I used a site called WWW Tide and Current Predictor, to check tide information against the Perpetual Tide System in the latest version of Chart Navigator Pro. What I found was almost none of the information from these two sources matched. Obviously one source is right, but which one is it?
The WWW Tide and Current Predictor web site offers the following disclaimer:
"Do not use this program as a basis for any decisions that could result in harm to people, other organisms, or property. Check these predictions against officially sanctioned tables. Agencies like NOAA exist because there is a need for certifiably correct tide predictions. Do not rely on these predictions if you need guaranteed results. There is NO WAY we can get certified data on a zero budget. We rely on users like you to tell us when something is wrong. Please continue to do so."
The tides and current harmonics included in Maptech Chart Navigator Pro are from a database provided by NOAA. While we have found (and corrected) some errors in how we interpreted the data in years past, in every recent occurrence when a customer has located what it is believed to be an error, the predictions in Chart Navigator Pro have matched the official NOAA harmonic perfectly.
That having been said, if you provide some information on what tide stations you are seeing this discrepancy, we will compare them against our various sources (as well as the WWW Tide and Current Predictor web site) to ensure the accuracy of our product.