Some thoughts on commerce raider designs.

Can commerce raiding be cost effective in WWII?


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Ok, so aircraft and radio make surface warship commerce raiding a loosing proposition, but lets still look at the concept, and see what we can come up with. For a time frame, lets say 1919 till 1945, and lets explore the means of delivering weapons fire to merchant shipping around the world, be that in the form of naval gunfire, mines, torpedoes, {other}, or air attack.

For the surface combatants, lets look at both disguised and normal builds, and for submarines, lets see if we cannot come up with more than just mines and torpedoes from submerged positions, and naval gunfire while surfaced.

For the air attack aspects, lets look at what they need for weapons, and then figure out what the weapons load needs in the way of a delivery system.

Any thoughts?

EDIT: embarrassing, but how do I add a poll again?

EDIT #2: got the poll up, it is public, and multi choice.
 
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For it to work you would need them to be able to blend in with other shipping and not stick out like a sore thumb before the declaration of war and while on the high seas.

Mining a harbor while a raider was leaving coupled with submarine actions in the vicinity of the harbor would be good. Coordination with subs and aircraft helps while they are loose. Even having the ship sink itself to block a harbor or area of a harbor if they are thought to be found out might work.

I don't know if a aircraft would help but not running on coal but diesel engines to cut down the smoke made would go a long way to helping them.
 
For the Pacific, it's a war winner as OTL handily demonstrates. Japan is an island nation which is overwhelmingly dependent . This also means that the WAllies needs to secure their naval LOCs against interdiction. The WAllies took the threat seriously and hence appropriately invested a portion of their considerable resources in the issue. The Japanese did not take the threat seriously and failed to allocate their exceedingly scarce resources to it. As a result, Japan's merchant fleet was pretty much wiped out over the course of 1943-44 once the problem with American torpedoes was fixed while the Japanese sub fleet had it's time wasted sending meager supplies to isolated garrisons that no longer served any strategic value.

This less of the case in Europe. Germany is overwhelmingly a ground power which lacks both the shipyard capacity and sufficient time to field a large enough submarine fleet to successfully strangle Britain before the US comes in... at which point they lack the means to strangle Britain ever. Meanwhile the Anglo-American blockade constrains Germany's resource intake, but does not outright cripple it. Overwhelmingly, the key to a conventional victory in Europe invariably is going to be in a massive ground war that breaks the enemies armies and carries the war into their homeland. Naval (and air) power invariably become mere auxiliaries to this.
 
A CVL Raider-4 aircraft for spotting and Combat Air Patrol plus guns/torpedoes to take out freighters.

For ASB it could also submerge.

Captain Jack Sparrow in command!!!
 
I think the question is more about commerce raiding surface vessels. Using subs as commerce raiders is a given, the utility depends on how important seaborne commerce is for your enemy. For example if the Cold War ever went hot, and lets exclude nukes just for arguments sake, "commerce raiding" by NATO would be of little use and brief, any WP merchants would be swept away quickly, and the WP did not rely on seaborne trade to the extent cutting it off would be a major problem.

For a maritime power subs, and cruisers would do nicely...cruisers need aviation of some sort and need to be fast. For powers without much of a navy (Germany for example) fast merchants or raiders built from keel up but looking like merchants, equipped to change outline easily, with guns/torpedoes (and helos if possible). Need to be able to run away from most warships, but basically staying away from warships etc.
 
First question is are we talking about a purpose-built warship or more of a merchant raider/auxiliary cruiser design? Obviously the dividing line is fuzzy but there will be general themes for the two.

The second point is that the design is going to depend on the situation the raider is operating in. Subs are the best choice when there's likely to be very significant opposition protecting the merchant ships and OTL demonstrates that submarines can be tremendously effective. However, torpedoes are expensive, large, and subs can only carry a relatively small number of them. Deck guns are effective but much less so in the presence of airpower as subs need to be more careful about exposing themselves on the surface. If you're raiding in an area where you don't really need to worry about air attack then surface ships are the better choice because they can carry more armament and have greater endurance. You'll only need pretty small guns to sink merchant shipping so the size of the guns you fit will be dictated by the opposition the surface ships will need to worry about fighting. You'll want guns heavy enough that the raider can put up a real fight and deal with standard convoy escorts but not too big, like the kind you'd want against a battleship or such, as it's a waste of resources because you're investing in the capability to defeat an enemy you won't encounter much. Plus you should have dedicated warships for combating that sort of enemy. So with all of that in mind I'd say the best armament for an effective raider operating in a zone without significant enemy airpower and where the presence of enemy capital ships is unlikely would be along the lines of a light cruiser or one of the French heavy destroyers but optimized for long range and endurance. 6-inch guns are plenty against merchantmen and ASW escorts and will give it the option to engage if there are enemy cruisers present. 6-inch is also the upper limit on what can be loaded by hand so that simplifies the gun mounts. You can also give it some torpedoes to give it a bit more punch and a better chance if it runs into a superior enemy force. You'll also want it to be as fast as you can make it without sacrificing too much so your raider can at least try to run away from said superior enemy force. This type of warship could also be a decent general purpose ship which is good as it gives you more flexibility and can be produced in large numbers which is always a plus for a commerce raider. However, this is specifically considering a warship designed to operate as a raider under the conditions I outlined above. If those change and enemy airpower is present or there's a strong likelihood that enemy capital ships and heavy cruisers will be present in the area you're hunting merchants that will chnage the optimal design. Subs would probably be best in those situations, honestly. Lastly, if you're looking for a merchant cruiser-type of ship your best bet is probably going to be throwing the heaviest guns you can on a merchant ship you've modified to take the weight and ideally increased the endurance and speed on. That's not a ship you'll use in a war zone. It's job is to cruise around the rest of the world where the regular navies have a minimal presence and hunt down any enemy shipping it finds.

Best,
Jack
 
I'll address this strictly in 21st Century terms.

1. Appearance like any 'normal' cargo ship

2. Extra fuel tanks & one portion of power plant for efficient cruising

3. Ability to surge to high speed for rapid relocation. Dual pwr plant?

4. Able to DL target data from other ships, aircraft, shore agents, satilites, and most important drones/RPV.

5. Primary weapon anti shipping missles, secondary torpedos.

6. Mine laying capability dependant of area of operations/mission

7. Anti aircraft capability.

One or two of these operating within 200nm of a major port would cause severe havoc for a couple days. Alternately a major shipping lane. I'd not expect one to last long, so the maximum number of attacks possible in a congested area.

Alternately a port attack ship with the cargo holds loaded with verticle launch cells. The missiles would be a combination of high capacity war heads for precision strikes, incendiary, and submunition of 1-5 kilo explosive charges.
 
I'll go a long way in agreeing with Obsessed Nuker on the overall most important priorities, but stick to the Navy here.

I'll agree that the most cost-effective approach was probably the converted merchant raider. Have lots of these and the opponent is in a lot of trouble for a while.

Subs obviously, have lots of these and the opponent is in a lot of trouble for a while.

The capital ship raider has a point if there is tankers and supports available

Problem occurs when there start to be enough escorts, merchants get registered worldwide, the send out raiders needs repairs and so forth.

To make the surface raider concept work you need a better access port. If there is a 50% loss going in+out of harbor then its not a long-term sustainable strategy.
Thus, Germanycould benefit tremendously in the Battle of the Atlantic from having Spain/Gibraltar on board.

SO, long term options:
A strong and fast enough raider fleet that it cannot be effectively contained (eg. reducing in-out loss ratio). Not easily achieve (cf. critiques of my current TL).
good long range fighter's and torpedo planes would help quite a bit
Much more effective submarines (eg. electroboote)
Naval air power to match the opponents.
Sustainable off-shore refueling option. That will be large purpose built submarines I guess. Maybe have a few float planes as effective scouts (eg. Japanese submarine floatplane tenders).
Have no-one reading your secret messages (not to be underestimated)
Purpose built subs as mine-layers?
 
It would seldom be a war-winning measure. But it could be, in that time frame, a significant contribution to the war effort, and by no means should it automatically be a losing or break-even proposition.

However, this depends entirely not from the country fielding the commerce raiders, but upon the enemy.

Indeed, if the enemy does not depend significantly from overseas shipments, this is obviously a non-starter.

If the enemy does depend on those, then you probably get my answer: successful but not Earth-shaking.

It still could be a war-winning measure (not historically but in WI scenarios) if the enemy both depends on shipping and fails to protect the sea lanes - as with Japan in WWII.

For the opposite example, the British Empire did depend on shipping in WWII, but the more it depended on that, the more it bolstered its defensive measures, eventually having to recruit significant resources, both of its own and, importantly, of its main ally. Thus commerce raiding against British shipping was successful for some time, but not a war-winner.

Note that much depends on the duration of the war. War on shipping is a long-term proposition. All the Axis powers were betting on a short war. If they had been correct, then the issue would have changed radically.

---

A separate note as to disguised "auxiliary cruisers" (actually armed merchantmen). While they obviously appeal to the cloak-and-dagger side of alternate history fans, they never were more than a modest nuisance. Especially in a long-term perspective, which, as mentioned, is the perspective for commerce raiding.
The good reason to set up such contraptions mainly is when you can't defend your own shipping, thus you have these cargo tubs rusting in your ports. Since they don't serve any purpose, you can just as well use them as throw-aways.
 
Can commerce raiding be successful depends on who the raider is and who the target is

and i disagree (mostly) with the idea that the best raider is a disguised merchant raider

Once a convoy system is in place (and to be honest it should be from day 1) a merchant raider to me loses its appeal
 
How about a British Leander class (WW2 Ajax Achilles of River Platte fame). A good all around fast ship with range and decent firepower for a light cruiser. Can accomplish all sorts of missions besides commerce raiding if necessary. (or a WW1 British town class, i.e. Sydney)

The problem with purpose built raiders is that your country doesn't necessarily know who you are fighting when you are ordering them (If your Germany, maybe Britain ends up neutral and you need to protect your own commerce or blockade a port). Its best to make a decent all around cruiser that can do raiding in a pinch.

As a wartime supplement Be prepared to outfit any merchants laying around quickly (might mean guns, shells and mines stored in colonial ports until war occurs).

If a special design is really necessary, take the basic Leander class, as a quick conversion, remove a couple of rear turrets and add float plane store and some mine racks.
 

hipper

Banned
How about a British Leander class (WW2 Ajax Achilles of River Platte fame). A good all around fast ship with range and decent firepower for a light cruiser. Can accomplish all sorts of missions besides commerce raiding if necessary. (or a WW1 British town class, i.e. Sydney)

The problem with purpose built raiders is that your country doesn't necessarily know who you are fighting when you are ordering them (If your Germany, maybe Britain ends up neutral and you need to protect your own commerce or blockade a port). Its best to make a decent all around cruiser that can do raiding in a pinch.

As a wartime supplement Be prepared to outfit any merchants laying around quickly (might mean guns, shells and mines stored in colonial ports until war occurs).

If a special design is really necessary, take the basic Leander class, as a quick conversion, remove a couple of rear turrets and add float plane store and some mine racks.

Leander had an embarked seaplane without removing any turrets,
However you are quite correct light cruisers with decent range and a decent turn of speed are very good commerce raiders.
 
If you google "commerce raiders of WWII", you end up with a list of German and Japanese merchant raiders which had some success until the success stopped. If you add the Graf Spee, and U-boats, they were also successful until their success ended. The case of the Bismarck goes to illustrate that success isn't a sure thing. I think a successful commerce raider should be on the winning side. But the winning side's commerce raiders are blockade ships. It's semantics.
 
Commerce raiding will always be an option against a nation that depends on overseas traffic and resources. However, for surface raiders, the oceans start getting pretty small by the mid 1940's. The combination of increased numbers of long range aircraft, aircraft carriers, better and faster communications, and convoys makes it harder for surface raiders to "get lost" in the oceans for an extended period.

In most instances, I think surface commerce raiding is mostly valuable as a propaganda tool and way of making a nation redeploy (waste) naval forces that might be more useful in key campaign locations.

By the early/mid 1940's, I'd suggest that the ideal surface raider would be a ship in the CL-CA displacement range (6-10,000 Tons), optimized for high speed, very high endurance, torpedo capability, with a battery of dual purpose anti-arcraft guns no larger than 5 inch, and with the most sophisticated electronic and hydrophonic surveillance technology available. I would get the high speed and endurance by sacrificing all armor and heavy guns: The idea being that the key to success is staying at sea and diverting enemy assets while not getting sunk. Do this and an extended sortie is valuable even if it results in minimal enemy merchant losses. I would also consider equipping the ship with a fairly significant aviation capability (possibly equivalent to the Japanese Tone class cruisers), containing aircraft that would be capable of mounting their own attacks on isolated merchant ships and shooing down enemy aerial scouts. Such a ship would only be useful against an Island nation like Britain, Australia, or Japan, and by the 1940's submarines are really a better and far less costly option.
 
Commerce raiding will always be an option against a nation that depends on overseas traffic and resources. However, for surface raiders, the oceans start getting pretty small by the mid 1940's. The combination of increased numbers of long range aircraft, aircraft carriers, better and faster communications, and convoys makes it harder for surface raiders to "get lost" in the oceans for an extended period.

In most instances, I think surface commerce raiding is mostly valuable as a propaganda tool and way of making a nation redeploy (waste) naval forces that might be more useful in key campaign locations.

By the early/mid 1940's, I'd suggest that the ideal surface raider would be a ship in the CL-CA displacement range (6-10,000 Tons), optimized for high speed, very high endurance, torpedo capability, with a battery of dual purpose anti-arcraft guns no larger than 5 inch, and with the most sophisticated electronic and hydrophonic surveillance technology available. I would get the high speed and endurance by sacrificing all armor and heavy guns: The idea being that the key to success is staying at sea and diverting enemy assets while not getting sunk. Do this and an extended sortie is valuable even if it results in minimal enemy merchant losses. I would also consider equipping the ship with a fairly significant aviation capability (possibly equivalent to the Japanese Tone class cruisers), containing aircraft that would be capable of mounting their own attacks on isolated merchant ships and shooing down enemy aerial scouts. Such a ship would only be useful against an Island nation like Britain, Australia, or Japan, and by the 1940's submarines are really a better and far less costly option.

but surely any convoy with an escort of 3 of more ships of destroyer size would be able to drive off or sink this raider.

and if you make the raider bigger then your escort just needs to be bigger
 

Driftless

Donor
If you google "commerce raiders of WWII", you end up with a list of German and Japanese merchant raiders which had some success until the success stopped. If you add the Graf Spee, and U-boats, they were also successful until their success ended. The case of the Bismarck goes to illustrate that success isn't a sure thing. I think a successful commerce raider should be on the winning side. But the winning side's commerce raiders are blockade ships. It's semantics.

I'd agree as time and technology progressed, the life expectancy of the commerce raider gets shortened up considerably. The combination of aerial reconaissance and radar/sonar made it a lot harder for the raider to hide anywhere. Even potential Somali pirates have drones chasing them today.

Late 19th & early 20th century, the life-expectancy of the raiders should have been somewhat longer. The SMS Emden is the poster child for having far more impact than any light crusier should - in part as it could effectively hide in the Indian Ocean long enough to force the British to really expend some naval resource to find her.

Still, the commerce raider needs to have both a mother ship for restocking supplies and a secure place for that exchange to occur. Also, a secure location for completing minor repairs and basic maintenance. You need both ESP & some luck to have those peices work for you over time.
 
A commerce raider needs long endurance, a light logistical footprint - it should be able to refuel and restore from prizes - be able to fight off minor escorts and be able to run from major escorts. In addition, it also needs to be useful as a fleet unit - specialist single-role ships are a poor use of resources. In effect, that means it should be a light cruiser.

One point, sometimes missed, is that the force pursuing a guerre de course needs to tie down the enemy's heavy forces. Otherwise, they're free to unleash maximum effort on hunting down the raiders. That means the light cruisers need to be backed up by a battle fleet large enough to prevent a major surface escort being attached to convoys.
 

trurle

Banned
I agree what commerce raiders were progressively vulnerable toward the 1945.

But the most formidable ship with commerce raider capabilities may be the Japanese I-400-class submarine.
Why?
1) 20000km range (attacks anywhere)
2) Submarine with air-search radar (very difficult to ambush - none lost in actual war)
3) 3 carried seaplanes, each 1200km range, 4 hours endurance and each carrying a torpedo. Can detect a convoy in 400 km wide circle.

The results of attack (purely fictional) may be the following
The weather assumed to be calm.

7:00am : scout plane detected Canadian convoy of 2 Flower-class corvettes and 8 supply ships, at range 150km, aiming point 100km, sailing at 16kn (29.6km/h). The scout plane went undetected visually or by Type 271 radar at range of 50km. Also, scout medium-gain antenna did allowed it to send a message to sub without being intercepted. The small size of convoy is because the area is considered low-risk (8000 km from Japanese bases)
7:05 Sub started to move to intercept point after receiving a radio message, speed is 18.7kn (34.6 km/h)
7:40am : arrival of scout seaplanes to sub, raising to deck started
8:10am : all seaplanes on deck, refuelling and arming with torpedo started
10:55 : sub arrived to intercept point after travelling 112 km. Distance to convoy 52km.
11:00 : 3 seaplanes in attack configuration launched undetected and went to loiter area. Distance to the convoy 49.5km. Submarine submerges.
12:40 : The convoy passing 4km from submarine. 8 "Long lance" torpedoes are launched. The aircraft advance from loiter area 60km away.
12:43 : Torpedoes strike. 1 corvette and 1 supply ship destroyed. 2nd Canadian corvette charges to sub to use his "Hedgehog" projector. Call for help to nearest friendly patrol bomber (1000 km)
12:48 : 3 torpedo launched from aircraft. Corvette-sub distance 3km. Corvette damaged (aerial torpedo are not powerful enough to sink it immediately) and stay dead in water.
12:50 : Supply ships of convoy receive orders to scatter.
13:25 : The sub is out of artillery range of damaged corvette. Distance to closest supply ship 13 km - out of range of their 4-inch guns. Submarine surfaces.
13:50 : After 12 hits by 140mm HE shells (out of 100 shots) the 2000-ton supply ship visibly sinking. The range to closest intact supply ship 31km, distance to damaged corvette 22 km
14:05 14 km from sub to damaged corvette. Sub started to fire 140mm gun.
14:15 After receiving further 25 hits (out of 50 shots) corvette sinks. Seaplanes are recalled.
14:21 Seaplanes are ditched. Have started to raise them on deck
15:01 : Sub radar have detected incoming US patrol bomber at range 80 km. 3rd seaplane is still on the deck outside of hangar, folding wings in hurry.
15:06 : Closing deck hangar, submerging.
15:13 : US patrol bomber arrives. Submarine is up to 1.8km from last-seen position, on the 100m depth. Visual detection failed. Chances for fatal hit by one of the randomly dropped 36 depth charges in 11km2 search area are 0.83%.

Summary: Canadian loss 4 hulls, 6000 ton displacement.
Japanese loss, averaged for long-term - 55 tons.

Long term results: Allied forces convert more heavy transports to auxiliary carriers to detect a predating I-400 submarines before they strike. Also, convoys become larger and less frequent even in remote areas. Eventually, I-400 efficiency comes to nil, but the cargo carrying capacity of allied fleet is reduced by half due the security measures.
 

Redbeard

Banned
Of course commerce raiding can be war winning, that is how you most cost effectively break island nations like UK or Japan.

It came close vs. UK in WWI (and perhaps in WWII) and it did the job vs. Japan. The bombs just delivered a merciful coup d'grace.
 
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