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Hood
Post subject: Atlantic Cruiser 1912/13Posted: July 3rd, 2016, 10:00 am
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In 1912 false reports of German cruisers with guns larger than 170mm (6.8in) for commerce raiding led the First Lord, Churchill, to ask for a counter in case the information was true. The DNC, d'Enycourt drew up three studies during 1912 (Brown cites the head of cruiser design, William Berry, having designed these but the designs all feature in d'Enycourt' workbooks, Berry's have not been found so there is no conclusive proof of his input and influence) followed by two more in July/August 1913. Details are sketchy, information here comes from D.K. Brown’s The Grand Fleet and Norman Friedman’s British Cruisers. Friedman cites a slightly different genesis, namely d’Enycourt’s 1912 report on replacing the armoured cruisers currently on foreign stations, Germany’s 1912 Naval Law planned ten foreign service cruisers so the Admiralty should build twenty new ships to counter on a two-to-one basis. Friedman cites B3 as the response to the rumoured German 170mm armed cruisers. The designs were entitled ‘Light Cruiser for Atlantic Service’.

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Design A

6,150 tons (deep); 500ft long; 40,000shp for 28kts, oil fired boilers; 2x1 7.5in (Mk V?) and 8x1 6in Mk XI (50cal) and 8x1 12pdr, 2x 21in TT (uw); armour 4in main belt tapering to 2in aft and to 3/2/1in forward; estimated cost £550,000.
This design was probably rejected because the armament was too light. The 7.5in was probably fitted to counter the German 170mm gun and its sustained rate of fire would have been about 3rpm, the turret was a lighter version fitted to armoured cruisers with 4in armour and barbette. Without fire-control equipment Brown estimates these ships would have been unlikely to have scored hits at ranges over 6,000yds.


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Design B1

8,150 tons (deep); 540ft long; 40,000shp for 28kts, oil fired boilers; 4x1 7.5in and 8x1 6in and 8x1 12pdr, 2x21in TT (uw); armour 6in main belt tapering to 2in aft and to 3/2/1in forward, upper belt 4in and 3in over casemates; estimated cost £750,000. Unusually the bulk of the 6in battery was located in casemates. This design was probably rejected because it was too expensive but it did combine heavy armament, armour and high speed.


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Design B2

8,000 tons (deep); 540ft long; 40,000shp for 28kts, oil fired boilers; 4x1 7.5in and 8x1 6in and 8x1 12pdr, 2x 21in TT (uw); armour 6in main belt tapering to 2in aft and to 3/2/1in forward and upper belt 4in; estimated cost £740,000. This design was also rejected because it was too expensive. The casemated 6in of B1 were replaced by a single 7.5in turret and the 6in moved forwards in the usual shielded mounts except for two casemates aft (these are missing on Brown's sketches but are obvious on the original sketch plan).


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Design B3

7,400 tons (deep); 540ft long; 30,000shp for 26kts, oil fired boilers; 8x1 7.5in and 4x1 12pdr, 4x 21in TT (uw); armour 4in main belt tapering to 3in aft and to 3/1.5in forward, upper belt 3in; estimated cost £700,000. In July 1913 d’Enycourt submitted a new design with all-oil fuel, a uniform battery of 7.5in guns, the turret being slightly lighter than A, B1 and B2 with 3in armour. Unlike the earlier designs, this design had four underwater torpedo tubes, fore and aft of the machinery spaces. Although the armament was much more powerful, reducing speed by 2kts cut the costs by £40-50,000. The Third Sea Lord liked the design, comparing very favourably with the County Class armoured cruisers despite being smaller and lighter. Churchill however felt it was too big and expensive and disliked the ‘Atlantic’ title.


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Design B4

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Design B4 with straight funnels and masts as requested by the Board

Figures in parentheses [] are for a mixed-fuel version: 6,500 tons (deep) [7,000 tons]; 510ft long; 30,000shp for 27.5kts [28,000shp for 26.5kts], oil fired boilers [coal-oil]; 2x1 7.5in , 6x1 6in, 4x 21in TT (uw); armour 4in main belt tapering to 3in aft and to 3/1.5in forward, upper belt 3in; estimated cost £548,000 [£588,000]. Developed in response to Churchill’s criticisms of B3, B4 was offered in both oil-only and mixed firing versions and was smaller and cheaper and was closer to the scout cruiser origins of these designs with centreline 6in armament and a superfiring 6in in B position, pre-dating that of the later Ceres Class by three years. Once the reports of German cruisers were realised to be incorrect these ships were soon dropped, although the design work was approved. A few years later the same requirements in wartime would bring the ‘Improved Birmingham’, the Hawkins Class into existence.

Drawing Notes: these are all drawn from sketches of original plans in D.K. Brown’s The Grand Fleet and Norman Friedman’s British Cruisers and copies of the original sketches. The sketches of B1 and B2 had least details regarding locations of funnel and masts so these have been estimated based on location of boiler rooms etc.
Many thanks to Smurf for much additional information on these ships to clarify certain errors and omissions in Brown and Freidman's accounts.

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Last edited by Hood on July 10th, 2016, 10:54 am, edited 4 times in total.

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Krakatoa
Post subject: Re: Atlantic Cruiser 1913Posted: July 3rd, 2016, 10:21 am
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Usual high quality drawings from a Shipbucket Master.

These cruisers look like enlarged Town Class of the same period. I can't say I like any of the designs too much. Did they not learn from Dreadnought, all 6" or all 7.5", the mixed armaments would have been useless. The German 6.7" were on the Deutschland Class PD's so it was possible the gun could have gone on to cruisers, in which case the 5x7.5" armed ships would have been the natural opponents.


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mortarigus
Post subject: Re: Atlantic Cruiser 1913Posted: July 3rd, 2016, 12:25 pm
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It took a lot longer for the cruiser connection to be got right, probably because the advent of the battlecruiser rendered the armoured cruiser obsolete. The experience of these ships at Jutland made this point dramatically clear. It is fair to say that these are the precedesesors of the post W.W.1 heavy cruiser and show their transitional nature, demonstrating just how tentative the design thinking is. The German Scharnhorsts' were probably the best balanced of the armoured cruisers with many of the others being hindered by an unbalanced armament and all with triple expansion engines, certainly turbines made a big difference. Still this a very interesting post, I have often wondered about early heavy cruiser thinking. Thank-you for this Hood


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emperor_andreas
Post subject: Re: Atlantic Cruiser 1913Posted: July 3rd, 2016, 12:59 pm
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Very nice work!

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smurf
Post subject: Re: Atlantic Cruiser 1913Posted: July 3rd, 2016, 11:29 pm
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Hi, Hood. These are very interesting ships, but some adjustments may be needed.
D K Brown wrote a little more about them in World Ship Society 'Warships 158' June 2008, but some errors crept in when the article was not published until after his death.
There is a Ship's Cover No 319, and more details in Tennyson d'Eyncourt's notebook in the NMM Caird library. Neither DK Brown's articles, nor Friedman's book are free from errors. I did have some correspondence with DKB and the editor of Warships at the time. It will take me some time to retrieve my notes (on a backup hard disc I hope!) and then to compare them with what you have written.
To begin, on what did you base the 7.5in turrets? The originals are as you say 'sketchy'.
The ships lie between the 5400 ton Towns with 8 or 9 6in, and the 9700ton Hawkins, in both date and size. The 7.5in guns would be the Mk VI as used on Hawkins. That means a light gunhouse, though perhaps one more enclosed than Hawkins was the intention in 1912. There is certainly not room within the armament weight for 8 armoured turrets of the type mounted on Minotaur for her MkII 7.5s. Nor does the Atlantic cruiser's beam of 52ft provide much room for proper turrets either side. Minotaur's beam was 74'6. Power of both Minotaur and the Atlantics was about 27000hp so space needed for boilers and machinery would be comparable. Also, the earlier turrets had elevation of only 15 degrees, while Hawkins gunhouses and central pivot mounts allowed 30, very necessary for a commerce protection cruiser to enter service in 1915 or 1916 to engage German raiders armed with 170mm guns even if those turned out to be mythical. IIRC there were some unbuilt Austrian designs with such guns, so intelligence was not completely faulty. German cruiser guns early in WWI generally had been given higher elevation than their British counterparts.
Friedman says 'single turrets', and has drawn mountings with trunks extending downwards to the magazines. but so far as I recall, there is no written description and certainly no more detailed drawings than those in Brown's 'Grand Fleet'. Friedman's plan views must be his own extrapolation to match the simple profiles.
More by e-mail when/if I find it.


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erik_t
Post subject: Re: Atlantic Cruiser 1913Posted: July 4th, 2016, 12:46 am
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For those of us who are more of the 1935-and-later mindset, an interesting reminder that what we know as cruisers were entirely a construct of the interwar naval treaties. It's interesting to contemplate what evolutionary direction they might have gone otherwise.

And nice drawings, obviously!


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Gollevainen
Post subject: Re: Atlantic Cruiser 1913Posted: July 4th, 2016, 6:16 am
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really nice ones, havent known about these before

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Hood
Post subject: Re: Atlantic Cruiser 1913Posted: July 4th, 2016, 7:50 am
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smurf,
I knew you'd be able to dig some more out on these!
The plans are very sketchy in Brown and Friedman's sketches of B3 and B4 seem quite detailed in their internal arrangements, whereas Brown just shows the armour scheme and some machinery room spaces. I assumed that Friedman may have seen something more detailed for those two designs at least.
My 7.5in turret is based off the size and shape shown on Brown's sketches, he certainly says enclosed mounts in his text, so I'm assuming they are some form of turret but probably very lightly armoured (1-2in max?). I went with the 6in turrets on the later armoured cruisers for style inspiration and added a sloped roof (the sketches seem to imply a sloped roof in some of the drawings) and sloped turret roofs were in vogue at that time.
Only B3 has beam turrets, I must admit they seem overkill on a hull this size. Your point about elevation is well taken. I wonder whether any planning really went far enough to consider the type of mounts required for the role? As I say in my intro, 6in 50cal seems to have been desired but by 1913 light cruisers were already receiving the handier Mk XII. I wonder if these were simply placeholders for the design to be worked out if work progressed?
The 12pdr battery seems heavy on the A and early B designs, Friedman says B3 had four HA mounts but that seems unlikely given the time and there is no mention of any lighter guns for B4.

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smurf
Post subject: Re: Atlantic Cruiser 1913Posted: July 4th, 2016, 9:26 am
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Hood said " I wonder whether any planning really went far enough to consider the type of mounts required for the role?"
Exactly. But I do know of some other clues.
A 70 degree elevation 12pdr mount was being developed in 1911 for use against airships. All six mounts in the Birmingham class were considered to give all-round cover, but the scheme was not pursued.
The Atlantic sketches in d'Eyncourt's notebook are his own hand drawn. I am quite convinced that there are no more detailed drawings - at least none surviving, and probably none ever beyond d'Eyncourt's own. Compare his U and W sketches of R class battleships. However there was a study of versions of HMAS Adelaide with either 4 or 5 7.5in. These got as far as outline sketches - draughtsman drawn tracings about 8in long. Those showed enclosed mounts rather than Hawkins type, but the tracing was in bad shape, very yellowed. But it does give a picture of shape and size.
There is a Cover note about the Atlantic design which says that the machinery was "same type as that of the light cruisers now being constructed [Towns] but rather heavier with less full power .. for reliability" so Friedman does have something to go on for internal arrangements, but not more detailed drawings.
You will have gathered that I have found at least some of my records, so expect an e-mail in the not too distant future, with sketches to work from and more extensive notes.


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smurf
Post subject: Re: Atlantic Cruiser 1913Posted: July 4th, 2016, 11:32 am
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The Admiralty Form A schedule for B4 Atlantic cruiser lists 4in + 3in armour for the gunhouse. Eight of those looks a bit heavy for a 6000ton ship with total armament weight 1090 tons. I need a rethink over what I said above!


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