Читать книгу The Gathering Storm - Geirr Haarr - Страница 17

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Contact Obtained

Echoes

AT THE END OF WWI, the British Navy had developed a prototype for active underwater sonar-based submarine detection gear, the so-called Asdic.¹ By 1923, the 6th Destroyer Flotilla operated several Asdic-equipped vessels on a regular basis. The following year, the Anti-Submarine Warfare School, HMS Osprey, was established at Weymouth and a training flotilla of four vessels set up at Portland.

Asdic works by sending a narrow, ultrasonic sound wave, created by an oscillator, through the water. When it strikes anything, including the hull of a submerged submarine, an echo is bounced back that can be picked up by a hydrophone in the A/S vessel. The transmitter and receiver were usually housed inside a dome fastened to the outside or lowered by an electric motor through an opening in the bottom of the ship’s hull. That was usually no problem at sea, but vulnerable to damage in shallow, coastal waters. On board, the echo was recorded as electrical impulses heard by the operator and displayed on a screen or as marks made by a stylus on a paper roll. The hydrophones of 1939 could determine the direction of the echo quite accurately. The distance to, and hence the depth of, the object giving the echo was not given, though.

The Asdic operator, sitting in a small cabin near the bridge of the A/S vessel, operated the equipment via a wheel, sweeping the Asdic beam around the ship, searching for echoes. Submerged submarines could be detected at a distance of up to 2,700 yards. So too would wrecks, schools of fish and anomalies in the water column, and it would take an experienced operator to know what he had in his beam. In reality, a U-boat had to be within 1,600 yards to be firmly ascertained, and even closer if it was end-on. When an echo was established, its bearing was forwarded to the captain via the Asdic officer in charge, including an estimated distance to the object based on the strength of the echo. If possible, positive or negative Doppler effect was added, indicating an increase or decrease in the frequency of the echo, signifying if the A/S vessel and the U-boat were closing or moving away from each other. By September 1939, four different Asdic sets for various types of surface vessels had been developed, as well as one for submarines. Some 180 vessels were fitted with Asdic. Of these, 150 were destroyers, twenty-four were sloops and six were other types of patrol vessels.²

A/S warfare was considered tedious before the war and limited attention was paid to training the officers and commanders to understand what the instruments told them and how to use the information tactically. There was a delicate chain from the Asdic operator to the captain and his team on the bridge, and from them to the depth-charge operators on deck. Unless all elements of this chain were fine tuned and aware of their dependence on the others, day and night and in all kinds of weather, the weapon system was less than fully efficient. Knowing where the U-boat was, even if detected by the Asdic, was far from easy and required quick three-dimensional thinking by the captain – all the more so as the Asdic lost contact as the escort increased speed, closing the distance to deliver the attack. In difficult Asdic conditions, or when the water was disturbed by multiple depth-charge explosions, the chance of a U-boat escaping a single A/S vessel was relatively good.

The use of several ships in cooperation, one keeping Asdic contact while the others attacked, increased the efficiency of the A/S vessels significantly, but was a tactic that also had to be learned and exercised.

Few in the Royal Navy were proficient in A/S warfare in 1939, and when the ranks swelled with a large number of RNVR, draftees and volunteers, the overall competence did not increase. Intense practice was needed, not least on the after deck where reloading of the depth-charge throwers was found to be disturbingly slow.³

Hardly any Asdic exercises had been conducted under conditions close to reality. In the exercises that were held, it was often found that the Asdic failed and even when it did work, it had a number of weaknesses. British submarine captains found it relatively easy to escape Asdic-equipped destroyers, once they learned how the apparatus worked and how the A/S crews responded to the information it gave them.⁴

By overestimating the efficiency of Asdic and not appreciating its deficiencies and the need for adequate training, the Admiralty to a large degree predestined the Royal Navy to start the war with a severe handicap. The fact that some U-boats were sunk seemed to confirm the belief of the Admiralty that a convoy system backed up by Asdic, aerial reconnaissance and more effective depth-charges would all but neutralise the submarine threat. That the sinkings were significantly overrated and that most U-boats actually got away was dismissed, as was the fact that most of the Asdic sets were fitted in destroyers intended for fleet-work and not convoy escort. Likewise, it was not appreciated that surface attacks at night would render both Asdic and aircraft useless. Few believed at this stage that high-quality radar and radio direction finding would be as important as Asdic in overall convoy protection.⁵

On 20 September, destroyers Imogen and Ilex were patrolling south-west of Land’s End under the command of Commander Henry Pawsey on board Keith. Lieutenant Robert Ewing was first officer of Imogen. His diary is revealing of the confidence some officers carried regarding their ability to defeat the U-boats:

At 7.20 p.m. we received from Flying Boat: ‘Am over enemy submarine in pos. 49° 42' N, 07° 25' W. Keith made to Ilex: ‘[Will] proceed to search for S/M on or near surface. Patrol independently during the night to eastward of 8° 30' W, rejoining me in 49° N, 9° W. Why in God’s name he did not take all of us to search I cannot understand. We were doing nothing in particular and sending one destroyer to find a submarine after half an hour’s delay is fantastic. [. . .] He is obviously out of touch with things. [. . .] Keith reaped his reward from C-in-C Western Approaches in the following: ‘When report of U-boat is definite, your whole force should be sent and remain until she is destroyed.’⁶

C-in-C Western Approaches Admiral Martin Dunbar-Nasmith was one of the first to realise the deficiencies of the A/S systems, and he issued a series of instructions on 25 September to the Anti-Submarine Striking Forces operating under his command. It was essential to sink U-boats and kill or capture German submariners. One of the paragraphs read:

When contact is obtained, the U-boat is to be hunted continuously and relentlessly until destroyed. Should contact be lost, the search is to be continued day and night until is regained. No contact is ever to be relinquished until it is considered certain that the U-boat has been destroyed, or it has been established the contact was a ‘non-sub’.⁷

Whenever an attack on a U-boat was reported it was assessed by a committee of the Anti-Submarine Warfare Division and given an official status as sunk, damaged or even ‘non-submarine’ at times. The NID made aggregated valuations based on these assessments and independent information available to them. Surprisingly, this created a serious contention between NID and the First Lord, with Churchill wishing to announce measures of success while NID saw the need for an accurate assessment as the basis for tactical and operational amendments. Still, even NID overestimated the number of U-boats actually sunk. At the end of 1939, Churchil implied that some forty U-boats had been sunk so far in the war, NID held a maximum of twenty-five, while the actual number was nine. By 10 March 1940, NID estimated a maximum of twenty-one sunk versus the actual number of sixteen (see Appendix G).

At the beginning of the war, the only A/S weapon available to the Royal Navy was the depth-charge. This was little more than a free-sinking cylindrical container filled with around 330 pounds of high explosive, originally Amatol, later changed to Minol, a mixture of TNT, ammonium nitrate and powdered aluminium, which had a greater explosive effect for the same weight and volume.⁸ The depth-charges were detonated by a firing pistol activated by hydrostatic pressure with fixed settings at fifty-foot intervals from 50 to 500 feet (15–150 metres).

The Royal Navy Type D Mark VII depth-charge, which was standard by 1939, had an initial sinking speed of 2 metres (6 feet 6 inches) per second, increasing to 3 metres (10 feet) per second at depth. Improved sinking rates were obtained by adding cast-iron weights to the charges. When it was realised that the U-boats went deeper than expected, improved hydrostatic triggers later also increased the maximum triggering depth. In theory, if the charge exploded within 15–25 feet from the hull of a U-boat, the submarine would be destroyed. At more than twice that distance, damage could still be significant, often forcing the boat to surface.

Usually, the depth-charges were dropped in a pattern of five if a U-boat had been identified. Three were dropped or rolled from the stern in succession, some 150 feet apart, while two were fired from depth-charge throwers, one on each side amidships, to a distance of 150 feet from the ship. These two were timed to hit the water at the same time as charge number two was dropped from the stern. The T-shaped depth-charge holders were manhandled into the throwers, whereafter the charges were set in place by a block and tackle. It was hard work, which meant that time was needed to prepare each attack. Not all trawlers or auxiliaries had depth-charge throwers installed from the start.

Pink Gin

There is no doubt that the failure of the Admiralty to accept the need for and provide adequate numbers of suitable escort vessels with satisfactory A/S capacity in terms of Asdic, weapon systems, tactics and training in time, was a serious blunder. With the exception of a limited number of multi-purpose sloops, no A/S escort vessels were built by the Royal Navy between the two wars; the destroyers were built for a different purpose, with A/S capacity as, at best, a secondary task.

Depth-charge ready for action on board the destroyer Ardent. The cylinder on top of steering-guide is the explosion chamber, set off by the rope attached to the firing wedge and pistol on its top. (M Sellick collection)

The explosive effects on the surface were also huge and the A/S vessels frequently suffered damage. (Author’s collection)

Having been deployed singly or in small groups at overseas stations around the world, a number of the sloops were called back to Britain during 1939. Most of them needed a spell in the yards before being assigned to convoy escort and when deployed, as with the corvettes later, they were found unsuitable for sustained work in the Atlantic under winter conditions. The Hunt-class destroyers, designed during 1938 in an attempt to provide a seagoing escort for both warships and convoys, were few in numbers due to yard capacity and they did not really stand up to sustained deep-sea convoy work during the winter season either. Smaller vessels, motor torpedo boats (MTBs) and motor gunboats (MGBs), to protect coastal convoys from surface or air attacks were not on the agenda of the Admiralty until the war had already started and it would take a long time before these were effectively operational.

During the summer of 1939, the Admiralty commenced requisitioning the first of around 400 trawlers and drifters between 200 and 600 tons for a rebuild of the auxiliary fleet. Half of the vessels would be equipped for A/S duties, the rest for mine-sweeping. By the end of the summer, eighty-seven ships were acquired, twenty of them directly from the yards.⁹

As the outbreak of war approached, further ships in every fishing port around Britain were taken over as they returned from the fishing grounds. Nets, warps and tackle were stowed away on land while the fish-holds, still smelling of the last catch, were turned into mess decks. Then trucks arrived with floats, otters, kites, wires and a multitude of crates. A 4-inch gun, or sometimes a 12-pounder, was mounted on the foredeck, usually after a strengthening of hull frames and deck beams. One or two 20-mm Oerlikon or Bofors guns aft of the funnel, a couple of Lewis or Hotchkiss machine guns in the bridge wings for close A/A defence and a few rifles for destruction of drifting mines completed the armoury. On top of most trawlers’ bridge houses an open enclosure was set up, known as ‘mount misery’, complete with a sheltered chart table, master compass and voice-pipes. Confusion reigned, but somehow most ships had rigged their gear and were ready for war within a couple of days. Royal Naval Reservist Sidney Kerslake, a fisherman with four-and-a-half years’ experience of northern waters, was called to the Royal Naval Patrol Service (RNPS) at Lowestoft and was eventually posted on board the trawler Northern Gem:

On 17th September 1939 I found myself on a train with the rest of the crew, bound for Barrow-in-Furness, to join His Majesty’s Ship 194. It turned out to be the armed escort trawler, Northern Gem, which I had seen several times before the declaration of war, on the northern fishing grounds of Iceland, Bear Island, the Spitzbergen grounds, and the Barents Sea. [. . .] Our first glance around the Gem gave us a picture of complete shambles. Everything seemed to be in pieces, with gear of all shapes and sizes lying about all over the place, decks were cluttered up as were the alleyways, the compartments and the engine room. I believe the only compartment that hadn’t been turned out was the crews’ quarters. [. . .] The armaments consisted of one 4-inch quick firing gun of WWI vintage, set on a platform just above the after end of the whaleback, and behind the windlass which was used for hauling in the anchor, or in some cases hauling the ship alongside the quay by means of the head rope. Amidships, on either side of the Skipper’s cabin, was a sort of half round platform on each of which there was situated a twin Lewis gun. Further aft and actually on top of the galley and in between both the port and starboard lifeboats there was another twin Lewis gun. Apart from the depth-charge rails right in the stern, and the single depth-charge thrower on the deck at each side of the galley. [. . .] nothing much had changed since she had fished. [. . .] The crew consisted of a skipper lieutenant, a coxswain, a leading hand, four or five seamen, a chief and second engineer, two firemen or stokers, a cook and a gunner. [. . .] The flotilla [consisted of] the Northern Dawn, the Northern Wave, the Northern Spray, and the Northern Pride.¹⁰

A/S trawler Northern Gem. Northern Gem and her Northern sisters had been built in Germany in 1935 as reparation of debt. They were fine ships, larger than the ordinary British fishing vessels. (E Skjold collection)

Once fitted out and painted in Admiralty grey at local yards and workshops, the smaller and older ships were bundled into mine-sweeping flotillas, four to six in each group. Some of these groups were supplemented by requisitioned paddle steamers, ideal in draught and speed, but only suitable for fine weather, near-shore work. The larger and more modern trawlers received Asdic and depth-charge tackle to fight U-boats.

More often than not, most of the original crew of the drafted boats were kept, while a few navy officers were added, together with weapons specialists and signals staff. Some of the sailors were RNR and had varying amounts of training, others had none. Around 230 trawler skippers had received peacetime training in the handling and use of sweeping gear, as had a handful of RNVR yachtsmen. For these, and other qualified men holding a Board of Trade Certificate of Competency, the special rank of skipper RNR was instituted, equivalent to warrant officer RN. Most ships had an RN officer as commander and a RNR skipper as first officer, but in some a senior RNR skipper acted as commander as well.¹¹ Group leaders were generally RN officers. Retired officers with experience of sweeping were recalled and, after a quick refresher course appointed as port minesweeping officers or commanders of the new mine-sweeping flotillas. By the end of the year, a total of 582 ships, mostly trawlers, drifters and yachts, had been requisitioned for mine-sweeping. An area outside Lowestoft, known as HMS Europa, or more commonly as Sparrow’s Nest, was chosen as a suitable assembly point, depot and headquarters for the rapidly increasing fleet of what was now known as the Royal Naval Patrol Service.¹²

By February 1940, most trained personnel of the RNR and RNVR had been mobilised and the ‘hostilities only’ personnel started to come in. These were eager enough, but lacked pre-war training and needed a longer time to become functional. In all, 1,921 ships had been requisitioned by 31 December 1939. By April 1940, this had risen to 2,199. Besides mine-sweeping, convoy escort and A/S work, most of the vessels were deployed for harbour protection, contraband control or transportation. A handful of the larger trawlers were assigned as armed boarding vessels (ABVs) operating with the Northern Patrol.¹³

The quantity of new sailors and officers, many with significant experience from years at sea, opened up a number of unforeseen challenges where discipline and standards of ‘spit and polish’ were somewhat different than in the peacetime Royal Navy. As the auxiliary services were rather unglamorous, the officers tended to be junior, and many young RN lieutenants found it hard to handle seamen twice their age and used to a rough life. Hence, many older RNR or RNVR officers, often from a long life at sea themselves, were sent to the little ships. Discipline, language and uniforms often horrified the career officers on cruisers and destroyers. Having a little ship up front, with sweeps out, was always welcome, though, unless it was a ‘Smokey Joe’ with bad coal, seen from miles over the horizon.

One unit equipped with trawlers was the 15th A/S Striking Force, working off Scotland in the autumn of 1939. Its rather flamboyant commanding officer was Lieutenant Commander Martyn Butt Sherwood on board Cape Pesaro. Lieutenant Colin Warwick reported on board in early September, having been told that Sherwood had requested his RNVR lieutenant to be replaced forthwith by a RNR officer with some experience.¹⁴ Warwick later wrote:

Over a pink gin, Sherwood commented that his crew of Hull, Grimsby and Fleetwood deep-sea trawlermen seemed a little ‘mutinous’ regarding his RNVR No. 1’s handling, saying ‘He screams at them and they fart back at him!’ [. . .] Rogers, the Coxswain, told me that my predecessor had refused to handle a problem regarding lice or ‘crabs’ with which most of the seamen had become infected by their female contacts in Hull. ‘Have all the seamen shave off their body hair and dispose of it, and we will see the base doctor about getting some blue ointment to rub on their personal parts,’ I told Rogers.¹⁵

After some direct communication with the ‘lads’ in a language they understood, including how the King’s Rules & Regulation and the Admiralty Instructions were to be applied on board, Lieutenant Warwick got a firm grip on the mess deck and the war could commence. Besides Cape Pesaro, the 15th A/S Striking Force consisted of St Goran, commanded by Lieutenant Commander William McGuigan, St Kenan with Lieutenant Jimmy James and St Loman with Lieutenant John Cambridge.¹⁶

Rating Bardsley operating the double .303 Lewis gun on board Northern Spray. (E Skjold collection)

These ships were newbuilds taken over by the Admiralty straight from the builder’s yard or only a few years old. They were armed with one 4-inch gun, two or three machine guns (MGs) and forty to fifty depth-charges. The crew had ‘adequate conditions but lacking in comfort’. The mess decks and sleeping quarters for the seamen and stokers were in the converted holds below the foredeck. The officers’ wardroom and cabins, usually shared, were further aft. The only place with some comfort was the skipper’s cabin, as a result of the trawler companies trying to attract the best of those, before the war.

Joining them in Aberdeen were also the 16th A/S Striking Force led by the no less flamboyant Lieutenant Commander Geoffrey Congreve in Aston Villa and accompanied by Arab, Angle and Gaul. Their patrol area was the North-Western Approaches and the entrance to Scapa Flow. To ease the burden on the men of the small ships, Sherwood and Congreve used their old networks and obtained permission to keep Aberdeen as home port while using Scapa Flow as the operational base. For the seamen and officers this meant a most welcome spell in Aberdeen for boiler cleaning and maintenance every five to six weeks and a more varied entertainment ashore.¹⁷

In spite of high expectations, the results of the A/S Striking Forces during the first winter of the war were rather meagre. Few U-boats were intercepted and most of the patrols were routine, fighting the weather more than the Germans. Only on one occasion in February was a contact gained and depth-charges dropped. Oil came to the surface and the contact vanished, but no U-boats were lost or damaged in the area at the time so it might not have been a U-boat at all.

It would be quite some time before the Royal Navy realised that finding a lone U-boat in deep waters was extremely difficult, basically down to serendipity, and that resources would be better spent protecting convoys.

The Kriegsmarine also employed trawlers extensively for numerous tasks. This is V404 Gebrüder Kähler in the autumn of 1938 off Bremerhaven. (Author’s collection)