Basically this is what I did for my Kaidai SS3 to make things easier for me in combat. Figured i'd share (:

Tools: • Timer
            • Piece of paper (Honestly, remember don't always look at the piece of paper.)
            • Pen
            • Grid spr file for Phase 3

Where: Friend/Fleet mate in a  private battle room.
 
Phase 1: Figuring out your o2 Time
                  Simple as it gets. I know you have that little dial that goes from green -> red and then the alarm goes off
and you get spammed by all those PHH everyone has. BUT. This is a more precise way of tracking it. The second
you press your dive button start your timer. When you the second you start to surface stop the timer. Write the time
down, or remember it for the other steps.

Phase 2: Torpedo Distance/Slow/Fast
                 Okay when you look at your torpedo in-dock what do you see? 4000m or something on distance?
Real helpful on the battlefield right? Not really. So! For this step simply fire your torpedo at nothing. and here is
where those dots on your line of fire come in handy. When the torpedo explodes look at which dots it explodes
near. Count back the dots. From now on when you get ready to fire not only think about hitting direct on, you can
also now precisely get proxmity damage. Do this for both Fast and Slow. Remember Fast = Close/ Slow = Far.
To make the dot thing easy. If your SS has a deck gun your using. fire the round to either your far or close distance.
(Preferably the far one) and use the tracer left behind from the shell as a quick refrence to where your torpedo will
explode.

Phase 3: Figuring out your distance submerged (ONLY IF YOU HAVE THE GRID SPR FOR YOUR MAP)
              Remember your submerged time? This is where the beauty of the grid and knowing your oxygen count
come into play. Simple go to a line like A/B 1/2. Dive,then start your timer. Go at your normal speed. Not OH. Figure
out how long it took you to cover 1 block. Subtract the time you got from your overall Oxygen time. This will give you
a rough estimate how long it would take to cover 1 block. The reason you dont do this is OH is because this way
you have some room to extend your distance. Better be safe than sorry. Using the number you got from figuring
out 1 block you can now add up what you need to see how much air it would take for 2,3,4 blocks etc.

Phase 4: Put the submerged distance to use.
             On your grid you should have A,B,C..etc and 1,2,3...etc. Find an average spot where you usually
would start in GB (Alpha or Bravo). When the match starts find out where you are EXACTLY on the grid. Not
"Eh.... im around Aish..1..". Lets say you start on line B/C number 2/3. If this is where  you start. Assume that the
enemy teams battle line is around 6/7 Line. Find out how far you have to travel on the grid before you MUST dive.
The second you dive check where you are on the map. Using the distance you learned in Phase 3 you can now
figure out how far your SS will go before you must surface. (Being that you dom't have to critical dive/ engage a
target.) From here you can now design your own battle technique. For example: I know i have to dive around C/D
3/4 if I want to get to the enemy carriers. If i dive early, i'll have to engage the front line BB's" etc. Do what suits you
best.

On a side not. Change it up! Don't use the same tactics over and over. Players will catch on to your routine which
is not good. (:

Hope this little guide/thing helps a bit with your SS's Goodluck!