On Jun 9, 8:06*pm, "Eisboch" wrote:
"Short Wave Sportfishing" wrote in messagenews:f8fr44dh4d6e09iqlo00m3n5gf8993hnkq@4ax .com...

On Mon, 09 Jun 2008 11:04:13 -0400, wrote:

In a sailboat, the transducer would be mounted in the hull, above the
level of the top of the keel, so you would have 4-10 feet (depending
on how deep a keel you have) of water even with the keel scraping
bottom. Sounders usually have a "keel offset" setting to compensate
and tell you how much depth remains after the keel height is
subtracted.

I understand that - I'm not clear on the whole zero depth concept.

The Navigator had a Raytheon system on it that was calibrated for the
transducer location versus the actual hull depth.
It was accurate to 2.8 feet. * Ask me why I know.

Eisboch

The simple guess would be that your boat needed 2.9? Good to see
you stop back in.. We have all been working very hard to keep it nice
while you were away...