Originally Posted by TQA
Errr if you are planning to navigate using some kind of onscreen electronic chart and rely on the depths displayed there here is a note of caution heard from the owner of a boat in a boatyard waiting for the damage surveyor to arrive.
"Well the chart plotter showed us in 42 feet of water when we went aground on the reef. "
Rely on a working depth sounder and set the alarm!
I keep returning to this and scratching my head. Perhaps you can help me understand the problem with the charter plotter? The NOAA RNC charts that I use mirror the paper charts. So if the paper chart says one depth, the e chart should say the same. Since the RNC charts are updated much more often (sometimes weekly), I update my paper charts using the weekly Local Notice to Mariners.
So I wonder if the owner in your example misread the chart plotter? Or, are the charts used in chart plotters different? I don't use one, I use paper and a laptop, so I'm just curious.