German submarines/ Diveboats/ U-boats

[Isoruku_Yamamoto]

So i was having a discussion on submarine implementation and i was thinking to myself hey, the german U-boat development would offer some great options on this. 

So i made a raw draft of how you could fill a tech tree with german Subs- although i could probably also come up with US, Dutch and Japanese subs- if not more classes. I took the german ones first as i consider them to have a really neat historical development which you could put into the game nearly 1 on 1. 

Suppose you'd want a tech tree to start around tier 3- from the DD line i guess. You could even say that you'd only start at tier 5, but the typically slow gameplay of submarines would also quite fit the lower tiers i suppose. 

Even within the VII series, you could take the VIIA, VIIB and VIIC/41 as three follow-up ships due to improving characteristics between them. 
Then you could follow up with varieties on the IX boats as high-tiers (tier 8-9 or 8-10) and have the XXI sit as the tier 10, which is a ship that can really stay underwater for long times. 
while the lowest tiers can be filled by the Type I, II and V
Now i mentioned 8 varieties so far, so if you'd start at tier 3 it can simply be this

3: Type I
4: Type II
5: Type V
6: Type VIIA
7: Type VIIB
8: Type VIIC/41
9: Type IX
10: Type XXI

Premium Tier 8: VIIC/ 42 (increased diving depth, submerged & surface speed, slightly increased torpedo reload speed, at the cost of manoeuvrability)

Main characteristic of the german tree: good surface speed, 4 forward tubes and 1 aft tube, long ships which are reasonably manoeuvrable but cant go through tiny corners, good depth performance, weak AA, good diving performance but poor oxygen supply & poor resurfacing. Only Type XXI has good oxygen reserves. 

Torpedo ranges 8-12km, damage 12-23k, speeds 50-80knts, depending on tiers. Reload times should be long, around the 1 minute mark i think

Grtz Isoruku_Yamamoto

P.S. Topic is work in progress