this is what wiki says about type XXI:
Code:
Surfaced:
15.6 kn (28.9 km/h) (diesel)
17.9 kn (33.2 km/h) (electric)
Submerged:
17.2 kn (31.9 km/h) (electric)
6.1 kn (11.3 km/h) (silent running motors)
and this about VIIC which is one step backwards in HoI2 game:
Code:
Surfaced: 17.7 knots (20.4 mph; 32.8 km/h)
Submerged: 7.6 knots (8.7 mph; 14.1 km/h)
There is a huge difference in speed, you were right.
Forgive me on my mistake but its all paradox fault, they didn't improve the speed in their game
not only reduced visibility, but above all reduced visibility ??
Nope. Greatly reduced visibility and greatly increased the offensive capabilities.
Imagine a well protected covoy being attacked by a handful of VIIs:
the convoy is running at maybe 12 knots, too fast for the submergibles to attack the convoy submerged. So they must close in to the surface, use their snorkel and run with their diesel egines to even be able to catch up with the convoy.
The warships protecting the convoy have the ability to spot the submergibles way before they even come close to the convoy by using radar to spot the snorkel, they can send out aircraft to kill them off before ever reaching the convoy, and even if the submergible manages to dive it is neither silent enough nor fast enough to escape the depth charges from the destroyers.
That is why the Germans lost the battle in the Atlantic, the technology simply was outdated with the invention of aircraft based radar.
Now you have the XXI:
It can make a fully submerged attack run at the convoy, get a torpedo lock on a ship before the escorts even notice what is there, and then easily escape with their silent mode, fully submerged the whole time, nothing for a radar to get a lock on, and by the accounts of the US Navy which tested a couple XXIs in 1946, pretty much undetectable even if they parked their best ASW destroyers directly on top of a ship (they got the position radioed from the sub, but no technology available could detect anything meaningful).
One of the very few accounts of a XXI that saw service notes an attack run (without ever firing though) on a british warship. When the ship logs were examined by the Royal Navy later on, the British captain didn't even know the sub had the torpedos locked on them until he read the logs himself.
That is an incredible increase in offensive capabilites, that nowhere near found its result in the stats of HoI: a pitiful increase in stats, creatly increased costs made XXIs even less attractive in the game.
In reality, they ushered in a new era of the submarines (which ultimately led to the development of anti-submarine submarines, the only effective weapon against a modern submarine), so greatly could have changed naval combat if used in proper numbers (and with enough time to participate in combat).
So lower visibility is one small aspect that changed with the introduction of the first real submarine. Much, much higher offensive capabilities is another side of the XXI.
To compare the differences, it's best to examine a WW1 tank with a Panther, just that this jump in technology occured within a decade.
