Hi Ryk,
You may want to consider putting your transducer inside the boat. If
you choose a place where the hull is not too thick, you will not get
appreciable attenuation of the signal. I have had this arrangement on
my
sailboat for many years and get readings over 200 feet with my old
Heathkit Depthsounder. You have to get a good seal between the
transducer
and the hull. Originally, I had constructed a box to house the
transducer, which was filled with fluid. I later found that this
arrangement worked without the fluid. You might check the various
sailing
magazines for articles on this. My sources are several years old.

Sherwin Dubren

Ryk wrote:


I have two questions I haven't got good answers to, one about the
transducers themselves and another about the mounting.

The Raymarine catalogue shows transducer dimensional drawings. The
drawings for the ST 290 and ST 60 transducers are identical while the
ST 40 transducers are the same diameter but shorter. They brag about
the advanced transducers on the 290, but say nothing special about the
60s or the 40s. Does anybody know the differences in the transducers?

I currently have plastic fittings in the hull for SR Mariner
instruments which fit into 2 1/8 holes. The Raymarine fittings go into
2 inch holes. What's the best approach to creating a sound mounting
for the through hulls?

Ryk, just about ready to wrap up the season
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