Are those frigates you sailed on, ID?
I present the XXI Type U-boat, the final U-boat to go into production, and the prototype for every post war submarine.
Having been designed and commisioned in 1945, successes were few (maybe even nil). After capturing a number of them the US navy copied pretty much every aspect, as it was far advanced from anything the Allied had.
The bridge and anti aircraft emplacements of the type XXI.
Just visible is the Schnorkel.
The submarine was faster underwater than surfaced.
Surfaced it could reach up to 15 knots under the power of its 2 diesel engines. Underwater, it could reach a revolutionary 17 knots under the power of its 2 electric engines.
The type XXI was equipped with a Schnorkel, which was effetively a snorkel used while submerged, so that the diesels could be used.
While submerged, a submarine could not use its diesels, because ther was no air-flow; the diesel would suffocate the crew with fumes, while asphyxiating them. This allowed only the electrics to be used underwater, with a limited battery time.
As the Allies had full air superiority, this meant that the subs had to remain submerged all day. Obviously a sub could not propel itself alday on the electrics.
The Schnorkel allowed it to propel itself with its disels.
The Mark XXI was aso equipped with RADAR (which was often left off; as it was primitive, compared to that of the allies, and it gave away the position of the submarine, ruining any surprise; and without surprise, a sub is useless. Even small arms fire can be deadly to it).
The sub was armed with six torpedo tubes, all located in the fore. Oddly, this was a step backwards (almost) for the Germans, as it was the first sub for a while to not have a stern tube, firing just below the props.
The XXI also encompassed a revolutionary new loading system which allowed extraordinary diligence in firing.
Had it come into production sooner, it could have made the war very, very painful for the allies.
The XXI was the first of a new breed of vessels.
Unlike the previous U-boats, or anything any country had produced, the XXI was a true
Submarine, capable of sustaining itself underwater for long periods of time.
All the other U-boats were merely extremely weak surface craft with the option of submerging. In fact, quite unlike Hollywood would have you think, the majority of U-boat attacks were conducted not submerged using the periscope, but surfaced, at night, with the Kaleun, First Officer, armaments officer, and the Watch officer, using a binocular like device called the UZO (Unterboot ZieleOptik).
Phew, my fingers and brain hurt after that
Bonus shots of U-boat Kaleuns:
Gunther Prien was the archetypal U-boat hero.
Gunter Prien hd managed to sail his U-boat right into Scapa Flow, the British naval headquarters, and sank the Royal Oak.
While sympathetic to the Nazis, even Churchill had commended him: "a remarkable exploit of professional skill and daring".
Prien's boat was lost in 1941 with all hand aboard.
Otto Kretschmer was the highest scoring ace of WWII, with 46 boats sunk, for a total of 273 000 tons.
Kretschmer's boat was sunk, but he along with the majority of the crew escaped, and he was captured.
Werner Hartenstein, after sinking a ship was horrified to see it had contained hundred s of women and children. He surfaced, and packed the inside and deck of his submarine with survivors, as well as tying lifeboats to the sub, and sailed tghem to allied captivity, where his boat was attacked, and they were forced to submerge and escape.
His boat was sunk with all hands in 1943.
Fritz-Julius Lemp got the first U-boat kill in WWII, sinking the unarmed liner Athena the day Britain declared war on Germany,
He later commanded the U-110,famous for being under his command when it was captured afloat by the HMS Bulldog, allowing the British to gain access to the Engima codes.
While the British were boarding the abandoned U-boat (which its crew had abandoned, thinkijng it was singing), Lemp disappeared, allegedly having realised the British were boarding, jumping overboard, swimming back towards the sub before being shot by a British soldier.