Sailing from Nuevo Vallarta (MX) northbound to Punta Mita (Banderas Bay), was an excellent example. My boat is the red/green triangle that points north and appears to be on the beach (shoreline). (Disregard the orange arrow that is telling me which way to turn.) Also, note that there is another boat (solid red triangle) that is apparently about .25 nm inland from the shore.
Don’t cue the ominous music and fear for “our hero!” In actuality, I’m about .75 nm offshore and the other boat is anchored near the shore. It was a beautifully warm and clear day, so a visual check of my position proved the chart-plotter had seemingly lost its mind.
The real culprit and reason for the error was a software programming glitch inherent to the chart files downloaded from the “latest” update by Garmin. This underscores the need to invoke “The Navigator’s Rule.” If the visibility was poor or it was nighttime, using the radar (another aid to navigation) would have been a valid crosscheck.
By the way, during the entire nine-month cruise from California to Mexico and return, this was the only time the chart-plotter was in error. Always maintain position awareness, and follow the “rule!”
Submitted by: Neal Doten s/v No Moss