Pacific, liberated the Warlords, India and 20 other puppets including the most useful Arab Federation. And a good sized American force is dug in at the Caucasus. Our many CTFs now rule the oceans and the remaining challenges are liberating the UK, putting another army in at Spain to open the Gibraltar Straits, and probably a 3rd army in Southern Italy as I already have Sicily. With the additional threat of an amphib anywhere on the Atlantic Wall, this should nicely thin out the unbelievably humongous Wehrmacht (357 infantry, 83 armored) as they will be facing 4 fronts.

The action right now is using my remaining 49 wings of B-47s to bomb Japan, Italy and Spain to smithereens while trying to avoid the Lutfwaffe's 117 squadrons of supersonic fighters. Tokyo, Rome and Madrid have all been nuked. But perhaps it is getting close to switching back to Germany to see if I can change the inevitable Armageddon coming their way? Either way, I intend this game to run until 1964.

Late game sub doctrines and the 1945 model are a bit nastier.

The nukes are even nastier!

 

[Pang Bingxun]

I think its more for avoiding enemey fleets

That for one, but it is also about what happens if battle does break out. Night combat modifiers depend on naval doctrines, with the more advanced ones subs get as effective during night as during day, thus possibly eliminating any need to hunt at day. The combat value will be 100% at night while those of surfaces ships, carriers and air plaines will suffer, thus shifting balance greatly in favour of submarines. During day time subs are better off to avoid engagements. Naturally there are exceptions to any rule. Circumstances prevail over principle.

 

[Zardnaar]

Just to explain, about every decade or so, I switch to playing the other side that was almost annihilated. So, playing as Germany (it was a German file save sent me in which that guy built a fantastic Wehrmacht) I played up to launching Barbarossa. Then I switched to playing Russia as the defender.

Having put the Wehrmacht on the run, I switched to playing as Japan and puppeted China... and eventually amphibed the British Isles. Meanwhile I let the German and Soviet AIs battle it out. Germany eventually got Bitter Peace.

Then having joined the Axis and my IJN having sunk every remaining allied ship, there remained only Canada and continental USA to conquer. Every other part of the previous Allies was annexed. Well, this was when I switched to playing USA to see if I could prevent the inevitable invasion. Given I had little air force, no ships and few army, it made for a challenging game.

Now 10 years later the USA has retaken the Pacific, liberated the Warlords, India and 20 other puppets including the most useful Arab Federation. And a good sized American force is dug in at the Caucasus. Our many CTFs now rule the oceans and the remaining challenges are liberating the UK, putting another army in at Spain to open the Gibraltar Straits, and probably a 3rd army in Southern Italy as I already have Sicily. With the additional threat of an amphib anywhere on the Atlantic Wall, this should nicely thin out the unbelievably humongous Wehrmacht (357 infantry, 83 armored) as they will be facing 4 fronts.

The action right now is using my remaining 49 wings of B-47s to bomb Japan, Italy and Spain to smithereens while trying to avoid the Lutfwaffe's 117 squadrons of supersonic fighters. Tokyo, Rome and Madrid have all been nuked. But perhaps it is getting close to switching back to Germany to see if I can change the inevitable Armageddon coming their way? Either way, I intend this game to run until 1964.



The nukes are even nastier!

Fair enough.

Did some testing and here is my current build order.

Jan 1st 1936

X3 SS w/spotters (type VII)
X3 heavy cruisers, fire control, radar etc.
X2 lt cruisers (everything that increases spotting

And rush research on hte level 4 subs, IC whore whats left and build infrastructure- X3 factories, infrstructure on high IC/resource provinces.

Also build X1 synthetic oil and material things.

Build X3 level IV subs and keep the lvl 3 lines running (gearing bonuses).

You can have a fun little pirate game doing this, you can raid Canada, Australia, Ceylon, South Africa etc for resources and bugging out before the allies can respond.

Might be low on resources and the plants can consume huge amounts of energy and oil, hence the raiding.

Downside is army will be a bit weaker. And there are times when IC is diverted away from the navy such as Barbarossa which generally takes a year or so to do (better player maybe can build navy and do barbrossa in 3-6 months?).

 

[Count of Reval]

Some advice (at least for a vanilla game, especially as human Germany against AI UK):

• Keep submarine techs and models up-to-date. They can be rushed, if needed.
• Build enough submarines. According to Dönitz's rule of thumb: 1/3 are on patrol, 1/3 on route, 1/3 in port (being repaired/replenished). Lost units has to be replaced as well. Have some subs in reserve.
• Try to keep the blockade ring closed. Convoys can find the gap.
• Use single unit up to three unit fleets. This mitigates risks. Depending on subs available, it's recommended to have several hunting layers of them. Preferably in two province chains isolating the target country from convoy destinations, and other subs covering sea areas and regions as well.
• Micromanagement is useful. A convoy hunting isn't as effective as possible, if most of the subs leave patrol areas in the same time and clog ports. It helps if you name fleets by assigned hunting destination (if the sub fleet is sunk or damaged, you'll know which area needs a back up).
• Use the naval combat patrol mission, active in night. Naval combat patrol is much-much more effective against convoys. As you are targeting now warships as well, night gives a cover and helps to survive.
• There are some hunting sweet spots. Those provinces are particularly useful when the number of subs is for any reason below some critical level needed for a full blockade. These are Pentland Firth, Southeast Faroes Gap, Rockall Bank, East Celtic Shelf, Channel Approach, Gulf of Morocco (if Axis doesn't control Gibraltar).
• You can hunt warships as well. Assign heavy subs (preferably) to a naval combat patrol mission next to enemy's naval base provinces. Subs will be lost in some point, but before that they can often knock out AI fleets for a period of time helping the convoy hunting indirectly.
• Keep an eye on losses. If you are not sinking anything or take severe losses yourself, there has to be a reason.
• There's a reasonable window of opportunity. As it happened in real history, ASW technology will eventually catch up. In some point the convoy hunting isn't worth the effort anymore.