- Author
- Downes, A.M., Captain
- Subjects
- Biographies and personal histories, WWII operations, History - WW2
- Tags
-
- RAN Ships
- None noted.
- Publication
- September 2010 edition of the Naval Historical Review (all rights reserved)
This article is an edited version of a talk given by Captain A.M. Downes to the Company of Master Mariners, Sydney Branch, on 24th November 1993.
Tonight I want to talk about the fiercest convoy-U-boat battle of the Second World War. It was, in fact, the turning point of the War. Up until then, the U-boats had almost succeeded in starving Britain into submission – with all that that implies. This was the scrap that finally turned the corner for us.
In 1939, Germany did not have very many U-boats but they soon proved to be a very effective weapon. As the war went on, Admiral Dönitz, who had been in charge of the U-boat arm, was made Operational Head of the German Navy in late 1942. The three big ships, Scharnhorst, Gneisenau and Prinz Eugen, had made their successful dash up the English Channel in early 1942 and were now bottled up in German ports. He paid them off so as to provide the men to man the seventeen U-boats that he was building every month. At the time of this battle, Germany had had some 400 U-boats in commission, building or working up.
17 new U-boats per month
These U-boats were fitted with torpedo tubes and a decent-sized gun for surface attack. To detect shipping they relied on visual lookouts and on good quality hydrophones. Their greatest asset was speed – whilst they could only do 2 knots, with bursts to 4 knots, under water, on the surface they could steam at between 14 and 16 knots. Once a convoy was detected, they would shadow it, reporting directly to Dönitz and to other submarines in the pack. They would then try to get ahead of the convoy where they would lie in wait. In daylight hours they would go deep and try and attack from inside the convoy itself, but their favourite tactic was to attack down wind and sea on the surface at night, submerging as soon as the torpedoes had been fired. They did not have radar but did have a radar detector which was geared to the 10 cm wavelength. Unfortunately for them, we were using a 3 cm wavelength which they could not detect. Their one weakness was that they had to report daily by radio to Dönitz who closely controlled them and those signals could be D/F’d from shore, and in some cases decoded and read by ‘Ultra’, the secret signal decoding section.
British Escorts
The British Escort Forces at this time comprised older destroyers, with one boiler removed and replaced by additional fuel tanks to give greater range, new frigates and corvettes. We all had good radar but this did not have the modern display, only a single small cathode ray tube which gave a distance, and a hand-trained aerial to give the bearing.
Asdic, the underwater detection system, was similarly hand-trained and effective in most conditions to about 1500 – 1800 yards only. However, because of water noise, it became pretty useless in really heavy weather and at any speed over 15 knots. The Asdic beam worked basically in and just below the horizontal plane with the result that a submarine echo could only be tracked down to some 100 – 150 yards in front of the ship, and it was then guesswork as to precisely what the submarine was going to do until we were in position to drop our depth charges from the stern. So the Admiralty started fitting some ships with Hedgehog. Now Hedgehog is an ahead throwing weapon firing off 24 bombs with contact fuses. These formed a circle of some 70 feet in diameter about 200 yards in front of the ship. A bomb that exploded against a submarine’s casing was powerful enough to blow a hole in the pressure hull.
Finally, one or two ships of every Escort Group were also being fitted with H/F D/F (High Frequency Direction Finder). This was a rather inaccurate instrument but could detect submarine radio transmissions and give an indication of which direction the attack was likely to come from and the very approximate range (either groundwave or distant) of the U-boat making the signal. Our own ship HMS Tay was the only ship so fitted in B7 Escort Group.