Rocas Soledad Missing on Garmin Blue Chart of Mexico

[nhschneider]

As we journey south from San Diego, we're having fun using our new Garmin 6208 Chartplotter. However, as we sailed south of Punta Santo Tomas, we noticed that the Rocas Soledad, located at 31 degrees 33.1 minutes north, 116 degrees 43.3 minutes west do not show up on the Garmin BlueChart. We tried all scale levels and they just aren't shown. These rocks are always above the surface and are about 1.5 miles off shore. The passage between the shore and the rocks is clear. Our other chartplotter uses CMap and it does show Rocas Soledad.

Have others found blatant omissions on electronic charts? I'm certain that Garmin has somewhere in their fine print that they're freed from any liability but these rocks are only about 80 miles south of San Diego. We transitted them in the day but if someone were making the passage at night it could be a problem without radar.

It's kind of shaken my confidence in electronic charts. Does anyone else feel this way?

Fair winds and calm seas.

[neophytecruiser]

nhschneider,

We have a Garmin 76-CSx hand held Chartplotter with Blue Chart v8.0 installed. Our chart clearly shows an uncovered rock at 31 33.16 N and 116 43.52 W, bearing 257 degrees magnetic and ~1.7 nm off the south point of Puerto Santo Tomas. Apparently, this datum was transferred from Chart Us21140. You didn't indicate which BlueChart version was loaded in your Garmin and whether you had recently checked for updates. It's interesting that this rock isn't showing on your Chartplotter and, as you pointed out, could be a serious omission when navigating close to shore at night.

It's been our experience that electronic charts shouldn't be relied upon as the sole source for navigation decisions. It pays to confirm positions and hazards to navigation on paper charts, as well as relying on your own senses to determine the accuracy of your whereabouts. Certainly further south in Mexico, our electronic chartplotter showed us clearly ashore when approaching PV when we were still 1-2nm from the beach. Hopefully, with the new charting of Mexican waters by the Mexican Navy, some of these anomalies will disappear as more accurate surveys are incorporated into the existing digital chartplotters. However, the age old admonishment of not relying on single source data for good dead reckoning is still good advice.

We have always been taught that navigation is the result of civilization, but modern archeology has demonstrated very clearly that this is not so. - Thor Heyerdahl

[delmarrey]

And if you do find an error, you can report it to Blue Chart. Go to their web site.

[s/v Moondancer]

We are in Mexico on the Atlantic side and our Navionics chart shows almost no detail of the coast between Belize and Cozumel but then becomes reasonably accurate north of there. It all depends on what paper chart the data is taken from.

We never attempt night entries based on data from the chart plotter as the data cannot be relied upon once you leave the US. Last week we spent 8 hours hove-to, in deep water, off Cancun waiting for daylight to enter Isla Mujeres and that is one of the best lit entries in Mexico.