Humminbird XTM 9 28 T Single/Dual Beam Trolling Motor Transducer
I was skeptical at first about a trolling motor mounted transducer, but I had no choice as my mini bass boat is made of plastic and there was no where else to mount it, unless I manufactured a bracket to put it on.  But I have to say after using it for all of spring and most of the summer, it has proven to be very accurate and reliable.  I highly recommend this transducer if you are in need of a trolling motor transducer for a Humminbird depth finder.