Abdiel-class minelayer

The Abdiel class were a class of six fast minelayers commissioned into the Royal Navy and active during the Second World War. They were also known as the Manxman class and as "mine-laying cruisers". These ships were armed with a wide variety of defensive weapons from 0.5 in machine guns to the 4 in main armament. They were also equipped with a wide array of radars, along with their normal complement of mines. They were easily mistaken for destroyers. Half the class was lost through enemy action during the Second World War; the others saw post-war service, and the last example was scrapped in the early 1970s.

Design
The Royal Navy ordered the first four ships in 1938, with a further two acquired as part of the War Emergency Programme. They were specifically designed for the rapid laying of minefields in enemy waters, close to harbours or sea lanes. As such they were required to be very fast and to possess sufficient anti-aircraft weaponry to defend themselves if discovered by enemy aircraft. A large load of up to 150 mines was required to be carried under cover, therefore a long, flushdecked hull with high freeboard was required. The mines were laid through doors in the stern; the ships carried their own cranes for loading.

In size these ships were almost as long as a cruiser but laid out much like a large destroyer except for the three straight funnels, which were an instant identifying feature. Top speed was specified as 40 kn. To achieve this they were given a full cruiser set of machinery and with an installed output of 72000 shp on two shafts, they made 39.75 kn light and 38 kn deep load. To put this into perspective, the contemporary Town-class cruisers had 80000 shp and a full load displacement of 12,980 tons, just short of four times that of the Abdiels.

The ships were initially to be armed much as destroyers, with three twin HA/LA Mark XIX mounts for QF 4 in L/45 Mark XIV guns, with an elevation of 70°, in 'A', 'B' and 'X' positions, a quadruple "multiple pom-pom" mounting Mark VIII for the QF 2-pounder Mark VIII and a pair of quadruple 0.5-inch Vickers machine guns.

Wartime modifications involved adding a Type 279 radar at the masthead, a primitive metric wavelength air warning set, later replaced by a Type 286 then a Type 291, as they became available. A Type 285 radar was fitted to the rangefinder-director on the bridge, this was a metric set and could provide target ranging and bearing information. The centimetric Type 272, a target indication radar with plan position indicator (PPI), was fitted to the front leg of the foremast. Following the loss of Latona to air attack, the surviving ships were re-armed to remedy the shortcomings in anti-aircraft defence. Six single Oerlikon 20 mm cannons were initially added on P Mark III pedestal mountings, although these were later replaced by powered twin Mark V mountings. Ariadne and Apollo had two twin Mark IV "Hazemeyer" mountings for Bofors 40 mm guns sited amidships, replacing the pom-pom in 'Q' position, and these mounts carried their own Type 282 Radar for target ranging; Ariadne had an additional "Hazemeyer" mounting in 'B' position, replacing the 4-inch guns. In July 1945, Ariadne was refitted in the United States for far eastern service, when the Bofors mounts were replaced by American pattern models (Mark I) with off-mounting "simple tachymetric directors" (STD) fitted with Type 282 Radar and the Oerlikon mounts re-gunned with Bofors guns (this combination was known as the "Boffin").

While generally a successful design, these ships suffered from two fundamental problems. The first was their low endurance. Designed for an endurance of 5300 mi at 15 kn after six months out of dock, sea trials showed 4680 mi to be a more realistic estimate and this endurance dropped sharply at high speeds. This limited their ability to deploy even in the constricted waters of the Mediterranean Sea to the point that Admiral Cunningham recommended that ships still under construction be fitted with additional fuel tanks, which was done for the last two vessels. The second problem lay in their vulnerability to damage. They had no armour protection or anti-torpedo bulges and their large machinery spaces and large, undivided mining deck limited their internal compartmentalization, which left them vulnerable to flooding.

Service
Although they were effective ships in their intended role, the combination of high internal capacity and exceptionally high speed meant that they were equally valuable as fast transports. As such, for much of their service, they were used for running supplies, particularly men and matériel, to isolated garrisons such as during the Siege of Tobruk and Malta in Operation Harpoon. With three funnels and the outline of a destroyer, HMS Welshman (M84) was camouflaged to appear like the Vichy French contre torpilleur (large destroyer) FRENCH DESTROYER Tigre. For this, a false bow was fitted, funnel caps were added, the mine chutes were plated over and a false deckline was painted on to camouflage the high flush deck. Manxman received a similar disguise to pass for the Vichy contre torpilleur FRENCH DESTROYER Léopard so she could pass Corsica and mine the approaches to Livorno.

On 25 October 1941, Latona was hit by a 250 lb bomb in the engine room, causing a serious fire that spread to the munitions she was carrying and resulting in her loss. Welshman was torpedoed and sunk by GS U-617 in 1943. Manxman was torpedoed in her engine room but survived, although repairs took two years.

Apollo, Ariadne and Manxman survived the war and saw post-war service, with their pennant numbers changed from "M" to "N". Apollo served as a despatch vessel and Manxman as a mine warfare support ship. In 1953, Manxman was used to depict a German raider in the re-made film of C. S. Forester's novel Brown on Resolution; for this her funnels were enlarged to alter her outline, dummy 6-inch barrels were fitted over her 4-inch guns, and her bow was painted to indicate 'torpedo damage'.