Just an FYI...

There is a tendency to reduce the crew size on your sub's bridge operator.   I don't have a real problem with this tactic as the early BOs are pretty insignificant and whatever you can do to help with sonar, planesman and torpedo reload is more important on low level subs.

However, I now have a L120 bridge operator and a full complement of supports that provide maximum speed, OH duration, Sonar and air recharge capabilities.  My gunlines are useless in that the sub has no weapons that can shoot anywhere near the distance on my guidelines.  However, the guidlines assist me in knowing the estimated gun range of the BBs nearby.   I can ascertain the distance of BB1s and BB6s fairly accurately, allowing me to surface and recharge where safe.

But what is even more important is my range of vision.  When I am submerged, my periscope range is excellent and only about 10% less than when I surface.  This is because I run 140 vets and the rest experts. This is a lot of weight I could sacrifice for a little more armor, but what it brings to the game is that the BBs on my team behind me can see the enemy without the need for a scout.

When I add on the tune-up for added sight range, the difference is significant and it really helps our side during battle.  Aside from whatever vision it brings (not sonar based sight range); it also brings added repair and SD.  

Awhile back I burned thru several hundred experts on my BO (netted 10 vets). Afterwards my BO's vision was significantly reduced and it had a very negative effect on my tactics.

If you doubt what I am saying, the next time we are on the same team take a look at my range of vision from my perspective.   I can pick up enemy ships in the forward shadows a lot further out than what scouts usually see.