Here are the MARAD listed Maritime Academies in the US.
They are:
US Merchant Marine Academy
California Maritime Academy
Great Lakes Maritime Academy
Maine Maritime Academy
Massachusetts Maritime Academy
SUNY Maritime Academy
Texas A&M Maritime Academy
Here's my knowledge of them.
US Merchant Marine-long considered excellent
California Maritime Academy. I employee a young engineer who went there. Very impressed and she loved the school.
Great Lakes-No knowledge
Maine-Know a few who went there. Consider it very good.
Massachusetts Maritime Academy-I employee an engineer who went there and will argue with anyone it's the best.
SUNY-I've talked to captains who went there and were happy with it.
Texas A&M-I asked the above mentioned engineers and they both hold it in high regards. It also has direct commissioning programs for the Coast Guard.
Note that all of these schools have close relationships with the military but none require it. They also run much like military schools to build the skills and discipline.
I don't think you can go wrong with any of them. The Cal Maritime Grad I mentioned above went to the University of New Orleans School of Naval Architecture and Marine Engineering for graduate school. However, she noted that while it was great that their undergraduate program was less intensive, less hands on and more theoretical. Also because it's not MARAD you don't get an immediate license upon graduation. (3rd Assistant Engineer).
The MARAD schools typically have their own training boats plus require you to train on commercial or military vessels.
Your son should also look at the specific programs and degrees to see which ones fit his interests best. There are programs designed for facility rather than boat preparation, those emphasizing naval architecture over mechanical and electrical skills,
Best of luck to him.
There are those who will attempt to dissuade him and say you learn by hands on, not schools, and he'd be as well off going to a maritime school, not college and working at a yard or something. I will agree some have, but argue strongly if one wants a strong career as a professional engineer, go to one of the Academies mentioned above. I've seen the difference.