On Jun 26, 7:39 pm, Lew Hodgett wrote:
wrote:

I agreed with the fact that what counts is how much water is under
the keel
However, I have been, for years, using the depth to validate my
position on
the chart.
Conversely, with today's electronics I could say 100 feet + 6
(draft) should
read 106 feet on the chart.
This way I could validate my position with the radar and GPS.

Trying to use chart data, some of it at least 100 years old, to
validate depth, to validate position?

You have got to be kidding.

If you find yourself in less than 20 ft of water, time for a lead
line, IMHO.

At that point, screw the instruments.

Lew

I agree with Lew, their's also tides and water level varriation due to
wind to contend with, not to mention if they have dredged since your
chart was updated. Using depth to tell where you are is really only
useful if your running out of water. If your chartplotter says their
should be 10 feet of water, and your depth sounder says their's only
2, you've got a problem. If you'r coming in from way offshore, depth
can tell you when you'r getting close to the beach, but that's it,
nothing more.

John