Or maybe not. Before our recent June charter, I purchased and installed the Navionics app on my iPad, and checked its accuracy using a Dual Electronics XGPS150A receiver. It was right on in comparison to other devices. Using the BVIPirate's set of 8 waypoints, I then created and saved a route into Savannah Bay and then Pond Bay.

As we successfully navigated into Pond Bay, relying principally on the boat's Garmin Chartplotter and two very astute bow observers, I watched the iPad and noted that the pre-loaded route was 250'-300' north of our actual and correct path. I should have checked the app again later in the trip, but was so disillusioned by the first experience that I just put it back in the bag. Will try again in the Spanish Virgins in October, but will not rely on it.