Trying To Stay Ahead Of The Pack

May 24, 2013 by Marc Milner

The failure to stem the U-boat assault in the St. Lawrence was an embarrassment to the Royal Canadian Navy and the government in 1942. Indeed, it was the clearest manifestation that Mackenzie King’s government and its fleet were not ready for a shooting war.

Perhaps that is why the collapse of the navy’s major effort in the mid-Atlantic Ocean by the fall of 1942 remained such a highly guarded secret for 40 years.

By the summer of 1942, 35 per cent of merchant ship convoy escorts operating between Newfoundland and Great Britain were RCN. During the last six months of that year the full weight of German U-boat wolf-pack operations fell on them. In November and December alone 80 per cent of ships hit by torpedoes in transatlantic convoys were under Canadian escort. At the end of 1942 the British formally requested that Canadian escort groups with the Mid-Ocean Escort Force (MOEF) be withdrawn from the North Atlantic Run for re-equipping and retraining.

None of this was foretold when the Newfoundland Escort Force (NEF) was rolled into the MOEF in February 1942. In fact, Canadian Rear-Admiral Leonard Murray hoped to use his burgeoning surplus of escorts, and the easing of attacks in the mid-ocean, to address serious equipment and training shortfalls.

HMCS Restigouche, equipped with type 286 radar at the masthead and HF/DF antenna on the small mast at the stern. [PHOTO: DND/MARC MILNER]

HMCS Restigouche, equipped with type 286 radar at the masthead and HF/DF antenna on the small mast at the stern.
PHOTO: DND/MARC MILNER

It was also true that as American forces slipped away to warmer climes, a heavier burden fell on the RCN component of MOEF. However, the reduced force and its convoys now cleaved tightly to the Great Circle Route. They abandoned the barren Hvalfjördur anchorage in Iceland as their eastern terminus, and ended their eastward passage in the verdant landscape of Londonderry, Northern Ireland. With shorter passages and access to proper training facilities, improvements were inevitable.

It also helped that the Germans were busy elsewhere. In February 1942 the Germans introduced a new cipher for Atlantic U-boats, beginning a 10-month gap in the Allies’ ability to read their signal traffic. For the time being, that had little impact on MOEF because the U-boats were feasting along the American seaboard, and so there were a lot fewer wolf-pack operations against the main convoys in the first half of the year. Therefore, there was reason for hope in Murray’s command.

By early 1942 the St. John’s-based escorts were demonstrably better than they had been. Communications problems between ships, caused by a lack of training and equipment, were largely resolved. Signalmen improved, and proper visual and radio signalling equipment (especially radio-telephones) was eventually installed. Escort groups learned to operate together, and training facilities in Londonderry soon improved individual weapons and sensor effectiveness. The crews also became seasoned North Atlantic veterans. But many of the problems affecting efficiency were beyond Murray’s control, and beyond that of the RCN as well.

For example, Murray pressed for modernization of his corvettes to improve their habitability and sea-keeping, and to equip them for the kind of war they now fought. But as noted in an earlier story in this series, modernizing corvettes was not yet RCN policy, and so the short foc’sle versions—virtually all of the corvettes in Murray’s command—carried on, plowing their way from St. John’s to Londonderry and back. Ships designed for 30 to 40 men spent weeks at sea with nearly 90 on board, all sleeping in fetid and cramped messdecks. Refrigeration was inadequate for long voyages, so corvette sailors on the North Atlantic Run survived on Nelson’s fare of hardtack and pickled beef.

The most pressing equipment shortfall was the lack of modern radar to detect U-boats on the surface at night. In 1940 the RCN engaged the National Research Council to design and develop a Canadian version of the British set then being fitted to escorts, the type 286 set. This radar operated on a 1.5-metre wavelength which was good for locating big targets—like ships or Newfoundland—not low-lying U-boats. However, it was a start and it helped in navigation. The first trials were conducted on board His Majesty’s Canadian Ship Chambly in May 1941, and through the winter of 1941-42 this Surface Warning, 1st Canadian (SW1C) radar set was fitted in the fleet.

Lieutenant-Commander Desmond W. Piers on the Canadian destroyer Restigouche during an April 1944 convoy escort. [PHOTO: LIEUT. JOHN DANIEL MAHONEY, LIBRARY AND ARCHIVES CANADA—PA136286]

Lieutenant-Commander Desmond W. Piers on the Canadian destroyer Restigouche during an April 1944 convoy escort.
PHOTO: LIEUT. JOHN DANIEL MAHONEY, LIBRARY AND ARCHIVES CANADA—PA136286

This was an improvement over the British type 286. The latter was fixed to the masthead and did not move: it only searched straight ahead. To sweep with the type 286 it was necessary to swing the ship’s heading from side to side. The SW1C was also mounted at the masthead, but could be turned to sweep or search in a direction away from the ship’s heading. The early arrangement for “sweeping” was primitive: a hand crank attached to a set of bicycle sprockets and a bicycle chain that rotated a long pipe—carrying the radar cable—attached to the foremast on which the SW1C aerial sat. The latter looked like a postwar TV antenna. The operator could shift the direction of the set with the hand crank and read the angle of the set in relation to the ship. The radar echo came back onto a round cathode tube which had a range scale painted on it. The range to the target appeared as a spike along this scale, much like a modern heart monitor. The whole arrangement was better than the British type 286, but by early 1942 it was already obsolete.

By the time the RCN equipped its fleet with SW1C radar, the British were fitting an advanced 10-centimetre wavelength set, the type 271. This set could detect small targets, like U-boats, on the sea at considerable ranges. Moreover, the type 271 had an automated sweep, although the early sets could take as much as two minutes to complete 360 degrees. When this capability was connected to a Plan Position Indicator—a screen with the ship in the middle and the “sweep” going around it like the hand on a clock—modern radar was born. The great value of the type 271 radar, with its high definition and ability to sweep automatically, was to allow escorts to establish a tight radar barrier around their convoys.

The secret to the type 271 radar was a remarkable little device called a “cavity magnetron,” one of the most important technological developments of the war. Most scientists, including those in Germany, thought it was impossible to produce miniature radar waves. When the British brought the cavity magnetron to the United States in September 1940, the Americans were dumbfounded. The American writer James Baxter later called it “the most valuable cargo ever brought to our shores.” Canadian scientists were ‘in the know’ well before their American colleagues, but mass production of the cavity magnetron and the design, development and manufacture of the 10-cm radar set took time. And as with Canada’s larger industrial role, its radar scientists were soon part of an international Allied scheme, and not dedicated solely to the needs of the Canadian armed forces.

So the type 271 was developed in the United Kingdom and fitted to the Royal Navy first. Canada’s version of the 10-cm set for the RCN, known as the RXC, would not become available until 1943. It was a disappointment as a surface-warning set, but was retained as a highly effective aircraft warning radar. It was also a “plumber’s nightmare” for maintainers: the set was developed in the lab and then not redesigned for operational conditions. Virtually any fault required a complete stripping down of the set. The relative merits of the RXC will be explored later. What is important is that the RCN was still debating the merits of 1.5-metre and 10-cm sets in the summer of 1942 when the wolf packs returned to the mid-Atlantic. Reliance on a 1.5-metre set proved to be a source of critical weakness in Canadian MOEF operations in 1942—just as they had been in the St. Lawrence.

Apart from poor radar equipment, two other shortfalls seriously affected Canadian mid-ocean operations in 1942. The most significant was the shortage of destroyers. The RCN had just enough available for the NEF because the route to Iceland was comparatively short and the old ex-American four-stackers (destroyers) could make it. When the eastern terminus switched to Ireland in February 1942, only the six surviving River-class ships and the four-stackers St. Francis and St. Croix had the range. In theory, that left the RCN with two destroyers available for each of its four C groups (escort groups) in the mid-ocean. Compounding the problem was the fact there were no spares to allow for refits, training or damages. In the event, St. Francis was never reliable. The British filled the gaps in the C groups with their own long-ranged Town-class destroyers, although they, too, proved mechanically unreliable.

Destroyers were essential to mid-ocean operations because they provided the only effective strike force in the mid-ocean air gap, the area beyond the range of land-based aircraft where wolf packs operated on the surface with impunity. Quite apart from their size and powerful armament, only destroyers possessed the speed to sweep out, scare away shadowing U-boats and break up the wolf pack forming around a convoy.

It helped a great deal if these destroyer sweeps could be directed accurately, but to do that the escort needed another piece of new kit: ship-borne high-frequency direction finding (HF/DF) sets. This, too, was a marvel of miniaturization. All major combatants had land-based DF stations, but not everyone—and again not the Germans—thought it possible to make the sets small enough to send to sea. Once again the British did the impossible. With ship-borne HF/DF the escort could fix the transmission of each U-boat as it made contact, allowing destroyers to drive it off. In 1942 HF/DF sets were widely fitted to British destroyers, and they strove to ensure that each escort sailed with two so that fixes by triangulation could be made. Until December 1942 the only Canadian destroyer to carry HF/DF was Restigouche. Her captain, Commander Desmond Piers had ‘bought’ the set from the American naval base at Londonderry with a bottle of booze during a brief refit.

As events in the mid-ocean would soon reveal, the RCN should have been far more generous with its liquor.

Email the writer at: writer@legionmagazine.com

Email a letter to the editor at: letters@legionmagazine.com
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