kitjv
Junior Nomad
Posts: 98
Registered: 12-13-2006
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Navigational Charts
What is the best source for detailed navigational charts for inshore water in the Sea of Cortez? My interest is more for fishing than for navigation
per se.
Thank you!
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Hook
Elite Nomad
Posts: 9009
Registered: 3-13-2004
Location: Sonora
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Mood: Inquisitive
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Some like the Baja Directions maps (I think that's the name). I prefer the Fish-N-Map ones.
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BajaBruno
Super Nomad
Posts: 1035
Registered: 9-6-2006
Location: Back in CA
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Unless things have changed since I was buying Mexico charts to navigate with (very possible), the Mexico charts are largely based on old sailing ship
surveys throwing lead lines. It is almost amusing to look at a chart and see the depths spaced at regular intervals where they took their marks, and
then the boat tacks and you see a line of depths maybe 100 degrees off the last line. Those charts are pretty useless for fishing.
What I'd like to know is if the newer GPS chartplotters will "learn" the water they are used in--I mean update their own data with real-world readings
as you are traveling through the water. I thought I heard that they would, but I haven't been able to find anything on that concept lately.
Imagine hundreds of chartplotters storing data everytime somebody turned them on--heck, we'd have great, real-world charts of most of the coast in
just a couple of years.
Christopher Bruno, Elk Grove, CA.
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cbuzzetti
Nomad
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Registered: 5-22-2006
Location: Atascadero, Ca
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Yes I also would love some detailed charts for Gonzaga area.
I have used my GPS Chart plotter with Navionics Gold Chip in the San Felipe area and have noticed some huge discrepencies from what is on my screen to
what is real.
The biggest factor was that the SF harbor is located many miles South as compared to my chart plotter. The shore line was mostly correct. I traveled
as far south as Percebu on the water and came across sand bars that were 1-2 miles off shore. This is an area that must be approached with caution.
I would gladly pay for a learning chart plotter.
BajaBuzz
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Alan
Super Nomad
Posts: 1626
Registered: 4-6-2005
Location: Yucaipa, CA/La Paz
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I don't believe I have ever heard of a "learning" chartplotter. The best I can do on mine (Garmin 182C) is plot the hazards as I find them as
waypoints.
I must agree the charts in the chips are not always real good down in Baja. Last time in BoLA it showed me trolling across several islands.
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Hook
Elite Nomad
Posts: 9009
Registered: 3-13-2004
Location: Sonora
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Furuno has made GPS units in the past that can "learn" discrepancies in charts, to a point. My older 1650 has an offset correction. You engage the
offset when you are at a known location and a crosshair appears. You then move the crosshair to the same point on the chart and depress a button to
lock in the offset. It shifts the entire map based on the difference. However it removes the offset when you power down and there can still be some
discrepancies resulting from an incorrect drawing of the coastline, rocks, islas, etc. It worked pretty good in the Mulege area for me.
Dont know about their newer ones or other mfgrs.
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BajaBruno
Super Nomad
Posts: 1035
Registered: 9-6-2006
Location: Back in CA
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I've had the same experience as Alan and Cbuzzetti---the charts are based on old sextant fixes and they don't overlap well to the far more exact GPS
fixes.
Near Cabo SL I took my GPS coordinates and recorded a fix on the chart which put me about 100 yards onto the beach, yet the boat was floating
well offshore! The chart was shifted about one nautical mile to the west at that location and included a notice saying that was so, but the mapmakers
had no way of making the correction without squeezing or expanding area.
With all the boats plying these waters it seems a pity that everyone can't record data and submt it to somewhere so the charts can be updated.
Christopher Bruno, Elk Grove, CA.
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