The Battle of Britain Five Months That Changed History, May—October 1940 by James Holland (z-lib.org).epub

neither hit, although one did explode, alerting the destroyers, which then
peppered U-47 with depth charges. It was lucky to escape. On its return,
Günther told Dönitz the men could not be expected to fight with a ‘dummy
rifle’.
‘Prien’s opinions were shared by the other U-boats’ crews,’ noted
Dönitz. ‘Faith in the torpedo had been completely lost.’ Morale, which was
so important for crews who operated in such physically and mentally
stressful conditions, slumped. The problem was partly because the magnetic
detonation pistols were too sensitive but also because the British had
worked out a system of degaussing which reduced a ship’s magnetic field.
The other problem was that too many torpedoes were losing depth as they
travelled through the water. The first problem was resolved when a British
submarine was captured. Examining the detonation pistols on its torpedoes,
they found them to be far more effective and so copied them exactly. The
depth-keeping defect was also partly resolved. Thus having had six weeks
off duty in which U-47 had been repaired and refitted, and armed with
much improved torpedoes, Günther and his crew had once more set out for
what U-boats were best suited to – hunting and destroying merchant
shipping.
And they had had good hunting too. Since the sinking of
Balmoralwood, U-47’s luck had despatched a further six vessels, amounting
to nearly 40,000 tonnes of enemy shipping. Now, on this grey July morning,
a big 15,000-ton prize awaited it. All the crew were wondering whether the
torpedo would blow. On board, there was silence, except for the voice of
the Bootsmaat, the coxswain, counting the seconds as the torpedo sped
through the water. Thirty, thirty-one, thirty-two, thirty-three – then Günther
saw an eruption just below the forward funnel and a moment later heard the
sound of the explosion dully ripple through the submarine. ‘Bull’s eye!’ he
called out. The crew cheered. Keeping the boat at periscope depth he
watched carefully for the next quarter of an hour. The ship had stopped and
was beginning to list.
Satisfied that the ship was finished, he ordered them to dive out of
danger, resurfacing a little over half an hour later. ‘No sight of the enemy,’
he noted in the log. ‘I assume that the vessel has been sunk.’ His
assumption was correct. All that remained of the liner, Arandora Star, was
a wide patch of oil, bits of debris, and a few over-filled lifeboats and rafts.
Günther had been right to assume it was a British vessel and thus fair game,