🚀 go-pugleaf

  I am interested in buying a depth finder and I have gathered a lot of
literature from various manufacturers (Humminbird, Apelco, Eagle, Raytheon,
King, Lowrance, etc.) and I would like to use this for an unintended
purpose, specifically, rock-finding.  I have narrowed the choice of
instrument down to a motorized flasher instead of a chart recorder or an LCD
graphic display or a digital (numeric) depth indicator.  What I want to do
is aim the transducer forward instead of downward.  I understand in order to
do this it must clear the bottom of the transom.  I probably will not be
able to go any faster than trolling speed (if that) due to cavitation on the
face of the transducer and also to keep stresses off of its mounting.  I
would want to lower this transducer into the water below the boat when
running at this low speed on a periscope type arrangement.  The cone-shaped
beam of the transducer would be looking ahead of the boat and the first thing it would hit is the surface of the water or the bottom, depending how it is aimed.  This would be indicated as a constant depth band on the flasher.  Any decrease of this depth value would indicate the approach of an object.  I under-
stand that flashers use a frequency of 200 kHz and have beam angles that vary
from 8 degrees to twenty degrees depending on manufacturer.  Chart recorders
operate at 50 kHz (the big ones anyway) and have beam angles down to 4 degrees
.  Can I use a different transducer from one manufacturer on a different 
flasher to get the beam angle I want? (as long as I get one that operated in
on the same frequency?)  Will this scheme work or am I totally out of my tree?
I want to buy a flasher and just play with the transducer while swimming 
around (when it gets warmer) and noting the effect on the display.  Should I
bother or am I wasting time and money? Thanks in advance to anyone who has had
experience with these devices.  Bob Lagasse