My son is NROTC - the first summer cruise, after freshman year, was 30 days - evenly split - about 1 week in each specialties - SUBS, SURFACE, AIR and Marine. Last summer even the Marine option scholarships did same thing.
After that summer Marines do something different - Navy is supposed to have 2nd class cruise (after sophmore year) this year it was a 2 weeks enlisted cruise - is waivable for academics, the final summer - after your junior year - called 1st class cruise is MANDATORY - since we haven't done it yet cant say for sure the exact length - but it is supposed to be officer training cruise and should be 30 days or so - we will experience that next summer.
As others will say, budgets, etc could change things - just wanted to give you what I know - don't think it matters, but son is NROTC at VMI. larrys mom