I am a ship Master in command of Crude Oil Tanker(s). I quote this information so that you may be aware that I know something on the subject of tides.I just started using this application. The interface is stunning; there’s no doubt about that. I was interested primarily in the Apple Watch compilations for quick and easy view of tidal information for areas I am transiting. Primary source of data for planning, execution and monitoring is Admiralty Tide Tables (ATT).I have observed to my surprise (and at least a little shock) that the tidal predictions were off in predicted heights by around 20 centimeters while the times were off by a couple of hours from those calculated with the ATT. The location observed was ‘Bonny River Bar, Nigeria’. The other app that I have been using give me the same times and heights ad the ATT indicating that the information generated by this app may be erroneous. I took screenshots for my records.Inaccurate information for even one location makes the data from this application unreliable and untrustworthy to me as I can never know which other location may be off.I recommend that anybody using data from this app for anything that may impact life, environment or property should exercise caution.