WELCOME ABOARD!
I like what you're suggesting, but as a former American sailor it looks odd to me. In the US Navy officers have to do at least some studying before they are assigned to head a division, and here there is no such thing as an unqualified petty officer. Earning the qualification is what gets them that promotion. I wasn't even a PO, just a lowly seaman, but the radio section was my permanent position and if I had stayed in I would have become a radioman, which is a petty officer position.
Are you using SH3 Commander? It helps you control your career, including the option for a Realistic Career Length, which retires you after a certain combination of time and patrols. It does a lot of other things as well, but none of them are related to what you addressed here.