The original design called for a seaplane and crane between the funnels. This was replaced by two quad 2pdr pompoms in order to augment AA defence. Two triple
torpedo mounts were also added. For surface targeting, a Mk IV director was installed on the bridge. Two high angle directors for AA fire were fitted, one above the
bridge and one aft of the mainmast, giving the ability to engage two aircraft simultaneously. The after HA director was dual purpose as it could also be used to engage
surface targets. The unit system of machinery was chosen with alternating boiler and engine rooms. A quadruple screw arrangement would drive the ships at 33 knots
at 62,000 SHP and endurance was 5,000 nm at 16 knots. Four turbo-generators capable of generating 1,200 Kwh were also installed. The armour scheme consisted
of a 3” belt abreast the engineering spaces with a 1” deck and transverse bulkheads at the ends. A 2” platform deck covered the magazines which also had 1”
longitudinal bulkheads fitted abreast. The turrets had 1” to 1.5” plate and the steering gear was enclosed with 1” sides and deck. This scheme was deemed sufficient
to deal with 6” gun fire. As much weight saving as possible was incorporated: welding of the forward sections, a reduced number of shells, copper piping, no
handing room between the magazines and turrets, no spare gun barrels carried aboard, and lighter High Angle directors. The Mk II 5.25” mounting was chosen as it
featured combined magazines and shell rooms, saving weight and offering a reduction of some 60 crew members, no small consideration given the small size of the
ships. The following ships were ordered: Five in 1936: Dido, Euryalus, Naiad, Phoebe, Sirius: Two in 1937: Bonaventure, Hermione: Three in 1938: Charybdis,
Cleopatra, Scylla: Six in 1939: Argonaut, Bellona, Black Prince, Diadem, Royalist, Spartan. This was the largest cruiser program since the First World War. The
class would be split into three groups: Dido, Euryalus, Naiad, Phoebe, Sirius, Bonaventure, Hermione, Cleopatra, and Argonaut built to the original design;
Charybdis and Scylla armed with 4.5” guns; Bellona, Black Prince, Diadem, Royalist, and Spartan of a modified design with 4-5.25” turrets. By 1939, none were
ready due to bottlenecks with turrets, fire control equipment, turbines, and reduction gearing although the first ten had been laid down and six had been launched. In
the spring of 1939, with Bonaventure about a year away from completion, a problem of supply of the 5.25” mounts arose as they had also been chosen as the
secondary armament of the King George V class with the battleships having priority.
Compounding the problem was the pending order for five ships of the 1939 program. Partly as a result of the shortage of turrets and partly as a compromise to free up
additional mountings and allow a sixth ship to be ordered in 1939, it was decided to complete Charybdis and Scylla with 4.5” guns instead. Known derogatorily, ‘The
Toothless Terrors’, Charybdis and Scylla were in fact true anti-aircraft cruisers. Despite these measures, three of the first four to complete were one turret short:
Bonaventure, Dido, and Phoebe, each mounting single 4” star shell gun instead. Bonaventure carried hers in ‘X’ position; Dido and Phoebe in ‘Q’. Dido would
eventually receive her 5th turret, Phoebe never would, and Bonaventure would be lost before she received her 5th turret. All the remaining ships completed with the
full outfit of turrets. Construction of the six ships of the 1939 group was suspended in 1940. All were subsequently restarted, but only Argonaut was completed to
the original design. The other five were completed to the modified design featuring only 4-5.25” twin mounts, a lower bridge, and straight funnels and masts. Of the
original group, Bonaventure was the first to complete in May 1940; Argonaut was the last in August 1942. The second group completed from August 1943 (Spartan)
to January 1944 (Diadem). All of the ships completed with some form of radar, and by 1943 surviving ships all had types 272, 281, 282, 284, and 285 installed. As
first of type, Bonaventure was subject to extensive trials, complicated by troubles with the 5.25” mounts which took Vickers 3 weeks to correct. In all other respects
the ship was deemed satisfactory. Bonaventure suffered weather damage in November 1940 which buckled two pillars under the forward deck; this was solved by
additional stiffening. Naiad had movement in the deck and bridge which caused leaking; deck movement in other ships resulted in frequent jamming of ‘A’ turret.
It was determined that most damage was caused by driving them too hard in bad weather. As experience was gained during operations, crews were able to allow for
adverse weather conditions with the result that no further weather damage was reported. Overall, the ships were good sea boats but prone to heavy pitching, mainly
due to the heavily loaded ends. They were less successful in the AA role than the 4” armed C’ class, mainly due to the heavy and slow 5.25” gun mount.
Many modifications were made to the close range AA armament during the war, references and photographs should be consulted. Camouflage schemes also varied
considerably, references should be checked carefully. They were used extensively mainly in the Mediterranean where they gave good service in the face of constant air
and submarine attack. Five of them were sunk, four to torpedoes in the machinery spaces: Naiad, Bonaventure, Hermione, and Charybdis. With the lack of reserve
buoyancy on such a small hull it is not surprising that flooding in the large machinery spaces would cause the loss of the ship. Spartan was lost after being hit by a
glider bomb. In addition 6 of the ships were very heavily damaged from bombs, torpedoes, or shellfire. Phoebe and Argonaut were torpedoed twice and Cleopatra
once, Cleopatra managing to survive a torpedo hit in the machinery spaces. Phoebe and Argonaut were fortunately (!) hit elsewhere on the hull. Scylla was not fully
repaired after being mined off Normandy. Dido and Sirius were both heavily damaged by bomb hits. Cleopatra was also damaged by bombs and a 6” shell hit from
the Italian battleship Littorio.
|
|
