Salomon Fringe wrote in news:484cdba2$0$6032$ba620dc5
@text.nova.planet.nl:

(I need zero depth performance
for inland waterways). Does anybody know of a unit/brand/type that
would
work for me? I'm not interested in fish, just displaying depth.


You're asking for the impossible. The depth limit is determined by the
speed of sound and the pulse WIDTH (time) of the ping. A zero depth
would require a zero ping, which doesn't transmit anything. The other
problem is once the ping transmitter is shut off on a ping, it takes a
tiny amount of time for the receiver to come back on to listen for the
return from the ping, some latency is inevitable.

So, you want the shortest ping time unit with the fastest response you
can get to that ping.....and they're all about the same, mostly useless
under 2 ft. of depth, right where everyone needs it.

What I always thought we needed was a sort of underwater "curb feeler"
like we used to put on the pimpmobiles. A couple of stiff wires that
would protrude down into the water 3 ft from the BOW that would make an
awful griding noise like the curb feelers did through the hull alerting
us the expensive lower unit was about to be torn off by the bottom
rocks...while we're feeling our way along through the shallows....we
shouldn't be in in the first place.

The feelers would be spring loaded and fly back along the hull at speeds
above no wake speeds.

Just for reference, I find the depth sensed by the simplest of depth
meters so close to the bottom is much better than the "fish finders" with
their charting displays. But, the charting display gives you some
instant idea of whether we're getting shallower or deeper and how fast so
you can turn away or back....