Shipbucket

just wondering - did you add the 150 tons additional displacement to the draft too? the ship might lie a pixel, maybe even several (no idea how heavy these ships are) deeper.

Hey Ace nice to hear from you,

I doubt whether 150 tons would change the draft lines by much. 1/50th of 20ft = 4.8 inches. Not even one pixel.

The E's were 7600 light and 9500 tons full load displacement. I would guess that the Formidable would be of comparable displacements with the 150 tons added in for 7750 tons and 9650 tons full.

Forgive me, I'm a pedant. Not even that much. The extra 150tons of water displaced is a thin layer at the waterline at the longest and widest part of the ship. Assuming the waterline section is an ellipse 170m x 16.6m the extra draft is only about 6.6cm.

Fantastic work!

I've had a dig through my photos, and your 3x2 7.5in is not completely unknown.
The 5-gun E had an estimated armament weight of 466 tons. The central pivot 7.5 on Hawkins weighed 46 tons so five would be 230, with another 70 tons or so for 100 rounds per gun, or 300tons, leaving 166 for 4x4in HA, ammunition and 4x3 21"TT
There was a proposal for a 5x1 7.5in version of Adelaide with single turrets. Estimated armament weight 560 tons.
Earlier single 7.5 turrets weighed 119, 135 or 157 tons depending on armour thickness, so they may have contemplated a Devonshire/Warrior/Minotaur mounting design, but with reduced armour plating, as even the lightest of five of those weighed 600tons and needed another 50 tons for 100 rounds per gun.
Lastly, in 1927, Lillicrap, then chief cruiser designer, produced preliminary estimates for a 6000ton cruiser with three twin 7.5in turrets.
For those, with 1in shields, he allowed 525tons (175tons each, including 14tons per gun for 100 rounds, giving a total armament weight of 725tons with 4x4in HA, 4 2pdr and 2x3 21in TT)
So, three twin 7.5s over 5 single 7.5s would need about an extra 225tons. That doesn't sound too much compared with your 150, but as always the real problem is not weight in itself, but topweight affecting stability. However, the larger 7.5 E had a displacement of 8850tons and length, beam and mean draft 607'oa x 58' x 17'3. Lillicrap's estimates were based on a hull of 490'x 51' x 15'3 for 6000tons, so 3x2 7.5 for a "super-E" seems quite possible, remembering that Enterprise had a twin 6in turret weighing 85tons, or about 105tons with 100 rounds per gun.
The only problem is carrying the 175ton B turret superimposed. It's not the RN's usual style, but the third turret might have to go aft. Compare carefully the bridge positions of Emerald, Enterprise and the two 7.5in versions, too.
The real problems arise below decks. The 7.5in ships with open-backed single mountings followed the general layout of Emerald, with separate magazines and shell rooms for each gun feeding ammunition separately to the space behind each gun. Enterprise had a much larger set of magazine and shell rooms directly beneath the twin turret, feeding ammunition centrally up the turret trunk for both guns. There is not room for this to be duplicated for two twin 7.5s forward (larger spaces anyway for bigger shells, or fewer shells per gun) without considerable rearrangement forward, including I think moving the bridge back. It's a new design, and has no amidships 7.5, so this is not impossible, but putting two turrets aft might be easier, though then there are problems with depth of hull above the four shafts to accommodate turret trunks and shell rooms. That was the chief technical reason which would have restricted rebuilding the Hawkins class with twin 8in to three turrets. The political reason was to avoid producing four more 8in cruisers so soon after Washington.

EDIT:
The 4-gun ship was the same size as Emerald. The 5-gun ship was 607ft overall, so I think your version is a bit short? Also looking again at your Formidable, you have done some of the things I suggest, but used the Emerald sized hull? That means you have squeezed three twin 7.5 turrets into a four single gun hull? Magazine space for two extra guns?
Legend displacements were Emerald 7550, 4-7.5gun 7700, 5-7.5gun 8850. The extra 1000tons was needed for the larger hull, with extra magazine space as well as the extra gun. Beam was increased from 54'6 to 58', presumably to deal with stability issues, but allowing 150tons more fuel than the 4-gun ship. Draft about 6in deeper. All these designs (except our twin gun ones of course) drew about 3ft more aft than forward, so they could probably stand two forward turrets without losing speed by digging the bows in.

I really like the twin turret version!

A few more thoughts. I've put them as an edit to my previous post. I think I have an advantage over you, K, as I don't think I sent you more than small drawings of the 4 and 5 7.5 ships, while I have some tabulated data. I hope you don't mind the comments - all in the interest of your excellent drawings being as near as possible to what might have been.

I really like them, especially in the latter guise.

Taking all the comments in from Smurf and others I have redrawn the 6x7.5" subject using the Fearless hull.





When you compare this version to the Hawkins class, which were of comparable size, I would much prefer to build these.

An interesting what-if design. Had their been no Washington Treaty, the RN would still have needed to counter the planned IJN 12,500ton cruisers, so these may well have come into existence rather than a County. A flush deck design with the forecastle extended all the way back would actually look pretty much like a County...