Same here just took it up the other day.
second missions come to an early end though, still have 10 fish but thanks to damage if i drop below 60 feet i fall apart

not a good idea to sneak into a convoy or harbour then.
trudging home slow as i can. cant surface for more than 2 seconds in daylight, god tells the IJA where i am if i do
anyways i somehow, more by luck than skill got a moving large passenger ship in the midst of a task force at about 1700. used all 6 fish. possibly the first sank her, but thats not important. 19K of ship is worth 6 fish.
i would say i average 4 tubes on a moving target now, unless conditions are perfect.
i certainly havent got any 100K patrols anymore.
im also less afraid of using my torps now, in the past i would ignore a 7K ship, and go for a task force or convoy instead.
now i will happily spend 3-5 fish on that one target, and be damn gratefull i had so much time to set up a nice attack
gauging speeds always going to be an issue. lets hope they sort that out.
seems im running into some other troubles now aswell. tried to head towards a convoys, that had me dodging depth charges for about 45 minutes.
tried to enter a harbour and was chased back out to sea
i think that they must be learning theyre trade.