On 2007-06-26 19:39:48 -0400, Lew Hodgett said:

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

Obviously, you don't sail the Chesapeake. We spend most of our time in
less than 20 feet; sometimes our speed reads greater than the depth. We
often raft up with others, so knowing the actual depth is even handier.

We originally calibrated by anchoring where we had a fairly flat
bottom, measured the depth, then adjusted the gauge to match. If it
reads 4.3, we're floating; 4.2 means we just bumped.

--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
Xan's new pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI pages: http://homepage.mac.com/jerelull/BVI/