It really comes down to the newer the system the better the electronics. The
ST290 transducers are equipped with intelligent transducer pods that share
information. The ST60's transducer are combined with better electronics in
the displays for better accuracy. While the ST40's are more or less the
entry level with less electronics and accuracy. Being geared towards the
Powerboat community. The shorter design of the ST40's makes for easier
installation in different powerboat hull designs. If your a sailor and want
good reliable entry level instruments go with the ST60.

Jack
"Ryk" wrote in message
...

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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