two mining doors at the stern. The fast minelayers were fitted with the ‘chain conveyor’ system for moving the mines around and laying them, with the older ‘wire and bogie’ system as a backup.
A profile of the final design of the Abdiel class. (Eric Leon)
To facilitate their minelaying operations, the Abdiels were equipped with taut wire measuring gear, which fulfilled the very important function of allowing the positions of their minefields to be assessed with greater accuracy. The gear was first designed for ships laying submarine telegraph cables and consisted of ‘in simple terms a long length of piano wire paid out astern of the minelayer, the amount of wire run off being measured with a high degree of accuracy and recorded on a form of cyclometer’.10 It would prove to be a vital tool for the fast minelayers, when it worked.
The Abdiels’ capacious mining deck was a salient feature of the ships, designed for mines weighing 1¼ tons to run on a ‘Clapham Junction’ network of rails. The ships were equipped with two large cranes, one to port and another to starboard. A post-war history of the Navy’s Construction Department recognised that the fast minelayers were often used for carrying stores and naively claimed that the stores carried on the mining deck were limited to 200 tons.11 That may have been the official policy, but someone must have neglected to tell the Construction Department that in practice the Abdiels carried at much as 373 tons of stores and equipment on the mining deck.12
The ships were unarmoured, with only 10lb protective plating on the bridge. Their hulls were too small for any special protection against torpedoes, other than their normal compartmentation, which unfortunately featured fairly large machinery spaces prone to flooding over a large area with a single torpedo. In hindsight, the bigger problem was their large, undivided mining deck, which did not improve their chances of survival in the event of flooding.
The Abdiel s’ accommodation was to be that of a cruiser or above and their designed complement was twelve officers and 224 men; in practice they accommodated more, by one count 260.13 They were also capable of carrying many passengers and sometimes carried ‘special’ ones, such as brass hats, wounded men and POWs. Their designed complement of boats included a 25ft motor cutter and a 14ft sailing dinghy to port, a 27ft whaler and a 25ft motor boat to starboard, and a 16ft planing dinghy atop the after deckhouse.
The heart of the design of the fast minelayers was, naturally, their machinery. The design provided for four boilers with a working pressure of 300lb/sq. in. at 200° F superheat, divided between two boiler rooms, No 1 forward of No 2, with one boiler in each compartment trunked into the middle funnel. They sported two sets of single-reduction geared turbines – high-power, low-power and cruising turbines – in a single engine room, with the associated gearing in a gearing room immediately aft of the engine room. The turbines drove two shafts and two propellers, each of which had a diameter of 11½ft. Each boiler was designed to develop 18,000 SHP at 350 revolutions per minute, for a total of 72,000 SHP, exactly double that of the Abdiel of the First World War and more than any destroyer in the Royal Navy at the time; the ‘Tribal’ class destroyers developed 44,000 SHP.14 The Abdiels’ designed maximum speed was 39.5 knots at 350 revolutions.
However, the Abdiel s’ true maximum speed soon became the stuff of exaggeration, if not legend. One former crewman claimed with complete earnestness and sincerity to have been shown his ship was making 50 knots. The controversy over their true speed has persisted at least as late as 2012, in the pages of the Navy News, where a claimed speed of 44 knots prompted some spirited debate. The fact is that while the Abdiels were very fast ships, they could not defy the laws of physics. Their design was original but not obviously innovative, especially since they lacked a secret such as superheated boilers; they simply packed very powerful machinery into a small hull with just two shafts and propellers. If there was secret to their speed, it was that they packed more power on each shaft (36,000 SHP) than any other British warship15 besides the battlecruiser Hood, which was also designed to develop 36,000 horsepower on each of her (four) shafts.16
In any case, they were without a doubt the fastest ships in the Royal Navy and may have made just over 40 knots. The Welshman made 37.6 knots on trials,17 and on her trials the Manxman made 35.6 knots while developing 73,000 SHP.18 After her refit in 1942, the Abdiel made 38.6 knots, according to her Navigator, Lieutenant Alastair Robertson, who took great care to measure her speed. For the sake of comparison, the highest speed a major British warship ever made on trials was the 39.4 knots made by the Yarrow ‘S’ class destroyer HMS Tyrian in 1919, though she was in a light condition and with ‘very highly stressed machinery’. In service, she could probably make 36 knots with a clean bottom.19
More importantly, again and again the Abdiels proved that they could maintain high speed in real sea conditions. Almost as important, they could do so without excessive vibration, which would have hindered their effectiveness. A downside to great speed was that, at least early in the Abdiel’s first commission, it led to cavitation, erosion of the base of the propellers. The propellers had to be replaced, but for a time she had to limit her speed to 25 knots.20
The Abdiels were faster than any ship in the US Navy and were equalled or outstripped by very few ships of other navies. For speed, the Abdiel s’ competitors were the six French super-destroyers of the Fantasque class (2569 tons, up to 45.02 knots on trials), the French super-destroyers Volta and Mogador (2994 tons, up to 43.78 knots on trials),21 the Italian-built Soviet destroyer leader Tashkent (2893 tons, rated at 110,000 SHP and 42 knots),22 the three Italian small light cruisers of the ‘Capitani Romani’ class (3747 tons, up to more than 43 knots),23 and the Japanese large destroyer Shimakaze, which was about the size of an Abdiel, at 2567 tons, and made as much as 40.7 knots at 79,240 SHP during her short life, but she also sported boilers that operated at an extremely high temperature (400° C) and pressure (571 psi).24 Not to take away anything from these ships, but they were not nearly as versatile as an Abdiel, though the Tashkent was used a fast transport during the siege of Sevastopol in 194225 before she was damaged at sea and then sunk at the quayside by German dive bombers.
The speed of the Abdiels was one thing, but their endurance was a very different matter. The Abdiels were designed to store 591 tons of oil fuel and 58 tons of diesel fuel, which was primarily for their generators but could be used in the boilers as well. They were to have an endurance of 5300 to 5500 miles at 15 knots when six months out of dock (and with a correspondingly barnacled bottom), but it was estimated from their sea trials that their endurance was only 4680 miles under those conditions. With a clean bottom, their endurance was estimated at 5810 miles.26 In 1942, based on experience with the Manxman, the Admiralty estimated their endurance as 3300 miles at 20 knots, 2070 miles at 25 knots, 1450 miles at 30 knots, 1060 miles at 35 knots and only 845 miles at their maximum speed of 38 knots.27
The Abdiel s’ limited endurance was to become a real concern and was the Achilles’ heel of the design. This unfortunate trait was to some extent rectified in the Repeat Abdiel s. In not living up to their designed endurance, the Abdiels were hardly unique among British warships of the Second World War; according to a Royal Navy study, British warships entered the war with machinery that was 25 per cent less economical than that used in the US Navy.28 Another class that disappointed in this regard was no less than the King George V class battleships. Their fuel consumption under trials conditions was 2.4tons/hr at 10 knots, but in practice it was 6.5 tons/hr, due to heavy consumption by auxiliaries and steam leaks. In 1942, it was found that the true endurance of the new American battleship Washington was double that of a KGV.29 During the Bismarck chase, both the King George V
