So when you rank up you get more boff power slots to use.
Barring special purchases ($$$ ships) the 5 Tiers (En+Lt/LtC/Cmdr/Capt/RA/VA) give you:
3, 5, 8, 10,12,12 boff station powers.
Special purchases ($$$$ ships) give you:
3/4, 6, 9, 11, 12, 12 boff station powers.
Currently we end on 12 either way.
Once you're out of En+Lt tier ships these powers are broken into "Primary" and either "secondary/tertiary" or "secondary-secondary" with "primary" having more powers than the rest.
On basic ships this setup is 7/3/2, and barring specific cases (full-carriers) there's always an ensign station rolling about.
At RA/VA let us vote YAY for +3 boff station powers.
At RA/Va let us vote YAY for the VA/RA ensigns to become LT, and the last two powers to upgrade stations or simply add a 6th one (at LT).
At RA/VA let us vote YAY for MOAR POWARZ!