Here is the full list of all 17 NAVYFIELD achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Play NavyField for 200 hours to be Admiral
Play NavyField for 150 hours to be Vice Admiral
Play NavyField for 100 hours to be Rear Admiral
Play NavyField for 80 hours to be Rear Admiral Lower Half
Play NavyField for 70 hours to be Captain
Play NavyField for 60 hours to be Commander
Play NavyField for 50 hours to be Lieutenant
Play NavyField for 40 hours to be Ensign
Play NavyField for 30 hours to be Chief Warrant Officer
Play NavyField for 20 hours to be Master Chief Petty Officer
Play NavyField for 9 hours to be Petty Officer First Class
Play NavyField for 7 hours to be Petty Officer Second Class
Play NavyField for 5 hours to be Petty Officer Third Class
Play NavyField for 3 hours to be Seaman
Play NavyField for 1 hour to be Apprentice
Join NavyField game to be a Recruit
Play NavyField for 500 hours to be Fleet Admiral