On Feb 23, 7:55�am, "mark" wrote:
I am going to buy a sounder for use in my aquaculture operation. I
need it to be as accurate as possible in determining if my mussel
socks are touching the bottom or are 1' off the bottom. The water is
only 20 feet deep and it is a mud bottom. *Some people are using SiTex
106-L which has 300 watts of power and 50 or 200KHz and some are using
Furuno FCV 620 which has 600 watts of power and I saw one with a
Hondex. For my application is there any advantage of one over the
other? Also My boat is aluminum and some dealers are telling me to use
a bronze transducer but make sure it is isolated with plastic bushing
and other are saying use a special ordered aluminum transducer. And
finally would it be most accurate if it pointed straight down or would
having it 10 degrees off to one side (flat against the hull) make a
big difference, if so could I fabricate a level flat spot on the hull
to mount it to but would this create to much turbulence for it to read
properly? I want it as far forward as possible not on the stern. Thanks

You can probably get by with 300 watts if you only want to take
soundings in 20-feet and less. Since an accurate reading is pretty
critical to you in your quest to locate a spot exactly 1-foot off the
bottom, try to put the transducer in as vertically as possible. Most
boats don't have a truly flat spot that is parallel to the bottom, so
a "fairing block" can be used to square up and support the transducer.
Many boaters use a transom mounted transducer that will solve a lot of
the alignment concerns. Either the bronze transducer with the plastic
bushing or the aluminum tranducer should work- but I would lean toward
the aluminum transducer. The plastic bushing will keep a bronze
transducer from contacting the aluminum and aggressively corroding it,
but there will still be electrolysis concerns when the bronze and the
aluminum and both submerged. One of the drawbacks of metal hulls is
the need to be super vigilant for electrolysis.