To the OP, I may be able to offer some recent perspective. My son (Class of 2017 appointee) was recruited for crew by Navy as well as several other schools. I tried to stay out of his whole recruiting process, but during his visit to Navy, my son called me from the coach's office and said the coach wanted me to participate in their meeting as well.
What the coach said was instructive, and I think very relevant to your question. I'm summarizing, but he said that he looks for the following in a recruit:
- A "crew head". He wants someone who lives and breathes the sport, who commits fully to training and will commit fully to four years of rowing at Navy. What the athlete knows about the sport and what his HS coach says about him will be the most telling indicators of a crew head. An example -- the coach had a picture of a collegiate eight on his wall, and referred to it at one point, saying "you see that guy in the picture?" My son said, "Yes, that is Gern Blanston (or someone). He was in the Navy lightweight 8 at Eastern Sprints in 2006 when they finished first, gaining three seats on Princeton in the last 500 meters". I'm making those details up, but seriously, that is what happened and in that level of detail. I was kind of flabbergasted that my son knew all of that, and I think that the coach was too. He wants to see someone so into crew that he knows those details.
- A boat mover. He wants someone who can pull a good erg, obviously.
- A winner. Ergs don't float. You could be a beast on the erg, pull a really low number, but have terrible form on the water and no dynamics with your boatmates. Coach said that he wants to see someone who comes from a program with a legacy of success, who is used to winning through individual and team effort.
My honest opinion is that if you are already well into your high school career, and you are not already established as a rower, you will not be recruited by Navy. Keep in mind that they establish their recruiting class somewhere in the August - December time frame of each class's senior year. To do that, the coach has to know about you and about your record of athletic achievement in the months leading up to that, so for example in the June - July time frame between your junior and senior year. That naturally limits the amount of time you have to establish yourself in the sport, if you are not (and you indicated that you are not) already there.
By no means would I discourage you from jumping into crew and applying yourself. My perception is that if you arrive at plebe summer in great shape and with a couple of years of rowing experience, you would be an excellent walk-on prospect. I just would not expect the coach to recruit you.
Good luck to you in your pursuit.