NOTE about Type II: About sailors that you CAN use to work Torps tubes or MIne silo,
{KM Sailor} at 37+
{KM Support Sailor}at 37+
{KM Armament Sailor} at 37+
{KM Special Force} at 37+

I dont agreed about this comment: Type II is the best SS1!! loaded with mines you can do a lot of damage


(sorry my english)

Here in NFNA is possible.
But for speak more exactly
{Neutral Sailor} beyond level 25 CAN'T BE classed to {National Sailor} and HE EARN XP normally (at 140%) but never be class.
{National Sailor} CAN BE class to {BO} {Armament Sailor} {Support Sailor} or {Special Force} starting in level 12 or {2nd Seaman} starting 20.

Here the important thing is understand the difference between {Neutral Sailor} and {National Sailor}

I can say this because I'd try this method when I'd study the sailor system for use with Submarines like 2 years ago.
This is a very dangereous path to follow because any error when you class your sailor and the whole crew can be hurt. So put all your ATTENTION and be conscious of you want and how you can reach thats you want for your sub.

********** EXPERIMENTALS METHODS FROM HERE!!!! *************************
In my case I try first LINE with a IJN sub doing (keyword: TRP: Torpedoman PLN: Planesman SNR: Sonarman GNR Gunner)

1 BO Delayed as {IJN Sailor} untill 62 [13pot/22Rep+Res]
1 TRP delayed as {IJN Sailor} until mid level (I think it was until 62) [10trp/22Rep+Res]
1 SNR delayed as {IJN Support Sailor} until high level (I think it was until 78) [13pot/22Rep+Res]
1 PLN Normal Classed but [13pot/22Rep+Res]
3 ENG Normal Classed (elites and +12)
1 GNR delayed as {IJN Sailor} until high level (I think it was until 78) [11Acc/11Rld/22Rep+Res]

I´d need another BO, 2 Torp, SNR normal and 2 GNR normal for support while leveling the delay sailors.
Thats training was a LONG path and now I will not recomend to follow. I learn a lot about tactic as sub doing this path, because you have so little element to survive.
But the easy path is take a FIRST LINE AS BB, because you have much more xp much more sailors training at once and no xp nerfing for torp att and you can play BLITZCRIEG and more more more... Remember that its a BB oriented game!

Next experiment was a KM sub crew
This time I increment the delay in SNR and TRP till 90
Note that you REALLY need 2 GNR for U-Flak AT 74 LEVEL. So I delayed them untill 90 lvl as {KM Sailor} too so they can add repair to SS4.

This time was awesome. A KM SS4 (Uflak) with high Repair rates AND guns is so funny and from lvl 90+ is just adrenaline shots! If you can reach 40 knots and u can rep Crits damages fast you have extra handicap against others subs.
Note that in this 2 experiments I do not skelotonize any sailors (they have less TOTAL sailors as result from delay class method) include BO: these BO are "FAT" ones. They add some repair but a lot aof tons too.

(Each step was like one year play!!)

The 3rd experiment was leveling "One sailor" BOs as explain Invinciblor in this guide. I let TRP as normal this time because I prefer skelotonize them just to reach Torp cap (1kk for KM; u must multiply [Total sailor] x [Torp Displayed ab] x [perc]) and free sailor/weigh space for others ship's functions.

This free weigh for high level Engies so you can reach speed cap. Note that principal advantage of the method is You can buy in trade system the normal classed sailors (Engies and TRP and REPAIRS if you prefer those in R slot)
Of course I have a lot of mathematical stuff behind this and I can justify with formulas each step.


NOTE THAT ALL ABOVE ARE EXPERIMENTAL METHODS AND YOU CAN USE IT TO YOUR OWN RISK!!!

Critical dive rate is not effected sailors, its is a set value for each SS. KM SS4 has a quicker dive time than other SS's.