I have the Lowrance LCX-27C, and it is set up perfect for me , but being that I fish the muddy Mississippi River most of the time, my settings might not be close to what will work for you.
Sensitivity: I usually run it around 68%. I will usually back it off in clearer water.
Chart Speed: I will set on MAX for faster returns
Ping Speed: Set to MAX also.
Colorline: I use the default setting.
With these setting I am also getting high speed readings of up to 47 MPH.I I also have my transducer dropped just a hair below my transom. This is giving me almost perfect arches. Good Luck!:big_smile: