OTPs grant you your commission, or in the case of merchants, your Able Ticket.
Damn... we missed that...
IN Other editions, Merchants have a commission roll (4+ on 2d6), and the following ranks.
O1 4th Officer
O2 3rd Officer
O3 2nd Officer
O4 1st Officer
O5 Captain
O6 Line Captain/Commodore/Senior Captain
I'd say no, tho, to JO, and simply grant T20 O3 Petty Officer, due to retirement benefits issues...