Tankovian Meta Thread

[Simon Tan]

We would buy CV707(aka Vesikko) but you lot have first refusal. We are going to order them from Voith-Crichton.

[Sardaukar]

Would Tankovia really need them, no.

Would they be useful, yes.

Might get Turkey peeved with possible interdiction of Bosporus Straight.

[Markus Becker]

On 9/21/2020 at 7:16 PM, Simon Tan said:

Tankovian Artillery (pre-Sept 1939)

Anti-Aircraft

Oerlikon Model S 20L70 (2cm Automatic AA Cannon M.29) Changed out from ST-5 based on earlier availability.

No procurement of Breda Model 30s as a consequence. Will go straight to Hispano.

 

Siege Artillery

Skoda Cannon NO vz 28 149L49 (15cm Cannon M29)

Skoda Mortar ON vz 28 220L19 (22cm Mortar M30)

21cm Morser 16 210L14.5 (21cm Howitzer M23)

 

 

I see your Oerlikon's earlier availability and remind you of the inferior performance of planes of the time. Furthermore the ST-5 has a more powerful round for AT use. 

I'm also not sure the 22cm Mortar M30 is needed. The 15cm M35 has the same range, is much lighter and has plenty of power against field fortifications. The M30 is certainly the better concrete bunker buster but to what degree is that ability tactically needed given the defensive nature of our military? 

And last but not least, for ages Lokomotiv has been lobbying for the Sturmgeschütz and now that we are up to our necks in tank production a Sturmgeschütz is desired. I guess we can prepare a design and a mockup but all production capacity is tied down in tanks, tractors and carriers for the foreseeable future. 

[Markus Becker]

My three cents on the navy.

 

The biggest item are the submarines and not just financially. So for the Tankovian Navy has not operated anything more complex than an armed trawler, which doesn't require a lot of skill at all. The move to torpedo armed fast attack craft seems simple enough because they are just a lot larger versions of MTB. The multi role escorts should be doable but submarines, I’m not sure. Now to the escorts:

 

Range: No point in the Black Sea is further away from Burgas than 650 nm, to Haifa is app. 1000 nm but you pass Rhodes at 550nm and Cyprus at 800nm. A range of 1,800 mn at cruise speed is very, very much.

Speed: The many Soviet coastal submarines can not be fast because they are too small, the larger probably have a top speed of 16 to maybe 18 knots like other nation’s boats of a similar size. A top speed of 24 knots is generous.

Armament: Given the limited size and the various threats the main battery gun need to be capable of low and high angle fire and must have a high rate of fire regardless of elevation. Minimum caliber should be 100mm. Anything smaller is of little use against surface targets.

 

Japanese 12cm/45 gun, weight 3 tons, RoF around 10 per minute, MV 830 mps

British 12cm/40 QF Mark VIII, similar to the Japanese gun except for the muzzle velocity(750 mps)

British 10.2cm/45 (10.2 cm) QF Mark V/XV, 2.2 tons without a shield, 15 rpm at low angles

American 12.7cm/25 weighs just under two tons, 15-20 rpm at any elevation but an MV of just 650 mps

 

The Japanese 12cm gun is the best against surface targets and can still be operated manually.

The British 10.2cm/40 and the American 12.7cm/25 have almost the same weight. The British gun has the higher MV but RoF declines when elevated above 62 degrees with the present mounts. The American gun has a higher RoF but the lowest MV, however it fires a heavier shell.

I like the American 12.7cm/25 best. Overall lowest weight and highest rate of fire. And RoF is critical, not just when fighting aircraft but also when fast surface ships are engaged and against destroyer size targets a 36 kilo shell is fully effective, while a 10cm shell is getting marginal. Add to that HMG or navalized 20mm ST-5 guns and a torpedo launcher and we are fine.

 

This should be possible on a sub 1,000 ton vessel. I’ll run this by some experts.

 

 

 

 

 

[Simon Tan]

You have missed out the Skoda 10cm/50 already in service with the Navy. Those are surplus low-angle mounts but the Italians (OTO) have developed a twin dual purpose mount with 85 degree elevation, RPC and power ramming. They have been quite successful in selling it with their cruisers to both the Argentines and the Soviets.

HMGs are pretty much useless as the airpalne will have dropped it's bombs on you long before you get into effective range. 

2cm automatics are the smallest caliber for anything more than morale purposes but 4cm has much more reach. The 40mm pom-pom is used by both the UK and Italy but the round is really quite slow. It is at least automatic , which the German, French and Skoda twins are not. The gun that is promising to be high velocity and automatic is being developed at Bofors with both the Poles and Yugoslavs waiting patiently. We should design for this and mount an ersatz gun in the interim, like say the Oerlikon. The Oerlikon is selling much better than the Solothurn.

I'm still trying to work out how we are going to fit out and integrate our weapon systems with US fire control and power systems. 

[Markus Becker]

I ruled out anything that wasn't in service at that time as no one could have known what worked and how well and it is 1930 when the plan is finally done.

.50 cal/13mm AA machine guns are still fine, 20mm cannons are great and the Bofors was but a very early prototype, so for medium AA single barrel 2pdrs are the best you can reliably plan with. 

That gun?

http://www.navweaps.com/Weapons/WNIT_39-47_m1924.php

Like the British one. Lower RoF, low shell weight, even with the new mount. Keep them in storage for mobilisation or use them as CD guns. The 12.7cm/25 is still the better gun for the new ships IMO. 

 

PS: The ships will be small. Tell whoever builds them that you don't want a tight design that has everything maxed out from the very beginning but instead something that has a margin for x tons additional equipment like maybe more depth charges or more fuel, more ammo, more AA guns and in that case space for the additional gunners. 

 

 

 

Edited September 24, 2020 by Markus Becker

[Rick]

On 9/22/2020 at 7:33 AM, Simon Tan said:

It is 1930 and the world economy is sunk. Tankovia is not exempt from its effects, though we are a little less disastrously affected by the evaporation of the essential lubricant of this engine, namely confidence.

Nonetheless, we have a Naval 5-year Plan in hand to build at least a squadron of robust escorts for our growing (temporarily suspended) fleet of oil tankers. With the primary terminus for these tankers being Poti and Haifa (oy vey our Jewish connections are very handy), this is the desired cruising range for our escorts. They should be able to travel to these ports without bunkering along the way.

Poti is a scant (650 nm) compared to Haifa (1300nm). So a range of 1,800 nm should be more than adequate.

The escorts will not need to keep up with a fleet but they will need enough speed manoeuvre against threats, especially submarines. So a top speed of no more than 24kts is adequate.

An escort needs to defend her charges against surface, subsurface and aerial attack. The last is something that was not really addressed in the Great War to much extent.

Subsurface threats require the use of hydrophones for detection and depth charges to attack.

Surface threats are seen off with either guns, or torpedoes to deter large combatants from closing.

Aerial threats are countered with Anti-Aircraft guns. 

The US Ambassador has suggested that we order our vessels from American yards, who are going through a very tough patch. This is not nearly as improbable as it seems, since by doing so we could likely extract some concessions as far as the Smoot-Hawley Tarrifs for our exports to the US. 

About those tankers. In 1927, the U.S was using about 6 1/3 barrels of oil per person per year. If Tankovia uses about half of this amount, per earlier posts on population, then Tankovia would need about 60 oil tankers for all of its annual petroleum needs. If considering tankers, consider Galați shipyard, Romania. More about this shipyard in my next post.  Railroad tankers of this era were typically of 143, 190, and 238 barrel sizes. 

Haifa port was not open till 1933, in 1908 oil was found in significant amounts near Masjed Soleyman near the Persian Gulf. This oil would be going to Britain and France, especially for the Royal Navy via said gulf. Further discoveries of oil reserves across the region were Iraq in 1927, Bahrain in 1932, Qatar in 1935, Saudi Arabia and Kuwait in 1938. The nearest reliable and probably economical source of oil for Tankovia would be from the port of Novorossiisk. Tankovia could lease tankers as the largest exporters of oil in this period was the U.S., Venezuela, and Mexico if the Russian angle doesn't work out. 

As a side note, it may be worthwhile for a tanker or two to be fitted out as a "Q" ship. Not so much vs submarines as vs warships using below water line torpedo tubes. Well get back to naval combatants later, but for an effective navy for a small country with a limited shoreline I would:

1. Have a unit of airplanes on an night capable, all-weather airfield by itself who's sole duty and training is for anti-shipping duties and more important, ship identification. Said planes do not need to be the most modern available.

2. Consider small, helium filled blimps for coastal surveillance and possible bombing. 

3. Set up an attache office for Italy and Britain, possibly the U.S.

4. Realistic training will show it is difficult to hit a ship from a plane, this is where the U.S.N. dive bombing techniques will come into use. 

5. In this time frame, Italy has a surplus of 18" torpedoes and experience using MAS boats, although hitting a moving ship is difficult with a torpedo boat.

6. A final consideration is a monitor type coastal battleship. 

 

 

 

[Simon Tan]

You are considering it from a consumption viewpoint. The Burgas refinery is as much for re-export of refined products as it is for domestic consumption given the limited size of this market. The longer term business is as a gateway for Soviet crude and the financial activities relate to it. Crude from the Americas is very much a token given the cost of shipping it but it is important to establish the bona fides of Tankovia as a neutral and open refiner.

1. The Air Force and Navy have established a joint Maritime Patrol Squadron based out of Burgas Aerodrome. The Navy sends it's airmen to the Air Force for training and provides ground crews for maritime patrol aircraft. Seaplanes are presently being evaluated for this role. The number of seaplanes being produced is boggling but the Procurement Committee has determined that it will be a multi-engine parasol winged seaplane with an enclosed cockpit. We do not share the Italian predilection for open cockpits. It's probably going to be the Consolidated P2Y, unless it drags out and the Do24 comes into play.
2. We have tethered observation balloons of the Caquot type used for border observation. It is proposed to try one of these tethered to a ship for the same. (these are called kite balloons FWIW).
3. Our attache offices are numerous, if a little sparsely staffed. I must admit to being Francophile in terms of things naval. They have such pretty ships.
4. At this juncture (early 30s) we probably do not have the resources to stand up a dedicated anti-shipping Squadron.
5. MAS boats are probably too small for our needs. They will have been purchased for evaluation.
6. Manning and availability dictates against this for a new build. The Navy does seem to be 'weak force' by necessity.

[Markus Becker]

Do we need a flying boat for maritime patrol? The Black Sea is not the Pacific Ocean and we have an airfield at Burgas. We could use Savoia-Marchetti S.71. Certainly for the training period. They are night and all weather capable and Air Tankov - who are also at Burgas – has purchased four to amend their Ford Trimotors.

Another item in the naval plan that might need to be reconsidered are the Schnellboote from Lürssen. We could to change that to costal ASW/minesweepers/gunboats of the R-class. A ~100 ton boat could reach 21 knots with diesel engines and mount a fair number of automatic guns.

 

[Simon Tan]

To parphrase the Vice Admiral, "They take off and land on water and thus are naval vessels!". The Navy is keen on them for more autonomous operation but also the ability to conduct search and rescue from the air. This is particularly desirable given then increasing amounts of pleasure boating and even cruising on the Black (Sea) Riviera.

The 'Maritime Patrol' moniker was of course to reduce the level of resistance from the Air Force. It will eventually be shortened to the Maritime Squadron. 

We are of course gratified to see the growth of private air travel but I surmise that Air Tankov would like to lease us their FOKKER Trimotors in the period of economic decline worldwide. I have no idea if their pilots and ground crew are citizens or just residents with work permits. That being the case, perhaps they would like to enlist in the Navy. 

The Navy would of course like to have both the S-boat and R-boat. One the positive side, they essentially draw from the same maintenance pool, being wooden, diesel-powered and German. 

[Rick]

Now that the need for aviation has been established let's briefly consider the planes and the time era. With attaches in Berlin, London, Paris, Rome, and Washington D.C. beginning in the early 1920's I would recommend ex-WW1 single engine planes as Tankovia is in the developmental stage of airpower.

 The 1930's would be the time to replace the WW1 planes. I would think that the biggest problem would be the monoplane vs biplane fighter. Imo, the advantages of the monoplane were not so apparent untill about the 1930s.

Since Tankovia has limited airspace, single engine planes would suffice. For reasons of economy I would recommend fighter planes as said planes could also suffice for light bombing attacks. By the late 1930's there are a number of monoplane fighters that could fulfill this role and the ability to carry larger bombs also increases. If Tankovia insists on torpedo attack airplanes, I would see if she could acquire some ex-U.S.N. biplane ones, or better yet the Swordfish. 

Switching from air to sea, an agreement is set that a naval aviation unit is established. For naval vessels, Tankovia has acquired some old, ex-WW1 examples. For early 1920's training these will suffice. Again, for reasons of economy and realistic threats I would consider:

https://blog.twmuseums.org.uk/p-boats-of-the-first-world-war-william-bartram-and-p23

https://www.usni.org/magazines/proceedings/1973/june/eagle-boats-world-war-i

https://en.wikipedia.org/wiki/USCGC_Tampa_(WPG-48)#CITEREFUSCG:_Saranac,_1930

Of the three, I would favor the P class and obtain one of the U.S.C.G. cutters for larger vessel familiarization. The P class, with its long quarter-deck can be switched from a gun boat , torpedo boat(using Italian 18" torps), a mine layer, or as a coastal mine sweeper. Once knowledge of using the U.S.C.G. cutter is acquired, I would highly recommend this ship: https://en.wikipedia.org/wiki/NMS_Amiral_Murgescu

For what ship building and repair knowledge Tankovia lacks I would highly recommend the Galați shipyard in Romania.

If a small torpedo craft is desired I would suggest Tankovia build its own. Small, wooden craft with large gasoline engines would be within the county's technological an economic ability and would acquire local knowledge and jobs. Also, the opposite lack of technological and economic abilities would prevent the effective operation of submarines. To everyone's favorite-- guns. The U.S.N. 5"/25, imo, would be a poor choice. To successfully use this gun, you need a good director and such items would weigh to much except on a larger vessel of about 1,000 tons. And then you could only mount one director and I would say three 5"/25 guns, with little armament for any thing else. Any reliable weapon in 4" caliber with a low-angle director would be good for the Black Sea. Such a caliber does not require below deck space for efficient use and would be a good balance between H.E. load, range, and man-power loading in not so calm seas. 
In this time period, no one has an effective solution for the use of large caliber guns, ie 4" to 5", in the a.a. role.  I would say the U.S.N. comes close with the Mk 33 and especially the 1940's Mk 37. The R.N. comes in second with its High Angle Control System. The odds of a higher flying plane successfully bombing a naval vessel is small. For this time period the main worry would be low altitude attack aircraft. Unless Tankovia is flush with 20mm guns with good ammo fuzes, and since the Navy would be second fiddle to the Army, I would think most naval craft would be armed with twin 13.2 mm machine guns. With tracer ammo this would probably suffice until WW2 begins.  I would practice using the 40mm type weapons and directors on the cutter until proficiency is obtained as such a director/ multiple barrel weapons combo takes up a surprising amount of weight and space and manpower. 

On Tankovia's oil tanker fleet I would put a few twin heavy machine gun gun tubs on them, the forerunner of the "fitted for but not with" doctrine. Except for a 3"-5" gun on the stern, I would not put any larger guns on a tanker. For  it is much better to run away and deliver oil than choosing to fight on a slow, not very maneuverable vessel filled with a flammable substance. Don't forget the anti-surface tanker "Q" ship.

By all means, provide radios and a doctrine for quick, coded messaging for the fishing fleet as these boats can provide clear weather notices of vessels approaching. 

The quantity of said planes and naval vessels depends on the technological knowledge and number of such personnel available to make effect use of these weapons. 

 

 

 

 

 

[Simon Tan]

I think you must have missed the earlier post where the Navy was greatly expanded in the 1920-22 period via the procurement of a number of ex-RN sloops that were practically unused, namely 2x24-class and 4xKil-class. This will carry us through well into the early 1930s, which is when we start looking for a new construction escort vessel. (see above) The USN doesn't engage in vessel dumping till much later.

We actually have to crash into this because of the Russian Civil War and Greco-Turkish War. Our vessels are initially crewed by Austro-Hungarian and British 'specialists' looking for work after demobilization due to the fledgling state of the Navy at the end of WW1. Normality does not really return till the mid-20s after the Soviets and Kemalists tighten their grip on their countries and by extension their waters. 

Indeed this experience is what turns an opportunist action into policy.

Routine maintenance is done in Burgas , which has perfectly serviceable maintenance yards and docks. What we don't do much of is fabrication and construction. As the primary port of the country, these would have been steadily developed. 

It is pointless to try and construct motor torpedo boats domestically as long as we don't produce aero engines. And by the time we do (see Hispano), we will have come to the conclusion that marine diesels are a much better idea. 

 

[R011]

It sounds as if your looking at something much like a Hunt Class.  That particular class comes a couple years too late and the first block had issues, but it shows that a twenty-five knot escort destroyer with reasonable gun and torpedo armament is quite possible on a thousand tons.  I'm sure any decent ship design bureau could draw up something suitable.

[Simon Tan]

To be precise a Type IV.

[Simon Tan]

Meet the M1940!

Edited September 27, 2020 by Simon Tan

[Simon Tan]

http://www.vhu.cz/exhibit/ceskoslovensky-letecky-kulomet-vz-30/

This is the vz.30 MG used on the Avia B.534. Tankovian aircraft use FN-Browning MGs.

[Markus Becker]

As far as I know seaplanes can not operate from the open seas unless they happen to be very, very clam. If they are not they can land but not take off, thus seaplanes bases are located in inlets or bays. If so, their capability for search and rescue would be limited to search and dropping life rafts. Things landplanes can do just as well.

With regard to using Savoia-Marchettis I was thinking of logistical advantages like easier maintenance and maybe we could get better conditions as we already bought some. The Trimotors have a substantially shorter range, so I'm not enthusiastic about them as MPA. 

There is one important difference between the R- and the S-boats. Only the former have diesel engines, the latter are still using petrol engines, though the first S-boat with a diesel is scheduled to enter service next year(1933). We could go ahead and buy R-boats and add diesel powered S-boats at a later time.

 

 

Rick, one or two pages back Simon stated that the navy purchased two 24 class and four Kil class sloops.

The weight penalties of dual purpose guns and director control would also apply to 4” guns I presume? If one goes for LA only guns, the older 10cm Skodas would be all right but I still like the 12.7cm/25 for its weight, shell weight and RoF. One could use them without a director and have a light weight, heavy hitting, fast firing LA gun that could engage aircraft under local control. Horribly inaccurate but its a free extra feature.

 

[Simon Tan]

How did Air Tankov come to buy those S.71s? They only built 7 and those were for Ala Littoria (airline owned by the Fascist Italian state). Also their first flight is in 1930. It seems like a very unlikely purchase but I could be convinced with a story about Mussolini etc. 

You are thinking about float planes and not flying boats. Flying boats like the Sunderland, PBY Catalina and Do24 performed on water pick ups. This was their main value in maritime SAR. They operated in the North Sea so the Black Sea is eminently doable. 

 

[Simon Tan]

What I have not been able to find is interwar construction of foreign naval combatants in the the US interwar.(!)

[Markus Becker]

3 hours ago, R011 said:

It sounds as if your looking at something much like a Hunt Class.  That particular class comes a couple years too late and the first block had issues, but it shows that a twenty-five knot escort destroyer with reasonable gun and torpedo armament is quite possible on a thousand tons.  I'm sure any decent ship design bureau could draw up something suitable.

 

Looks like it. Spica class: Ten knots faster than required, three single 10cm LA/HA guns, plenty of light AA, torpedoes and still just 800 tons standard. 

Ours could be: 24kn, 3*1*10cm LA guns, 4*1*2pds*, 6(?)*1*13mm HMG, 1*4*45cm launcher 

 

*to be replaced later by alternate history's default medium AA gun.  

[Markus Becker]

14 minutes ago, Simon Tan said:

How did Air Tankov come to buy those S.71s? They only built 7, no 11 and those were for Ala Littoria (airline owned by the Fascist Italian state). Also their first flight is in 1930. It seems like a very unlikely purchase but I could be convinced with a story about Mussolini etc. 

The Trimotor carries more passengers but over a shorter distance. The S.71 is on the longer routes. Their recent purchase was to replace the Junkers G24 with something new that is also more economical. The Hellenic Air Force was looking for inexpensive transport planes and Savoia-Marchetti probably wanted to get a foot in the door. S.55 show up more often than they used to. Even General Balbo visited. 

 

Quote

You are thinking about float planes and not flying boats. Flying boats like the Sunderland, PBY Catalina and Do24 performed on water pick ups. This was their main value in maritime SAR. They operated in the North Sea so the Black Sea is eminently doable.

Hm, the S.55 isn't brand new but it's good at what it does. I wonder if Italy accepts payment in coal, the USA would not, I guess. 

[Simon Tan]

The Italian Spicas,the French Malpomenes and RN Kingfishers were built to exploit the absence of tonnage limitations in the Washington Treaty for vessels under 600 tons. We are under no such restrictions and should not use these designs, which are very tight and not very stable gun platforms and all guns are manually worked.

All major navies are moving to director control for both LA and HA. The Americans seem to have got there first for HA with the Mk19 director, which is only found in 1930 with on CA and larger. The visible element is the director tower with the optical range finder and the tracking controls. The actual computation is located below decks and the information transmitted to the gun positions. 

In an ideal situation, the laying is done automatically with director control but that is not yet possible. Presently, gunners
have to lay the guns based on matching data transmitted to dial displays. Manual laying will degrade over time with fatigue, accelerated by the overall mass of the mount. A dual-purpose mount(DP) with the ability to engage High Angle is simply going to be heavier with higher trunnion height. Without a powered rammer, rate of fire rapidly falls away at high elevations, a problem seen with most pedestal type DP mounts. Then you have automatic fuse setters which are ideally on mount to minimize the delay between setting and firing and you quickly get to a point where a fully manual mount ceases to make sense. Especially in a small navy with few vessels. 

RPC and all the modern amenities for a single is not a whole lot more than for a twin mount so the latter makes a lot of sense. The higher mass is offset by the corresponding reduction in centreline spacing and superfiring provision. 

So, we should have at least 2xtwin 10cm, ideally 3xtwin 10cm mounts. Base ring mounts are ideal but probably beyond us so RPC powered pedestals with external ammo hoists and ready magazine is probably has to be. The people to go to for this are the Americans, as they have by far the most experience with RPC. We just don't want their 4" gun.

The Bofors cannon currently being developed has tremendous potential but it is not yet ready. It is proposed to chamber the Bofors 4cm into the Skoda twin 4cm/70 manually loaded guns as fitted to Dubrovnik, the Yugoslav DL.

As far as light AA, I'm still keen on the Oerlikon vis the ST-5. If you insist on AAHMG, at least have them as twins and watercooled (the one thing we should not be very short of at sea).

Torpedoes should be common to whatever we mount on MTB and submarine, i.e. 21".

The London naval attache has given us a shortlist of British yards that might be interested to do this Escort Destroyer. One of them is Thornycroft in Southampton whose HMS Amazon was selected to be the standard pattern destoyer for the RN.  I have asked the Navy to send a team to begin evaluation and negotiations. 

So;-

ESCORT DESTROYER 1930/1

• 2/3x2 10cm DP
• 2x2 4cm AA
• 4x1 2cm AA or 4x2 13mm AAHMG
• 1x 3 533mm(21") TT
• 2x DCT
• 2x DCR

24 kts deep load, steam turbines TBD.

Displacement, as needed to achieve this.

One a year from 1933?

[Simon Tan]

For the flying boats, why don't we start with the Dornier Wal? 

[Markus Becker]

I just mentioned the Spica class to underline what is possible with a standard displacement of under 1,000 tons, not as something that should be copied.

 

With regard to the proposed design. Your’s is IMO second generation, something you’d see in the mid to late 1930s. Circa 1930 airplanes are not that much more advanced than in the past and thus the overall air threat is limited. That would change very quickly as we know now but that is hindsight, isn’t it? Thus my more conventional proposal. In the meantime I have been doing a bit more looking around and noticed that RN sloops had 4” HA/LA guns. Without RPC and director control but that’s still a substantial AA armament for the time and the 2pdrs are also useful for firing down on submarines and disposing of MTB.

1^st gen: 3x1x10cm HA/LA guns with FCS like on contemporary slops/DD, 6(?)x1x13mm HMG or 20mm guns. The design is fitted with the 2pdr but designed for the 40mm Bofors. One ordered in 1933/and 34 each.

2^nd gen: What you proposed. And yes to 53cm torps. The 45ers have not nearly enough range.

If the ships are ordered in the UK I recommend going with their 4” guns. The 4”/45 Mk V on gen one and the Mk XVI on gen two.

 

 

[Simon Tan]

The Italians have been busily building a large number of destroyers with twin gun mounts since the mid 20s. These are 4.7"(120mm)/50 LA mounts. These are RPC equipped and weigh 20.2mt. The contemporary twin DP 10cm from their CAs are 15mt. We already made the decision to go to DP mounts instead of separate LA and HA batteries so it's not really a leap. 

Manually worked 4"QF is not going to meet our requirements. AFAIK, no MkXVI mounts were exported before WW2. The demand from the RN and Commonwealth navies meant there were never enough to go around. British yards did not have a problem with foreign equipment. 

The good news is that we won't be John I. Thornycroft's first foreign naval customer. That would be the Chileans. Alternatively we can have them built in Italy, what with the obviously intensive lobbying.

 

 

Edited September 28, 2020 by Simon Tan