Cabledawg, check aroudn the forum by searching (tab at the top right) and look at a number of postings on just what you are talking about. Transducver is sensitive to boat type, jull type, speed of usage, motor location.
Rather than make a long lengthy reply I think you will find what you want in the search.
This forum has volumes of information on file.
If you dont find it, then we can help some more.
Chuck
