Just keep working the process - you just don't know what will be considered waiverable.
We had a USNA sponsor daughter who went Surface Warfare (SWO), got very seasick on cruise/underway periods. She had to come off sea duty and go through a med board, which found her undeployable, and essentially stalled her SWO career. During the uncertainty period, she took an MCAT cram course, did well on the MCAT and successfully applied to USUHS and was able to switch careers and go Med Corps. Funnily enough, it wasn't always the heavy pitching and rolling storm seas that greened her up, but slow oily cross-wave seas that pitch, roll and yaw a ship simultaneously. Three-dimensional challenges to the stomach and inner ear workings! I don't recall if she needed a waiver to get into USNA, sorry, or if she had a history of motion sickness.
Airplanes, subs, ships, small boats, YP boats at USNA - lots of opportunity for motion sickness if someone has a tendency toward it. Standards for accession are always tougher, and motion sickness could be a biggie.
Harbor cruise, ferry boats and cruise ships typically have stabilizers which flatten the ride for the comfort of seasick-prone passengers. Very different than riding in a ship's small boat from the anchorage to the pier, bouncing through the waves, or waiting on a choppy sea on a hot day smelling engine exhaust while waiting to get up to the ship's landing platform.
