Bob,  Over a period of time, I have utilized several types of depth
finder equipments: lead lines; and echo sounders that indicate the
distance to the bottom with graphic displays, scribe marks on paper,
echo return heard via earphones, dial indicators (pointers), and
flasher-type indicators. On sailboats, some of us have to watch our
pocketbooks...so...we try to obtain reliable equipment that is easy to
operate and interpret...and does not cost a fortune.
     The least expensive, most accurate, and most reliable type of
sounding equipment is the lead line...which you can make yourself.
However, you must be moving slowly in relatively shallow water to
utilize it and get accurate readings. The lead line (hand lead) is
particularly useful if you go aground and need to find the way back to
the deep water. It is also useful to sound a slip you are in, or are
contemplating renting, to see if the depth of water is sufficient to
keep you from "touching bottom" throughout the range of the tide.
     I selected a simple pointer-type indicator sweeping over a
100-foot scale, mounted on the forward bulkhead of the cockpit, with
the transducer mounted through the hull, for my first sailboat
installation (on a Seafarer 26). It worked as advertised...and never
failed. But, in several years time, the sun faded the instrument
numbers, graduations, and dial color, and warped the needle until it
touched the glass face of the instrument...even though I covered the
face of the instrument when it was not in use. I also found the needle
to be too "jumpy" in shallow water with an uneven bottom...like when
transiting over a rocky bottom. Even with the gain way down, the
needle fluctuated way too much, on occasion, to present reliable depth
information. And, it "scared" one when it carried on like that.
     When I purchased my second sailboat...a Cape Dory 36...I bought a
very basic echo sounder...a Pearce-Simpson Dolphin 101...which is a
compact, solid state, flasher type indicating instrument that
indicates water depth, in one foot increments, to 100 feet. The
transducer is mounted through the hull, amidships, to starboard of the
keel. The indicator is mounted below, from the overhead, over the
chart table...which is just inside the companionway hatch and ladder -
to starboard. This has proven to be a good choice and setup for the
past 16 years I've utilized it...and...it has never failed.
     I like the flasher presentation best because you can see the
outgoing pulse of energy, and the returning echo, on the indicator
ring. This shows any misalignment you may have on the indicator...and
compensations can be made to obtain the correct sounding. You can also
see what effect the various gain settings are doing to your
signal...and can adjust that setting accordingly. With a flasher, you
can pick out the true sounding if the bottom is "bad" (sending back
many echoes and reverberations) by intelligently "inspecting" the
returned signal. And, many times, you can tell what type of bottom is
down there by the appearance of the returned pulse.
     The inside location of the instrument has proven to be the right
spot (for me). First off: it's out of the weather. Second: it's
visible from both the cockpit and the navigation station. An echo
sounder is a valuable piece of navigation equipment as well as an
instrument to keep you from going aground...especially along many
areas of the east coast of the U.S. where one can stay the desired
distance off-shore by "riding" fathom curves. Third: when the weather
is bad, and one is approaching a shallow anchorage or harbor, it's
nice to be able to put your "mate" down below on the echo sounder and
have him or her call out any change in the soundings, while you, at
the wheel, maneuver accordingly. Sometimes, soundings alone, during
the final approach, indicate where to anchor...and when.
     I'm a "KISS" man..."Keep it simple, stupid." This is one example
along that line of thinking.             --- Bob ---
--- WILDMAIL!/WC v4.12 
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