Shipbucket

A good drawing which illustrates really well how cramped this design was aft. I can see why you wanted smaller turrets, though I don't go for your invented "twin MkXVI" for Diomede's mount was a weatherproof shield, not an armoured turret.
Are you going to do N3, which was lengthened 50ft on M3, mostly aft. You can see why!

I don't think speed was a serious issue, remember the plan was to build four battleships and four battlecruisers. The battlecruisers which became the G3s were exceptionally good ships too, in fact D.K. Brown rated them as good as any capital ship built during the Washington Treaty and after, even compared to Yamato and Iowa. The Ms were not ideal ships, the 18in was too powerful and probably had a very poor barrel life, blast was a serious issue, the ends were highly vulnerable and the design was cramped aft, but it was a stepping stone.

Thanks to additional information from smurf, I have edited the drawing with new 6in turrets based off 1921 drawings of such turrets for the G3.
I do intend on doing several of the these designs, after M3 I plan to do the L2 and L3 initial designs (before the transom) and then others of the series, but probably not in order. The pom-poms are still stand-ins for the planned ten-barrel mounts which became the eight-barrelled we know and which are fitted here (you'll have to imagine two-rows of five!), smurf's research indicates a six-barrel experimental mount may have been fitted when these ships completed and I hope to draw this part too for future use.

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The transom would not be effective in increasing speed at 21 knots. In fact it would decrease efficiency and so range at that and lower speeds.
Tests showed the crossover was at about 25 knots. Therefore the transom on M2, M3 was either (or both) to increase space well aft or to keep the ship short for docking reasons. The preceding L and K classes were too big for almost all existing docks. Campbell's Warship No2 article has a section devoted to which docks, including floating docks, were suitable or nearly so.

D.K. Brown says the transoms probably originated from a comment by (possibly) d'Encourt who felt as the stern of the L's were only kissing the water, they could be cut. It seems an earlier transom had been tried at Haslar for the battlecruiser design AR in March 1920. The forms tried were cut off at 30ft aft of the after perpendicular and then 15ft and then at the rudder. The first two were satisfactory and even the third only had a slight penalty. It seems the efficiency problems at moderate speeds was recognised about this time too. Brown points out that it gave this series the performance of a ship some 20ft longer and the broad transom helped in preserving damaged stability, a key factor given the large unprotected ends of the designs.

Also, I must confess an error with the posted drawing, the forward 6in mount should be one deck lower, inside the lower deck of the superstructure. I will revise this once its clearer what layout and mount was intended there.

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The discussion in Grand Fleet illustrates the difficult problems with the 1920s capital ships, trading off different advantages. His comments relate to the L series, with speeds of 25 -26 knots, high then for battleships, but just about fast enough to benefit from a transom. The transom helps the Ms to overcome the problem of 'soft ends' but by eliminating the one at the stern rather than by widening the ship. The armour in the Ms must go close to the stern to cover the engines. On the downside, if the ship is wider and holed, flooding of compartments near the hull sides increases the turning moment towards capsize compared to a ship in which those compartments were nearer the centreline. The Didos and Arethusas were vulnerable to that, but theirs was a design fault amidships allowing rapid flooding.
I looked at the Haslar reports when writing about the Fijis "One effect of the transom was a quite sudden and pronounced change in the pattern of flow around the stern at a critical speed in the region of 25 knots (somewhat different values being observed for that depending on whether the ship speed was increasing or decreasing through the critical speed)". In their case the transom was introduced to increase their top speed.

Very nice drawing and good discussion ! I hope you will do the H3 and it's versions as well Sir!

Marvellous drawing Hood, she looks like one tough mother.

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Thanks guys.

I have posted a revised version of the M2 with corrected forward 6in battery and revised forward superstructure and other minor changes, though I admit I'm not yet 100% satisfied with its layout. However, I'll probably make any further refinements with the M3 [currently 80% complete].

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Never-Were British Aircraft

Being these were just preliminary drawings I'm wondering what changes would have to be made if these designs were to be built...

eltf177 I think the only really significant changes would be to the secondary armament.
There is a drawing by Alan Raven in Warship 4 of the G3 depicting its appearance if built to the original design.
The 6in guns are arranged as Hood has depicted the forward guns in M2. The initial version had a heavy tripod mast right aft, and minor differences in the positions of director control towers, with the bridge lower than the final version.
In other words, 'hard to say'.
Comparing similar stages for the KGV design, there were major changes: a twin turret in B position replacing a quad, and 8x2 5.25in replacing 10x2 4.5in secondaries.
'The root of all evil' was that the gun design and development though to Admiralty requirements was in the hands of commercial firms, while the ship design was done by the Royal Corps of Naval Constructors reporting to Admiralty committees. The latter had to adapt ship layout to accommodate the specified armament. KGV's whole citadel was moved forward about 6ft to deal with the changes in trim due to the lighter twin turret.