Our son rowed all four years in high school and at USMA. The difference is that those at the college level who have never rowed before will have a bit of catch-up to do to make it into those upper boats if that’s a goal.
Know that you will spend hours on the ergs pulling until your lungs burn and you think you're going to pass out, and you might. You will also note that most erg rooms have small trash cans or buckets lying around to capture the contents of stomachs which every rower loses on occasion. And you will need to be prepared for twice-a-day practices and the three to fours hours or more out of every day that cannot be applied to academics. Rowing is not sustainable for the academically weak. You will also end up with two very wrecked hands in the process of developing the permanent callouses required for handling the oars proficiently. And sleep, never a mainstay of any cadet's/mid’s life, will become your most valued treasure; you will never get enough of it. Exhausted will become your new normal.
On the bright side, you may never find a higher level of comraderie than the binding of a crew or the intense exhilaration of rowing first through a finish line with spent mates who have given every breath and every ounce of their beings to finish well what is primarily a mental battle. Crew is more calling than sport.
I have posted this before, but here is a video that gives a good glimpse into a rower's world:
Crew is the definition of teamwork. A boat will not move unless ever rower is in sync for the entire distance. Each position in a boat serves a unique function, but those functions must be executed with a precision not found in other sports. The rowers become the boat. It is the boat that wins or loses, not the individuals who make it move. You will know very quickly if you love or hate crew. There is no in-between.
USNA’s rowing program is D1 whereas rowing is a club sport at USMA, so I’m sure the privileges extended to rowers at USMA (private facilities/boathouse, released from some routine duties, etc.) are matched or exceeded at Navy.
Good luck!