A reminder. I am taking from a mid 1970s edition of EB and a number of 1970s and 80s reference works. Some of this info, especially coming up to the
70s and 80s when data on the then newer ships was still relatively difficult to come by, becomes subject to interpretation, opinion and necessary
Thats okay. I welcome it.
WW2 (Sept 1 1939 to Sept 2 1945) saw extensive submarine campaigns on all the worlds oceans (and most of it's seas). The the Atlantic the principal
German U-Boat was the VII (Seven) type, a small but relatively effective craft when properly employed. The Type VIIC (Seven-C) variant was 220 1/4
feet (67m) long, displaced 769 tons on the surface, and was powered by diesel electrics at a speed of 17 knots surfaced and 7 1/2 knots submerged.
Armament consisted of one 3.5 inch deck gun, various AA guns and five torpedo tubes, four forward one aft. Either 14 torpedos or 14 tube launched
mines could be carried. Manned by a crew of 44, these subs had a surface endurance of 6,500 miles at 12 knots but, when submerged thier batteries
would remain active a little less than a day at four knots.
Three German designs warrant special attention ( according to EB): The VIIF (Seven-F) design was an elongated boat 254 3/4 feet (78m) long intended to
replensih other U-Boats at sea with torpedoes (25 spares were carried over its normal complement of 14 rounds) and fuel oil (199 tons carried,
compared with 114 tons in the standard Type VII sub. The ultimate diesel electric sibmarine evolved in the war was the German Type XXI (21), a 250
foot (75m) 1600 ton craft that could attain 17 1/2 knots submerged for more than one hour, six knots submerged for two days, or could "creep" at
lower speeds submerged for four days. These submarines were fitted with a device known as a schnorchel
that made it unnecessary for them to
break the surface to recharge thier batteries after operating submerged. The Type XXI had an operating depth of 850 feet (260m), more than twice that
of other submarines of the day, and was armed with four 33mm cannon ( twin mounts fore and aft mounted in streamlined barbette housings on the lip of
the conning tower) and six forward torpedo tubes with 23 rounds). Existing ASW forces would have had trouble coping with these craft if they had been
developed earlier of if the war had continued for at least another year.
A final German design of interest was the Walther turbine propulsion plant. The need for oxygen for combustion had previously prevented the use of
steam turbines or diesels while a submarine was submerged, and air was at a premium. Hellmuth Walter, a German scientist, developed a turbine
propulsion system using oxygen generated by hydrogen peroxide to operate the turbine while submerged. A simplified submarine, the "V-80" was built
in 1940 and powered by a Walther system, attained speeds of more than 26 knots submerged for short spans of time. After many delays the first Walther
propelled Type XVII (17) combat submarines were completed, which could achieve 25 knots underwater for brief periods, and a submerged run at 20 knots
for five and a half hours was achieved on trials. But these, like the Type XXIs were not ready in numbers for operations before the end of the war in
A notable German submarine development was the schnorchel
device (nowdays known by its USN anglicised name as the "snorkel"
invention is creditted to a dutch officer, Lt. Jan J.Wichers, who in 1933 advanced the idea of a breathing tube to supply fresh air to a submerged
submarine (Robert Fulton had a similar device fitted to his 1801 "Nautilus"
. The Netherlands Navy began using the snorkels in 1936, and some
fell into German hands after the capitulation of 1940. With the advent of radar to detect surfaced U-Boats, the germans fitted hundreds of thier craft
with this device to permit the operations of boats at periscope depth to recharge the batteries for underwater propulsion, with a lessened risk of
detection by radar equiped allied ships and aircraft.
Next: before we go on with Submarines in the Pacific, a history of Asdic and Sonar in the "Stone Age" ie. Until the late 1970s.....