SeaDog spins some truth, some fiction in his post cats. One thing you youngsters need to reel in nice and early is that there is no common sense in the MARS profession. No, they will not look at how much they have dumped into you for trg and say "hey, we should keep this cat around, he cost us tons!". One of my buds out here just pulled himself off of the ORO Course, so ostensibly the Navy has dumped just over 1.5 million to get him there, then another 1.2 million for the ORO Course. Guess what? They almost punted him, but he barterred for a recruiting job inland. *If nothing else, this job is never a sure bet, even after you are post d-level. However, as we are currently over 175 MARS Officers (post d-level) short in the fleet today, chances are they will keep you around. However, at the NOPQ stage, and up until you pass your d-level, you are expendable. Remember, you are not useable to the career mangler in Ottawa until you are done your d-level tour, then you are eligible for purple jobs (recruiting, basic trg, JHQ etc).
So Fred, don't buy a house until you are done your d-level course. Until then you are the peanut shells beneath the boots of Ottawa.
SeaDog, yes, most cats get several cracks at their NOPQ (C of C II for us oldies) board. However, if you can't pass that board after 2 or three cracks, they need to seriously consider another career path, I just sat a TRB for an unsuccessful NOPQ candidate and we booted him into TDO. We usually send the dead weight to either Int or TDO, somewhere far from the coast, Ships, and the ability to put people in body bags.