Depending on the type of sailing you do, probably can get away with using the RV service. If you're sailing within their current maritime coverage map https://api.starlink.com/public-files/maritime-coverage-map.... you're just using the direct CPE-Starlink-Uplink Station connection. Provided you're still in that coverage cell, there is really no difference to the entire system if you're 10 miles from shore inland or at sea.