You must have been gone a long while.
Yes hh are a pain for any ss but you can adapt. It is still easy to get 100k+ in any given battle if played right. Obviously the first thing is to avoid sonar. Without a sonar ship bb's cannot see you. My personal tactic is to engage other ss on my teams side of the map before venturing into enemy territory. Rushing across and attempting to attack enemy bbs is not a recommended strategy.
Stick with it. Pre determine where sonar ships and ss are before battle begins and during the course of the battle.
Good luck!
Cheers,
Austin 

Submarine gameplay changes  2014/2016.

- When submerged repair rate is 70% lower then the true abilty.

- All submarines regardless tier and crew can CD the same amount of time. ( a ss1 with no crew can be in critfdive the same amount of time as a SS5.5 with 120 overvetted crew)

- HH explde faster or CD became slower as it is NOT possible anymore to CD on time when HH are shot from close range. ( I dont have my video edit program anymore so I cant tell for sure if its 1 or the other) https://www.youtube.com/watch?v=IwMPrZGVgWU is now not possible anymore.

- When you CD you have to do a complete stop to change back to submerged.

- Submarine Torpedos move slower.

- Sonar for surface ships got a huge buff.

I just played a few games since they unbanned the account I play on so there are possible some things I missed.

Thanks for the response and the updates, seems I missed alot! It was almost 5 years away!

I have tried many strategies to "adapt" however I still think the rules of combat for SS are unfair. There is a large number of ships mounting HH and usually more than one ship fire at you making it impossible to escape. if in the middle of the battle it is hard to even get to the "i" to CD before the HH explode not to mention the time needed to CD. One ship can hit you with a large number of HH at one time enough to destroy you X 10 while you need at least 15 torps to "actually hit" a large BB in order to see a visible damage. 

In conclusion, the instant explosion of HH, wide range, level of destruction and the fact that  any ship can mount HH is clearly unfair for SS and should be adressed by NF.

Maybe this helps.

1.Change your key bindings!

A - speed down

D- Speed up

S- Dive

W- critdive

2.Dont fight subs in enemy HH controll areas.This isnt always a option as plenty sub players just stay at the BB line.

3. when you shoot at BB shoot all torps at once and CD right after you fired to avoid being killed/cripled by undodgeble HH. This will give the BB the time to run so get as close as possible when you fire your first volley.

4. Set sound to extended (not sure about the name) in the options. Now sometimes you can hear enemy/ friendly sonar by a ping sound. This isnt reliable.

5. When Sonar+HH find you youre dead, accept it.

Thanks for all the tips.