Look at the dates on the chart shown above. 1873 to 1901? The First Mate thinks this chart belongs a museum rather than in current use on an ocean-going boat!
Granted that, unless subject to seismic activity, not much changes underwater in 100 years, there remains a lot of data (like rocks that have been found or could be found with modern equipment) that ought to grace charts used by mariners today. Modern mariners would greatly appreciate such information, but that apparently does not concern the Mexican government.
An interesting phenomenon occurs when one needs to find one of the new marinas that have been built in the last 100 years. Many have been placed in dredged-out estuaries or even dug out of the land. These marinas naturally do not show up on our 100-year old charts, and no attempt has been made yet to locate them for the searching mariner. We have been in two already which are not on our charts: Mazatlan and Paradise Village Marina. To find these marinas, we have to rely on our guidebooks and the GPS waypoints they list and not our charts.
The First Mate must give the Mexican government some credit. In a few cases, where navigation need would appear to be most urgent, updates and additions to the charts have been made. For instance, the navigation chart to the main harbor in Puerto Vallarta was added and updated. We motor in there for fuel prior to heading south to Manzanillo. Cruise ships use this harbor. It is tight once one is beyond the entrance, and it is reassuring to have a fairly accurate chart of where to go to find the fuel dock. Chart we may have, but we still carefully monitor our depth meter and hope that channels have been recently dredged by harbor maintenance to their charted depths.
A further interesting discrepancy occurs between our charts and our actual location determined by GPS coordinates. Our actual GPS position is displayed on the charts on our computer and on our Furuno chart plotter, but there is a big difference between where we actually are and where we are shown on these charts. At the end of each day as we head shoreward to anchor and to go into harbor, we often end up “aground”. Night after night, Avante shows herself to be an agile and adventurous amphibian as we see ourselves located well inland according to the charts. The First Mate feels like Avante is turning into the search for Noah’s Ark. Which mountain are we going to alight on tonight?
The chart shown above is what shows up on our computer. The 3 shades of Blue are water. Gold is land. The Red line is Avante’s track. The Yellow dot near the town of “Ipala” is Avante anchored well up in the surrounding hills. Look at the light blue area. The circles are rocks thru which we supposedly motored.
The reason for this goes back to the inaccurate Mexican charts. In Banderas Bay anchored in Punta Mita the charts are about 1 1/2 miles off from our actual GPS location. The Captain decides one evening that he is going to tackle this discrepancy and try to align chart and GPS. It takes a lot of figuring and finagling of buttons and controls, but he finally does it. The adjusted chart now shows us anchored where we actually are. This is a relief! The next morning we take off. Things look good until we get about 20 miles down the road and find that the actual location of nearby land is not where it shows on Bill’s meticulously adjusted charts. We conclude that the problem is that the charts are blissfully and consistently inaccurate! The only thing reliably consistent about these Mexican charts is their constant inconsistency. To deal with this, The Captain would have to reconfigure the data every time we change our location, and that is just too time-consuming and frustrating. We are just going to have to put up with this misguided visual image and do our own mental math to locate Avante on the charts.
For the last three years, we have been sailing with US and Canadian charts in some very remote areas with tricky navigation issues. US charts are very good, and Canadian charts are superlative. All have been updated using modern tools like GPS and satellite photos to accurately determine the position of things. If a series of rocks and shoals were ahead of us, our GPS location was right on, and we could confidently steer thru and around them. If a depth was listed, we knew we could count on it to be accurate. Not so here in Mexico. How we miss those so very accurate charts!
Fortunately, cruising Mexico does not hold the navigation challenges that one encounters in the Pacific Northwest. To be on the safe side, The Captain keeps Avante at least 2 miles off shore and more often closer to five. When our books talk about a rock 1 1/2 mile off shore or they say to give a point a wide clearance, we on Avante double the distance and steer clear. Avante may show up aground on Mexican charts. We can live with that - just as long as we do not end up aground in Mexican waters!
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