For the bad reviews out there. 1 - RTFM (google it) 2 - Dont be a moron I live in a area where the intercostal waterway meets the Atlantic and knowing the tides makes the difference between fishing in your boat or taking your boat for a mud walk. Setting the clock per instructions provided accurate information (see RTFM) The clock face provides quick and easy to understand data on all the information a boater would need to know (see dont be a moron) Its a great App at a great price.