I am considering getting a fishfinder for depth sounding. I know all of the techniques for mounting a transducer in the hull. I am intrigued by the units that have speed and temp functions, the Navman unit in particular. They utilize transom mounts. Navman says that thier transom mount units are not recommemded for displacement hulls. I am looking for ideas from people who have usd any units like this, and the mounting options available. I don't plan on getting a GPS n the near future because I sail on a lake where this is really unecessary but a knotmeter etc. would be just neato. Thanks for the info. Steve