So I finished Naval Academy with excellents and started a career. I went on my first patrol and boy did I have a great time. I started in 1939 in a IIa class sub I believe it is. Wow, talk about a relic

. Holds all of 5 torpedoes, no aft tubes, no other weapons, no nothing. But, she's mine and I'm gonna make germany proud with her.
Anyway, I was ordered to patrol a sector, so I head there, manage to sink 4300 tons of merchant vessels and then head back. Saved and quit. Came back later, loaded the save and accidently deleted it. DOH!

Oh well, I had such a good time I don't mind doing it again. This time on my way to the sector I'm ordered to patrol I run across a British C2 Cargo ship. Though its still marked as neutral since I guess War hasn't been declared yet, I decide to sink her anyway. I'm getting better at lining up shots (though I still let the computer do the torpedo solutions) and figuring out how to intercept, so I figure out where the ship is going to be and lay in wait. It comes across perfectly and I release a torpedo. Direct hit just slightly infront of the middle. The boat slows down a bit...and then keeps going regaining its regular speed, only now starting evasive maneuvers. Ok...so I let another torpedo go. Another direct hit, pretty close to where the first one hit. Nothing. Slows down 1 knot for a bit and keeps going. Now I'm dumbfounded. What's going on here? Annoyed I stalk the ship and actually make a point of getting on the other side and getting ahead of it. Finally I line up for another shot, direct hit, middle of the hull and this one sinks it immediately. Three torpedoes it took. My question, is this normal? Later I came across another C2 Cargo ship, wasted my last 2 torpedoes on it and it just kept chugging along despite the gaping hole in its side. I guess 6200 tons isn't bad for my first patrol, but c'mon. What did I do wrong? I don't have any mods installed yet, just FYI. Also, I thought this weird because I managed to sink other merchant ships on the first patrol with one torpedoe normally. Those were only 2000 tons of course, so is that the reason?
One other question. On the way back from my patrol I obviously make liberal use of time compression. Well for some reason at some point it stops letting me go all the way up to 1024. I know in some views it limits you to 32 times, but now even on the navmap I was being limited to 8 times?! Any ideas why that's happening? Just a bug?
Regardless, I'm loving this game and after playing it for awhile look forward to addin the GWX mod.