Unless you are near a port dont bother.
Working a high vantage point along the Atlantic coast, I sometimes see large cargo ships along the distant horizon. I downloaded this app thinking it would help me identify the ships. It doesnt.
Unless you use this app near a major port its kind of useless. Definitely not worth $4. It only tracks vessels within a few miles of major ports.
citizen jay about
Ship Finder, v9.0.0