Alphabet Soup 2 – Battlecruisers
Battlecruiser concepts also started with what designers knew and understood; the Royal Navy’s latest and best all-round ship, HMS
Rodney, herself a derivative of
Hood.
They got off to a flying start with the ‘C-series’, which used an expanded version of the hull form of
Hood with a transom stern to maximise available length.
These were effectively ‘Super Furious’ designs
, which removed many of the deficiencies of the original ship. The hull was deeper and stronger, and a uniform 12" belt reached the upper deck, which would have 4-5" of armour.
Furious’ bizarre turbine arrangements and numerous boilers were replaced with the machinery of
Hood, slightly improved to deliver 140,000shp.
At 875' x 106', C-2 was a flush-decked, transom-sterned ship with eight 18” Mk.1 guns in four turrets. Turret protection was improved to match that of
Rodney, with 15” faces and 5” roofs, but the twelve 6” in shielded mounts were as in earlier ships. Displacement was 48,500 tons (normal), and speed would be 30 knots.
C-3 had nine 18” Mk.1 in three turrets. Displacement decreased to 47,900 tons, but speed would still be 30 knots.
Royal Navy commanders salivated when they saw these concepts, but as ever the devil was in the details, and the designers never regarded the C-series as more than a baseline. It did highlight several issues; that nine guns in triple turrets could be provided for virtually the same weight as eight in twin turrets, and that (as
Rodney's designers had found) the Admiral-class hull form and machinery was being pushed to its limits.
The ‘D-series’ could be regarded as hybrids of
Hood and
Rodney, and were the last of the Admiral-class derivatives. With transom sterns, length was 860' and beam 106', with an armament of 16" Mk.2 guns.
D-2 was simply modernised and stretched version of
Rodney, with the hull altered to allow a full set of improved
Hood machinery to be fitted, and to give a slightly deeper torpedo bulge (thereby increasing its effectiveness). Overall weight of armour was slightly less than
Rodney, but it was better distributed, as deck armour would consist of a single thickness of 3-5” on the upper deck, while protection to the ends of the ship was virtually eliminated. However, the changes were something of a disappointment, as models showed that 140,000shp was expected to deliver only 31 knots at a normal load of 43,100 tons.
D-3 had nine 16", with the barbettes for the triple turrets being better protected than on the original twins. At 43,600 tons, speed was perhaps a tenth of a knot less than D-2, but this still counted against them.
Neither ‘C’ nor ‘D’ could be regarded as entirely satisfactory. Deck armour had been made more effective, but not more extensive, and all the designs had the same 12”, 10-degree inclined belt as
Rodney. Torpedo protection was only slightly improved, and at realistic seagoing loads, it was unlikely that the C-series would achieve more than 29 knots.
It was known that the Americans were building their ‘Lexingtons’ with a speed of at least 32 knots, and the Japanese were certainly designing 30-knot or 32-knot battlecruisers. Aside from this immediate concern, a further factor was that these ships would be required for a great deal more than eight years of front-line service. In an era of larger ships and post-war austerity, this new generation of capital ships would be expected to serve fifteen or more years in the front line.
Once those facts sunk in, it was believed that ‘C’ and ‘D’, although impressive, would be too slow to be competitive battlecruisers into the 1940s.
However, some months later, the series was revisited with D-33, although she was in fact an entirely new ship, derived from the hull form and improved machinery of the later ‘I-series’, but with a more conventional layout. Power was increased to 160,000shp, displacement to 45,500 tons and speed to 32¼ knots. Protection was also improved, in the form of an internal 12” inclined belt, with six new twin turrets for the 6” battery.
