Most effective "possible" WWII weapon at sinking merchantmen?

Based upon another thread, I have this question.

In an ATL Non-Nazi Germany, that starts off in 1919 planing a 'revenge war' with the UK as Enemy #1, and France as Enemy #2, what could athey do differently/better to prepare for such a war?

So, my proposal is:

Germany builds something like the USA's B-25 or B-26 medium bombers, but designed as a land based naval aviation 'ship hunter'.


Below are links and excerps to the B25 and B26 bombers

B25:
http://en.wikipedia.org/wiki/B-25_Mitchell#Specifications_.28B-25H.29



General characteristics
Performance
Armament

  • Guns: 12–18 × .50 in (12.7 mm) machine guns and 1 75 mm cannon
  • Bombs: 3,000 lb (1,360 kg) bombs
B26:
http://en.wikipedia.org/wiki/Martin_B-26_Marauder#Specifications_.28B-26G.29



General characteristics
Performance
Armament

Source material from previous thread:
From Navweps Bofors 40 mm/60 (1.57") Model 1936 used a [FONT=Arial,Helvetica]1.960 lbs. (0.889 kg) AP M81A1 shell (so no to 5lb) that goes through [/FONT][FONT=Arial,Helvetica]1.20" (30 mm)[/FONT] at [FONT=Arial,Helvetica]2,000 yards (1,829 m)(and at 0 yards you get [/FONT][FONT=Arial,Helvetica][FONT=Arial,Helvetica]2.70" (69 mm)) but you do get 2 per second (if you can keep it feed) [/FONT][/FONT]

Apart from the fact that the ships are to the west of the UK and you have to fly from the east (so only a few very large Condors can really do it) and the merchant ships are not unarmed they have gun on them .5/20mm/3'/4' all later than on warships but still you are a fragile target compared to a ship and a long way from home are you really going to walk .5 fire onto a ship with its own .5s (and bigger stuff)... (I'm also not sure that 30x40mm hits will sink most merchant ships (unless you hit the right parts most of yours will hit the top and grouped together from each burst)


-But any big aircraft will be expensive (range and load are not cheap)

-But the German navy isn't allowed that many aircraft (aircraft are for the Luftwaffe)

-But the Luftwaffe is concentration on supporting the German army ( and without that you don't get bases in France/Norway and you need much bigger aircraft)

- The British have a lot of ships (just to make it harder for you)

- if you get down to 1000 yards (to hit accurately) then the ships will get some hits (and aircraft can take a lot less than ships).

- Turrets make you deal with deflection shooting, nobody was good at deflection shooting unless they are very good (1% of pilots) or they had late war giro gun sights (1944+)

- OTL turrets guns don't have a good history, they are much heaver than fixed weapons and spoil the aircraft's speed and they miss a lot need more crew and cost much more .....

- Just hitting ships was hard (from a range and speed that was survivable v defensive fire) hitting just under the waterline will be very hard (and to far under the water and shells will slow down to much) I think most hits will be in well above the water line.

Personally I would go with high velocity folding fin rockets (R4M) from fighterbombers but you cant as they are 1944+

I would have them armed with a fully retractable (meaning that on the ground or in flight, except while actually making an attack run, the turret if fully retracted into the 'bombay' and the doors closed) turret mounting twin .50 cal machine guns and twin 40mm autocannons. The twin .50 cal machine guns would be used for strafing the lightest of craft and to 'walk' their fire on target before the twin 40mm autocannons commence firing.
 
Other then torpedos, skip bombing.

Small calibers guns aren't really effective at sinking large ships, they make lots of holes up top, but they don't make large holes to let water in.
 
Big, big problem there - combat radius of a medium bomber is only about 1,000 miles, and you're looking at fighting the UK before France. That means you're trying to hit the Atlantic convoys from bases in Germany.
Unless you plan to fly down the Channel to the Western Approaches in the teeth of fighter command and without the benefit of your own escorts, then you're going to have to do what the Bear bombers did in the Cold War and come down through the Iceland-Faroes gap having flown up the North Sea. That requires an exceptionally long-ranged aircraft, realistically probably one carrying no significant warload given the technology of the time.

The issue the Germans have is that prosecuting a trade war against the British effectively given WW2 technology effectively requires them to have bases in France (Norway helps, but that just forces the British to route the convoys southwards out of the worst of the weather - in OTL a large fraction of the tonnage taken out of action was laid up in the yards awaiting repair after weather damage from heading just south of Greenland in winter!). To get those bases in France requires them to fight and win a war against the French - the resources needed for which are very different from those needed for a subsequent war against the UK.
 
I think overall rockets-even the primitive WWII rockets- were much more effective then heavy guns. Especially as they were easier to install afterwards. A good deal of the battle of the Atlantic was won by lend-lease Grumman Avengers operating from lend-lease escort carriers fitted with rocket rails under the wings.

another weapon used to good success by the German side were the Henschel and Frits-X guided bombs carried by long-range patrol planes (Focke-Wulf 200's) May be in your timeline development of such bombs would start earlier so there would be a ready arsenal of them by 1940?

And while we're at it: May be someone could realize in 1929 that a submarine is supposed to spend MOST of its time under water and that therefore it should be shaped aerodynamically like a plane instead of a ship. With a successful prototype given the right priority, you could have the genuinely marvelous but too-little-too-late type XXI and XXIII type submarines already available at the start of the war.
 
Maybe an ATL pre-emptive Tizzard Mission in the 30s, where the British throw in some Royal Navy design studies on alternate designs for submarine hulls, which allows the Americans to come up with something like the Albacore class much earlier.
 
Based upon another thread, I have this question.

In an ATL Non-Nazi Germany, that starts off in 1919 planing a 'revenge war' with the UK as Enemy #1, and France as Enemy #2, what could athey do differently/better to prepare for such a war?

So, my proposal is:

Germany builds something like the USA's B-25 or B-26 medium bombers, but designed as a land based naval aviation 'ship hunter'.


Below are links and excerps to the B25 and B26 bombers

B25:
http://en.wikipedia.org/wiki/B-25_Mitchell#Specifications_.28B-25H.29



General characteristics
Performance
Armament

  • Guns: 12–18 × .50 in (12.7 mm) machine guns and 1 75 mm cannon
  • Bombs: 3,000 lb (1,360 kg) bombs
B26:
http://en.wikipedia.org/wiki/Martin_B-26_Marauder#Specifications_.28B-26G.29



General characteristics
Performance
Armament

Source material from previous thread:


I would have them armed with a fully retractable (meaning that on the ground or in flight, except while actually making an attack run, the turret if fully retracted into the 'bombay' and the doors closed) turret mounting twin .50 cal machine guns and twin 40mm autocannons. The twin .50 cal machine guns would be used for strafing the lightest of craft and to 'walk' their fire on target before the twin 40mm autocannons commence firing.

Ok...How are they to be employed?

From Germany? Because if your going UK First then you cannot plan on having knocked out France.

So the majority of ops will be conducted within Fighter range of the UK / France

I see a response to long range anti shipping aircraft being developed and deployed being a long range cannon armed fighter interceptor earlier than OTL - something like the Lightning maybe.

I see a better idea being a long rang amphibian aircraft capable of carrying Torpedoes and Bombs and of course being useful for reconnaissance

Keep it simple
 
My fault I guess. This ATL non-nazi Germany is not going to fight the UK and france seperately, nor consecutively, but simutaneously (as per close to OTL). The #1 for the UK is simply do denote the harder to bring down enemy, the main enemy.

So France will fall, then the commerce war upon the UK can begin in earnest.

This strategy is based in part on a few BUA's, or:

Basic
Underlying
Assumtpions

And here they are.

Firstly, IIRC, something like 60% of all tonnage delivered to the UK throughout the war years, was delivered by merchantmen that sailed 'solo' across the atlantic. No escorts, no convoys, no nothing. This was part of the overall strategy of the UK, to scatter widely the independant unescorted ships, so as to reduce the German interest in them, as not only would the U boats have to sail more to take on a second ship, but if the first victim manages to get off a radio message, nearby ships are turning away, thus making the already slim pickings even less attractive, while at the same time offering up a 'target rich enviroment' in the form of the escorted convoys, which gave the UK the chance to mass their escorts as much as possible to put as big a dent in the U boat forces as possibile.

Why didn't the UK simply put all merchantmen in convoys? Overcrowding of her ports once a convoy came in, and an empty port between.

Secondly, any TL Germany that tries to build up a U boat fleet to the point that it is a serious threat to the UK merchant fleet, is also going to have a UK that is building up their combined ASW forces, and like any naval race between the two, the build rate will not favor Germany. As it is impossible to build hundreds of submarines without their being noticed by the allied spies in Germanys shipyards, or within sight of their shipyards, and given the time it takes to build a submarine...
 
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Firstly, IIRC, something like 60% of all tonnage delivered to the UK throughout the war years, was delivered by merchantmen that sailed 'solo' across the atlantic. No escorts, no convoys, no nothing. This was part of the overall strategy of the UK, to scatter widely the independant unescorted ships, so as to reduce the German interest in them, as not only would the U boats have to sail more to take on a second ship, but if the first victim manages to get off a radio message, nearby ships are turning away, thus making the already slim pickings even less attractive, while at the same time offering up a 'target rich enviroment' in the form of the escorted convoys, which gave the UK the chance to mass their escorts as much as possible to put as big a dent in the U boat forces as possibile.

That simply isn't the case. Yes, in the first part of the war convoys were dispersed mid-Atlantic, after they were considered out of effective U-boat range. Once this range increased, ships were escorted all the way.

Yes, there were always ships going around on their own. These were either fast ships (who statistically had a better chance than in a slow convoy), or stragglers. There were a lot of stragglers. Whether or not they made an effort to collect them depended on the risk and the direction - a straggler heading for NA had a much better chance. The weather also had an effect.

But your assertion that 60% of ships sailed independently across the Atlantic is simply wrong.
 
Ignoring for a moment the issue of how you get past France, an attack plane isn't a very good way of taking out a big merchant ship.

A low velocity 75mm gun isn't terribly damaging to a large ship - it can damage it, but disable or sink? Not unless they get VERY lucky.

Its a poor use of resources - the bigger, slower medium bombers are relatively easy to hit at those sort of ranges, and damage tends to mean they don't get home. Its often not realised just how much AA some merchant ships were carrying.

The best weapon the planes could use would be the torpedo, in terms of ships sunk per attack.
 
But your assertion that 60% of ships sailed independently across the Atlantic is simply wrong.
I do not recall which book I read on the subject, that stated clearly that the unescorted made up 60% of the tonnage delivered to the UK during the war, but even then, I have since learned that not all things I read were actually true. OTOH, can you give a factual guess on what percent of the ships did go-it-alone? We know the UK could not have had all the ships in convoys, as they could not have keep up with having for to many ships to unload, with the rest having to wait their turn, and the first ones then being kept in port till an outbound convoy was ready would have been a huge reduction in efficiency, a wartime reduction they could ill afford, right?

I should have taken the time to write out a fully descritpive post in the OP, but I recently had my C drive go haywire on me to the point that I ended up having to swap the C and E drives around, and have been spending totally insane amounts of time with the endless downloads, installing, and restarting of my computer to try to get it fully functional once again, I still have no sound, and my latest efforts were rewarded with no longer having an audio device being detected on my computer, despite the dang thing being reported as "This device is working properly".

That being said, the idea with the references to the american bombers above was to stop floks from claiming that a plane couldn't mount as heavy an armament as I am proposing, IE, the B-25's twelve to eighteen .50 cal machineguns and one 75mm cannon. What I am proposing is a single, fully retractable, turret with two .50 cal machineguns, and two 40mm autocannons, which I think everyone will agree is quite a bit lighter than that of the B-25.

Ignoring for a moment the issue of how you get past France, an attack plane isn't a very good way of taking out a big merchant ship.
With a better prepared Germany, it's not an issue. After all, if an all but unprepared Germany can get lucky, why assume my ATL Germany does worse than OTL?

A low velocity 75mm gun isn't terribly damaging to a large ship - it can damage it, but disable or sink? Not unless they get VERY lucky.
Remember you said this...

Its a poor use of resources - the bigger, slower medium bombers are relatively easy to hit at those sort of ranges, and damage tends to mean they don't get home. Its often not realised just how much AA some merchant ships were carrying.
Ok, so one these mighty UK merchantmen, there will exist that most awe inspiring, most feared, and deadliest of all know AA weapons known to man...

"Grampa, with his coke-bottle spectacles, operating his antiquated deck gun, with which he has had no training, heroicly fires it to great effect, once again proving that the kilngons are not the only folks who can score a"

"Lucky shot, Sir"!:cool:

Sorry, I just couldn't resist that.

I think that we will see that a much more pressing problem for these non-existant medium bomber equivilants, is mechanical failures, because these losses will occure, and likely on every day of the caampaign, depending on the numbers being put into the air.

The best weapon the planes could use would be the torpedo, in terms of ships sunk per attack.
Ok, this is on of those statements that assumes that no better way exists (or in this case could exist), than what OTL had to offer.

For me, let us start with the 4,000 lbs bombload of the B-26. The B-26 is listed as carrying a crew of 7, with 12 .50 cal machineguns in addition, and a speed of 216 MPH (we don't really care what the max speed is on a long flight), and a strike radius of say 1,000 miles or so. Lets take these with a grain of salt, but it gives us a decent starting point.

My fictional 'ship hunters' then get 4,000 lbs of payload, and lets take a guestimated 2,000 lbs of that and call it the turret, the guns and cannons, and the lowering mechinism. With the remaining 2,000 lbs, we get 250 (two pound) rounds for each cannon, and then considerably more for the .50 cal machineguns, lets say something like 500 rounds, even though I suspect I would be selling myself way short.

In a typical mission, say you send out a 5 plane sortie, that will attack one at a time, until they expend all their ammo, or the target sinks.

For an attack profile, come in at 1,00 feet, and pass along side at around 1,000 yards distance. Your gunner aims his .50's at the water right next to the ships side (and not the ship itself), and, once he is satisfied that he is 'on target' commences fire with the 40mm autocannons. Say he has a five second period where he can 'pour it into' his hapless target. The autocannons will be assumed to be quite like the OTL bofors 40mm, and thus get 2 rounds off per second, per cannon. This gives our gunner some 20 40mm shells heading for the target ships hull, just below her waterline. Because the gunner gets to 'walk' the .50's into position, his ammo for the cannons is only expended while 'on target' and so is much more accurate than generally. Let us assume (what I believe to be a grossly optimistic apprazil of the situation) that he gets only 1/10th of the cannon rounds into the ships hull beneath the waterline. Using dual purpose armor peircing, and high explosive (again, not unlike the OTL bofors), thus putting 2 40mm penetration holes into the merchantmens hull below the waterline, and lets say of the other 18 that 'miss' about 2/3 of these err on the side of hitting the ship above the waterline and the other 1/3 hit the water to far away.

So, the first pass, by the first aircraft, has put 2 40mm holes into the ships hull below the waterline, and perhaps 12 additional 40mm rounds into the ships from above the waterline, discounting whatever the .50 cal's might achieve. Now the 2nd thru 5th aircraft come in and (at least) do like damage. Thus, by the end of a single pass, we now have 10 40mm explosive shells detonating within the ship, after having penetrated below the waterline, and some 60 additional 40mm explosive shells detonating within the ship after having penetrated above the waterline.
 
The Germans used the most effective weapon for sinking merchant ships. The type VII armed with torpedoes and a 8.8 cm deck gun. More range, more endurance
 

I was actually thinking more along the lines of this.

albacore2.jpg
 
I think overall rockets-even the primitive WWII rockets- were much more effective then heavy guns. Especially as they were easier to install afterwards.
I agree totally and most of your aircraft will be general army/land attack anyway (or you lose the BoF and it doesn't matter)

another weapon used to good success by the German side were the Henschel and Frits-X guided bombs carried by long-range patrol planes (Focke-Wulf 200's) May be in your timeline development of such bombs would start earlier so there would be a ready arsenal of them by 1940?
But what do you give up to pay ofr them and they are VERY expensive ? (and NG rearmement is a zero sum game as it was already fully overstretched OTL)

And while we're at it: May be someone could realize in 1929 that a submarine is supposed to spend MOST of its time under water and that therefore it should be shaped aerodynamically like a plane instead of a ship. With a successful prototype given the right priority, you could have the genuinely marvelous but too-little-too-late type XXI and XXIII type submarines already available at the start of the war.
But WW2/earlier subs did spend most of the time on the surface, just look at what happened to commanders who where too worried about showing periscopes (or even more so attack on surface at night) from pre war exercises, they did not hit anything and got replaced.
(I think you need, hull shape, bigger motors (E), bigger (better) batteries, better control surfaces/systems (to run at faster speed at a controlled depth), snorkel (+faster charging) and better hydrophones/sonar/asdic (so you can find/target underwater) getting all of this (to work) per war is ASB IMO.
 

hipper

Banned
I do not recall which book I read on the subject, that stated clearly that the unescorted made up 60% of the tonnage delivered to the UK during the war, but even then, I have since learned that not all things I read were actually true. OTOH, can you give a factual guess on what percent of the ships did go-it-alone? We know the UK could not have had all the ships in convoys, as they could not have keep up with having for to many ships to unload, with the rest having to wait their turn, and the first ones then being kept in port till an outbound convoy was ready would have been a huge reduction in efficiency, a wartime reduction they could ill afford, right

You are entirely correct that the introduction of Convoy due to delays in offloading and waiting for ships to assemble represent age a huge reduction of efficiency, I've read that it was about a one third drop.

However the loss of a ship represents a huge loss of capacity, as it will make no further voyages. so the introduction of convoy was regarded as a necessary evil.

As to the percentage of merchant ships traveling in convoy compared to independently routed ships, it varied by year and location.


However Independently routed ships had to have a speed of 13 knots raised to 15 knots in mid 1941, the majority of merchantmen had speeds below 12 knots, so the figure of 60 per cent of goods coming in on independent ships cannot be true.

during May 1942 in the North Atlantic there were only 28 independently routed ships, ( Dan van der vat the Atlantic Campaign) compared to many hundreds in convoy.


Ps there is some academic work on the most effective anti shipping weapons against merchantmen, using data from Malta - it's the torpedo carrying aircraft.






I
I should have taken the time to write out a fully descritpive post in the OP, but I recently had my C drive go haywire on me to the point that I ended up having to swap the C and E drives around, and have been spending totally insane amounts of time with the endless downloads, installing, and restarting of my computer to try to get it fully functional once again, I still have no sound, and my latest efforts were rewarded with no longer having an audio device being detected on my computer, despite the dang thing being reported as "This device is working properly".

That being said, the idea with the references to the american bombers above was to stop floks from claiming that a plane couldn't mount as heavy an armament as I am proposing, IE, the B-25's twelve to eighteen .50 cal machineguns and one 75mm cannon. What I am proposing is a single, fully retractable, turret with two .50 cal machineguns, and two 40mm autocannons, which I think everyone will agree is quite a bit lighter than that of the B-25.


With a better prepared Germany, it's not an issue. After all, if an all but unprepared Germany can get lucky, why assume my ATL Germany does worse than OTL?


Remember you said this...


Ok, so one these mighty UK merchantmen, there will exist that most awe inspiring, most feared, and deadliest of all know AA weapons known to man...

"Grampa, with his coke-bottle spectacles, operating his antiquated deck gun, with which he has had no training, heroicly fires it to great effect, once again proving that the kilngons are not the only folks who can score a"

"Lucky shot, Sir"!:cool:

Sorry, I just couldn't resist that.

I think that we will see that a much more pressing problem for these non-existant medium bomber equivilants, is mechanical failures, because these losses will occure, and likely on every day of the caampaign, depending on the numbers being put into the air.


Ok, this is on of those statements that assumes that no better way exists (or in this case could exist), than what OTL had to offer.

For me, let us start with the 4,000 lbs bombload of the B-26. The B-26 is listed as carrying a crew of 7, with 12 .50 cal machineguns in addition, and a speed of 216 MPH (we don't really care what the max speed is on a long flight), and a strike radius of say 1,000 miles or so. Lets take these with a grain of salt, but it gives us a decent starting point.

My fictional 'ship hunters' then get 4,000 lbs of payload, and lets take a guestimated 2,000 lbs of that and call it the turret, the guns and cannons, and the lowering mechinism. With the remaining 2,000 lbs, we get 250 (two pound) rounds for each cannon, and then considerably more for the .50 cal machineguns, lets say something like 500 rounds, even though I suspect I would be selling myself way short.

In a typical mission, say you send out a 5 plane sortie, that will attack one at a time, until they expend all their ammo, or the target sinks.

For an attack profile, come in at 1,00 feet, and pass along side at around 1,000 yards distance. Your gunner aims his .50's at the water right next to the ships side (and not the ship itself), and, once he is satisfied that he is 'on target' commences fire with the 40mm autocannons. Say he has a five second period where he can 'pour it into' his hapless target. The autocannons will be assumed to be quite like the OTL bofors 40mm, and thus get 2 rounds off per second, per cannon. This gives our gunner some 20 40mm shells heading for the target ships hull, just below her waterline. Because the gunner gets to 'walk' the .50's into position, his ammo for the cannons is only expended while 'on target' and so is much more accurate than generally. Let us assume (what I believe to be a grossly optimistic apprazil of the situation) that he gets only 1/10th of the cannon rounds into the ships hull beneath the waterline. Using dual purpose armor peircing, and high explosive (again, not unlike the OTL bofors), thus putting 2 40mm penetration holes into the merchantmens hull below the waterline, and lets say of the other 18 that 'miss' about 2/3 of these err on the side of hitting the ship above the waterline and the other 1/3 hit the water to far away.

So, the first pass, by the first aircraft, has put 2 40mm holes into the ships hull below the waterline, and perhaps 12 additional 40mm rounds into the ships from above the waterline, discounting whatever the .50 cal's might achieve. Now the 2nd thru 5th aircraft come in and (at least) do like damage. Thus, by the end of a single pass, we now have 10 40mm explosive shells detonating within the ship, after having penetrated below the waterline, and some 60 additional 40mm explosive shells detonating within the ship after having penetrated above the waterline.


in reality the 20 mm cannon used at first by defensively armed Merchantmen, enabled them to stop low level attacks by long range German aircraft While 40 mm bofors guns put a crimp in medium level attacks.

However historically the anti aircraft potential of convoy escorts were enough to inflict unsustainable losses on German naval air missions and fighter protection from escort carriers renderedlong range anti shipping sorties in the Atlantic ineffective.

Regards Hipper
 
I do not recall which book I read on the subject, that stated clearly that the unescorted made up 60% of the tonnage delivered to the UK during the war, but even then, I have since learned that not all things I read were actually true. OTOH, can you give a factual guess on what percent of the ships did go-it-alone? We know the UK could not have had all the ships in convoys, as they could not have keep up with having for to many ships to unload, with the rest having to wait their turn, and the first ones then being kept in port till an outbound convoy was ready would have been a huge reduction in efficiency, a wartime reduction they could ill afford, right?

I should have taken the time to write out a fully descritpive post in the OP, but I recently had my C drive go haywire on me to the point that I ended up having to swap the C and E drives around, and have been spending totally insane amounts of time with the endless downloads, installing, and restarting of my computer to try to get it fully functional once again, I still have no sound, and my latest efforts were rewarded with no longer having an audio device being detected on my computer, despite the dang thing being reported as "This device is working properly".

That being said, the idea with the references to the american bombers above was to stop floks from claiming that a plane couldn't mount as heavy an armament as I am proposing, IE, the B-25's twelve to eighteen .50 cal machineguns and one 75mm cannon. What I am proposing is a single, fully retractable, turret with two .50 cal machineguns, and two 40mm autocannons, which I think everyone will agree is quite a bit lighter than that of the B-25.


With a better prepared Germany, it's not an issue. After all, if an all but unprepared Germany can get lucky, why assume my ATL Germany does worse than OTL?


Remember you said this...


Ok, so one these mighty UK merchantmen, there will exist that most awe inspiring, most feared, and deadliest of all know AA weapons known to man...

"Grampa, with his coke-bottle spectacles, operating his antiquated deck gun, with which he has had no training, heroicly fires it to great effect, once again proving that the kilngons are not the only folks who can score a"

"Lucky shot, Sir"!:cool:

Sorry, I just couldn't resist that.

I think that we will see that a much more pressing problem for these non-existant medium bomber equivilants, is mechanical failures, because these losses will occure, and likely on every day of the caampaign, depending on the numbers being put into the air.


Ok, this is on of those statements that assumes that no better way exists (or in this case could exist), than what OTL had to offer.

For me, let us start with the 4,000 lbs bombload of the B-26. The B-26 is listed as carrying a crew of 7, with 12 .50 cal machineguns in addition, and a speed of 216 MPH (we don't really care what the max speed is on a long flight), and a strike radius of say 1,000 miles or so. Lets take these with a grain of salt, but it gives us a decent starting point.

My fictional 'ship hunters' then get 4,000 lbs of payload, and lets take a guestimated 2,000 lbs of that and call it the turret, the guns and cannons, and the lowering mechinism. With the remaining 2,000 lbs, we get 250 (two pound) rounds for each cannon, and then considerably more for the .50 cal machineguns, lets say something like 500 rounds, even though I suspect I would be selling myself way short.

In a typical mission, say you send out a 5 plane sortie, that will attack one at a time, until they expend all their ammo, or the target sinks.

For an attack profile, come in at 1,00 feet, and pass along side at around 1,000 yards distance. Your gunner aims his .50's at the water right next to the ships side (and not the ship itself), and, once he is satisfied that he is 'on target' commences fire with the 40mm autocannons. Say he has a five second period where he can 'pour it into' his hapless target. The autocannons will be assumed to be quite like the OTL bofors 40mm, and thus get 2 rounds off per second, per cannon. This gives our gunner some 20 40mm shells heading for the target ships hull, just below her waterline. Because the gunner gets to 'walk' the .50's into position, his ammo for the cannons is only expended while 'on target' and so is much more accurate than generally. Let us assume (what I believe to be a grossly optimistic apprazil of the situation) that he gets only 1/10th of the cannon rounds into the ships hull beneath the waterline. Using dual purpose armor peircing, and high explosive (again, not unlike the OTL bofors), thus putting 2 40mm penetration holes into the merchantmens hull below the waterline, and lets say of the other 18 that 'miss' about 2/3 of these err on the side of hitting the ship above the waterline and the other 1/3 hit the water to far away.

So, the first pass, by the first aircraft, has put 2 40mm holes into the ships hull below the waterline, and perhaps 12 additional 40mm rounds into the ships from above the waterline, discounting whatever the .50 cal's might achieve. Now the 2nd thru 5th aircraft come in and (at least) do like damage. Thus, by the end of a single pass, we now have 10 40mm explosive shells detonating within the ship, after having penetrated below the waterline, and some 60 additional 40mm explosive shells detonating within the ship after having penetrated above the waterline.

After 1940, probably 90% of Atlantic traffic was escorted. Most of the rest was straggling.

The 60% figure might be for ALL shipping. It wasn't worth escorting ships once they left the NA - a few hot sports were occasionally escorted, often the 'escort was a Merchant Cruiser rather than A/S, the sub threat outside of the NA was low.

There is also the complex issue of are ships sailing together without an actual escort a convoy or not? Happened quite a bit in the Indian Ocean.

The U-boat deck gun was a high velocity 88mm, not a low velocity 75mm, and it was pretty rubbish at sinking anything over a few hundred tons.

Ah, the arming of merchantmen with AA. Lets see, when my fathers tanker did the Russian run they had 11 AA guns of various types plus a 4" gun. More heavily armed that any of the close escort apart from a destroyer...

A 40mm hole is just that - a 40mm hole. Something like the damage from a splinter. At least one cruiser came home with splinter holes numbers in the hundreds. Ships are large, and there aren't many vulnerable spots a hit that small has available. Compare that with a torpedo which can leave a 30x60 FOOT hole (on average)

If you are sending flights of 6 planes at a time to slowly damage one ship, you are going to take a lot of casualties. Among the aircraft.
 
After 1940, probably 90% of Atlantic traffic was escorted. Most of the rest was straggling.

The 60% figure might be for ALL shipping. It wasn't worth escorting ships once they left the NA - a few hot sports were occasionally escorted, often the 'escort was a Merchant Cruiser rather than A/S, the sub threat outside of the NA was low.
That might be a correct spotting, as I do recall clearly that the phrase did include 'all shipping', so do you think that this rather sweeping statement has given me, a two generation removed Yankee, a mistakenly drawn conclusion about the water off the UK in summer/early fall 1940? I don't mean within 200 miles of the shore, by the way, as that is within the range of any and every fighter in the UK, and so not a good place to send a 'ship hunter' group.

Escorted where in the ocean, and by whom? Oh wait, you said after 1940. Ok, then what about in 1940, between say historical fall of France, and when the late fall/early winter commonly made flying impractical? Still interested in exactly where in the ocean this escort was taking place. How was the mixture of merchantmen/escorts?

There is also the complex issue of are ships sailing together without an actual escort a convoy or not? Happened quite a bit in the Indian Ocean.

The U-boat deck gun was a high velocity 88mm, not a low velocity 75mm, and it was pretty rubbish at sinking anything over a few hundred tons.
Why do you keep comming back to the 75mm? And the 88mm was 'rubbish'? Why then did it start out as the preferred method of sinking a merchantmen at the outset of the war? And the 88 was to be used on a stationary ship, and fired from (for all intents and purposes) from the surface? I don't know how it stacked up against a cruiser's guns, but in terms of being cheaper to expending a few rounds rather than expending a torpedo, that trade off seems clear.

Ah, the arming of merchantmen with AA. Lets see, when my fathers tanker did the Russian run they had 11 AA guns of various types plus a 4" gun. More heavily armed that any of the close escort apart from a destroyer...
Congrats! Not everyone (myself included) can claim a parent fought in the war. My Da was 6 and my mother was born that spring. My grandpa's did serve, both of them, along with several of my 'great uncles', but most of them I barely met.
Back on topic, I have to ask when? And what years was this? And for a tanker? I should think that that would be one of the most heavily armed of all merchantmen, as it was a priority target, rather than a typical loadout, for any and every ship out there. And also, who was manning those guns? What training and experience did they have in summer 1940 shooting even at a windsock towed behind an actual aircraft? From the fact that you are talking about 'the russia run', to me this makes me think sometime after June 1941 at the earliest? Are my guesses comming close to the mark?

I am, of course, going to make the assumption (yes yes, an assumption) that your fathers ship never sailed on that run alone and came under air attack, so that the 11 AA guns were never put to the test, inasmuch as there would probably always be a warship in escort with AAA, right?

A 40mm hole is just that - a 40mm hole. Something like the damage from a splinter. At least one cruiser came home with splinter holes numbers in the hundreds. Ships are large, and there aren't many vulnerable spots a hit that small has available. Compare that with a torpedo which can leave a 30x60 FOOT hole (on average).
I have to ask a relitively simple question here, how much seawater will enter an unplugged 40mm hole per second? If the dual purpose AP/HE round detonates in a confined, watertight compartment, odds are it will no longer remain watertight. Does the detonation blow the door (hatch) right off, or mearly make twisted wreckage of it? If the hatch cannot be gotten around, does that mean that damage conrol cannot get to the whole to plug it? How much less watertight integrity does your average merchantman have compared to your example crusier above? What about young, able bodied crewmen, trained in damage control, to respond quickly to seal off these holes? Taking your example of a warship, how many extra crew (and lets be honest here, each of which is going to be far younger, stronger, and better trained than your average merchant seamen) are they going to have? Several hundred? A 1,000? More?
And this on a warship, where they expect to have to deal with combat damage, and have been designed not with cargo carrying capacity, but rather watertight integrity and damage survivability?



If you are sending flights of 6 planes at a time to slowly damage one ship, you are going to take a lot of casualties. Among the aircraft.
All I can say is, "REALLY"?:eek:
 
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hipper

Banned
If you Google Defensivly equpped merchantmen you will find most of the answers you seek.

If you buy a general naval history of ww2 you will find some details of convoy evolution, there are lots of free official histories on the hyper war website.

For the Germans to make a significant attack on merchant shipping after the fall of France they would have to invested pre war in a long range bomber

After the fall of France most shipping to the UK was routed to the north of Ireland

In real life the fitting of. 20 mm cannon discouraged low level attacks from the few Condor aircraft available
 
Ok, so one these mighty UK merchantmen, there will exist that most awe inspiring, most feared, and deadliest of all know AA weapons known to man...

"Grampa, with his coke-bottle spectacles, operating his antiquated deck gun, with which he has had no training, heroicly fires it to great effect, once again proving that the kilngons are not the only folks who can score a"

"Lucky shot, Sir"!:cool:

Sorry, I just couldn't resist that.
The artic convoys were beefed up with AAA and the guns were manned not by "my Grampa" but by men like his brother (my Great Uncle) who was seconded from 5th AA Division who completed his war landing with the 11th Armoured (D+7 Epsom, Goodwood, Bluecoat, Market Garden and liberating Bergen-Belsen)
I find your assertion quite insulting on two levels:-
Firstly this type of German/Nazi/Not-the-Nazis-but-do-as-well timeline dismisses any form of intelligent response from those ranged against your superior warrior race.
Secondly, you ignore the likelihood of people reading your witticisms who actually knew or knew and were related to those who fought in these campaigns
 
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