Repair, restore and Potential stats are pretty much useless for a sub BO.
All present subs have so low useable displacement you'd be a fool not to
skeletonize the BO down to 1 or even 0 sailors, which reduces his true ability to
about 0.
As potential on a BO only gives you longer guidelines and allows you to spot the
shell splashes at further ranges, it's especially useless to a sub BO.
Unless future subs get enough useable displacement after the fat
engineers/repairers/planesman/sonar are on the sub, I wouldn't hold out for super
stats on a sub BO. A good repair stat is all you might want in case this miracle does
ever happen.

Rep/Restore on a Planesman is really not that beneficial. By the time you class to Chf.
Planesman (78) your growth is in the negative. After you class the sailor to 2nd
planesman your growth is equal to the original base of the sailor. Growth is reduced by 7
at 1st planesman and another 6 at Chf. planesman.

This however is an effective strategy for BO and Sonar (if you choose to class to 2nd
sonar and leave it), but bear in mind the growth will be relatively low compared to a
normal Rep.

I would agree that the Restore and Repair ability rates would be your 2nd priority in
selecting a 14+ Potential for your sonarman, planesman or Bridge Operator positions.
You only have room for the engineer position through SS4 and no room for repair or
restore, so look for strong 11/10s in those two categories.

I would venture that a good 14 potential with 11 repair/10 restore is as good as an
Elite with 16 potential and 9 repair/9 restore.

Bridge operator, Sonar, and Planesman would benefit from higher Repair and
Restore stats but not engine. For any sailor, a repair/restore of 10+ is a nice
bonus but don't worry about the engineer stat as it ONLY applies to an engineer
sailor.

Your long range goal needs to ensure you are not missing key sailors in your later
ship stages.

You will need 4 armament sailors. Two will go down the heavy torpedo route and
two down the heavy gunner route. Use your two with the best torpedo rating for
torpedo and the two with ACC or RLD for your gunners.

Your Bridge Operator, Sonarman and Planesman are Potential and try for 14+, with
an 11/10 in egr/rpr/rstr if possible.

Once you get to the U-Flak (BO L74), you will need Two Heavy Torpedomen (L59
Front and Rear) and Two Huge Gunners (L74), and Sonarman, Planesman, and
Engineer. in your support slots.

During the SS1-SS3 period, only 1 gunner slot exists. Cycle the two gunners in your
main gun slot during the progression and keep them light. You will want to use your
U-Flak guns. They are the best Machine gun type AA and they sink ships too. Upgrade everyone, vets and experts. Upgrades to your BO will affect your crash dive
and recovery speed, so good potential makes a difference.

I was looking to do the same thanks

Go to gunner at 21 and then torper at 44. WHATEVER YOU DO, don't make him a HUGE
gunner when it's available.