Here's Dougs recommended starting settings ...
I might add that it is very important to frequently adjust the SI Sensitivity setting ... Bottom composition, water depth, and water clarity have a huge impact on how bright and dark the SI image will display due to the intensity of the return sound pulse ...
*Press Menu 1 time while viewing SI ...
*Cursor down to "SI Enhance" ...
*Cursor right to overlay the "SI Enhance" menu over the SI image ...
Use the "SI Sensitivity" setting as a brightness control for the Enviromental conditions that are constantly affecting the SI image ...
Rickie