I've figured that it took about 3 years active duty to go to 03 (Lt) from 01 (JG). (To CPT from 2LT in army terms)
Does anyone know Kerry's various rank at any given year of his military service?
You're close but you missed one rank. An Ensign is O1.
A Swift boat OIC was either a Lt. j.g (O2) or Lt. (O3). Kerry would have made O2 sometime before he arrived there for his Swift boat duty.
Sorry. It's the Army in me.
I always louse up the Navy ranks. And don't even go to the enlisted. They've got more letters and numbers than a code sheet.
:>)