What I can't figure out is why I haven't seen a CD software of the Defense
Department's underwater mapping system, making your $700 depth finder
unnecessary. The DoD has mapping data of ever underwater place on the
planet. This should be coupled with your favorite nav software so instead
of the stupid old chart's little depth numbers, you'd get an underwater
surface contour map in any direction around your boat's GPS
position....like the street maps ashore. Every known underwater
obstruction would be there that they know of.

Your measured depth would be correlated with the data's stored depth and
the entire output 3-D display would be continuously depth-corrected,
compensating for tides, etc.

Here we sit still looking at a paper chart on a huge computer....stupid.



"Aaron" wrote in
oups.com:

A fishfinder can also be significant help in discerning bottom features
and types when anchoring. I've also been looking into the forward
looking sonars from Interphase and Echopilot, which can actually show a
bit of what's in front of your boat, not just what's straight down. The
Echopilot bronze is around $700 on Sailnet, and is similar-sized to a
regular depth finder.

Aaron Tinling
s/v Sweet Destiny
www.navagear.com