Well, here is my take on the 3000 yards shots. They happened and with some success. Doctrine was 1500 yards are less to take the shot. I would venture to guess any error in calculation at 3000 yards will be much more pronounced then at 1500 yards. So yes, .5 of a knot at 3000 yards could be a football field miss. Also, doctrine called for 3 torps because there was other factors involved that spoil the skipper whole day. Water state, currents, etc. I find that the ingame speed is always a whole number actual and not a number and .5. Question is, if your calculations are always coming up .5, which way do you go? Round down or round up? I usually round down. I get to my 1500 yard or less (BTW, I use the O'Kane method all the time now) and send out my first torp just as the bow crosses the line on the scope then the others at the larger structures of the vessel. Very rarely do I miss forward or aft of the vessel. I do not use the lock anymore. Waste of time IMO. Get in there, be aggressive and fire when you can see the rivets on the ships
Get the speed right on the target and the rest falls into place.
Oh, some one mentioned changing the torpedo speed as you fire them. If I'm really unsure of the speed, I will dial in the first to what I believe the speed to be, the second one knot slower and the third one not faster. One of them, if not a dud, will find the mark.